TAKASU Fugo

researchmap

Profile and Settings

• Name (Japanese)

  TAKASU

• Name (Kana)

  Fugo

Degree

• Doctor of Science, Kyoto University

Research Interests

• Mathematical and computational study on population and evolutionary dynamics (Mathematical modeling).\nPoint pattern dynamics, evolutionary games, stochastic population dynamics applied to biological conservation.

Research Areas

• Life sciences, Biophysics

Research Experience

• Jan. 2007, Professor
• Nov. 2000, Dec. 2006, Associate Professor
• Jan. 1997, Nov. 2000, Lecturer
• Sep. 1994, Dec. 1996, Research Assistant
• Apr. 1994, Aug. 1994, JSPS Research Fellow

Education

• Apr. 1990, Aug. 1994, Kyoto University, Graduate School, Division of Natural Science, 生物物理学
• Mar. 1990, Kyoto University, Faculty of Science, Department of Biophysics

Teaching Experience

• Science Open Laboratory II E, Nara Women's University
• Science Open Laboratory I E, Nara Women's University
• Academic Guidance Understand Biology using Matheamtics, Nara Women's University
• Passage 24A, Nara Women's University
• Population dynamics, Nara Women's University

Association Memberships

• Ecological Society of Japan
• Japan Society of Mathematical Biology
• Ornithological Society of Japan

Ⅱ．研究活動実績

Published Papers

• Refereed, 2023, 10.1016/j.jtbi.2023.111579
• Refereed, 22 May 2022, 13, 10.3389/fpls.2022.886867
• Refereed, Applied Mathematical Modelling, Elsevier BV, Asymptotic behaviors of stochastic epidemic models with jump-diffusion, Nguyen Thanh Dieu; Takasu Fugo; Nguyen Huu Du, Oct. 2020, 86, 259, 270, Scientific journal, 10.1016/j.apm.2020.05.003

  DOI URL
• Refereed, Journal of Sichuan University (Engineering Science Edition), Rumination Behavior Difference During Rutting Season Between Cervus nippon nippon in Japan and Elaphurus davidianus in Dafeng, Zhang Yigui; Ullah Sana; TAKASU Fugo; Li Zhongqiu, Jan. 2020, 39, 50, 55
• Refereed, 日本森林学会誌101巻1号30-34, マツ枯れ進展における潜在感染木の役割に関する数理的研究, TAKASU Fugo, Jan. 2019, 101, 1, 30-34, 10.4005/jjfs.101.30

  DOI URL
• Refereed, Journal of Theoretical Biology, Equilibrium properties of the spatial SIS model as a point pattern dynamics - How is infection distributed over space?, TAKASU Fugo, 2019, 468, 12-26, 10.1016/j.jtbi.2019.02.005

  DOI URL
• Refereed, ECOLOGY AND EVOLUTION, WILEY, How can distinct egg polymorphism be maintained in the rufescent prinia (Prinia rufescens)-plaintive cuckoo (Cacomantis merulinus) interaction-a modeling approach, Wei Liang; Canchao Yang; Fugo Takasu, In avian brood parasitism, both the host and the parasite are expected to develop various conflicting adaptations; hosts develop a defense against parasitism, such as an ability to recognize and reject parasitic eggs that look unlike their own, while parasites evolve egg mimicry to counter this host defense. Hosts may further evolve to generate various egg phenotypes that are not mimicked by parasites. Difference in egg phenotype critically affects the successful reproduction of hosts and parasites. Recent studies have shown that clear polymorphism in egg phenotype is observed in several host-parasite interactions, which suggests that egg polymorphism may be a more universal phenomenon than previously thought. We examined the mechanism for maintaining egg polymorphism in the rufescent prinia (Prinia rufescens) that is parasitized by the plaintive cuckoo (Cacomantis merulinus) from a theoretical viewpoint based on a mathematical model. The prinia has four distinct egg phenotypes: immaculate white, immaculate blue, white with spots, and blue with spots. Only two egg phenotypes, white with spots and blue with spots, are found in the cuckoo population. We show that the observed prinia and cuckoo phenotypes cannot be at an equilibrium and that egg polymorphism can be maintained either at stationary equilibrium or with dynamic, frequency oscillations, depending on the mutation rates of the background color and spottiness. Long-term monitoring of the prinia-cuckoo interaction over a wide geographic range is needed to test the results of the model analyses., Aug. 2017, 7, 15, 5613, 5620, Scientific journal, 10.1002/ece3.3090

  DOI URL
• Refereed, ECOLOGICAL MODELLING, ELSEVIER SCIENCE BV, Spatially explicit model applied to pine wilt disease dispersal based on host plant infestation, Tuyen Van Nguyen; Young-Seuk Park; Chang-Sik Jeoung; Won-Il Choi; Yong-Kuk Kim; Il-Hyo Jung; Nanako Shigesada; Kohkichi Kawasaki; Fugo Takasu; Tae-Soo Chon, Pine wilt disease is a serious pest for pine trees in many countries, especially in Asia (e.g., South Korea, Japan, China and Taiwan). In this study, we characterised dispersal patterns (e.g., direction and area) of pine wilt disease in the southern part of Korea in four-year period based on the cross-correlation function. The most likely distance of the highest infestation probability after one year is around 1.2 km from the disease source according to the distribution of pairwise distance. Subsequently, a spatially explicit model was developed in two dimensions by incorporating biological and environmental events, including influence of infested neighbourhoods, short- and long-distance dispersal, asymptomatic carriers and typhoon. The model results were in good agreement with field data when evaluated using the receiver operating characteristics and pair-correlation functions. Asymptomatic carrier played an important role in the spread of PWD. The infestation probabilities based on the spatially explicit model provided the map of spatial conformations that would be effective in addressing disease occurrence in both local and global aspects. (C) 2016 Elsevier B.V. All rights reserved., Jun. 2017, 353, 54, 62, Scientific journal, 10.1016/j.ecolmodel.2016.10.022

  DOI URL
• Refereed, BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, WILEY-BLACKWELL, Disappearance of eggs from nonparasitized nests of brood parasite hosts: the evolutionary equilibrium hypothesis revisited, Bard G. Stokke; Eivin Roskaft; Arne Moksnes; Anders Pape Moller; Anton Antonov; Frode Fossoy; Wei Liang; German Lopez-Iborra; Csaba Moskat; Jacqui A. Shykoff; Manuel Soler; Johan R. Vikan; Canchao Yang; Fugo Takasu, The evolutionary equilibrium hypothesis was proposed to explain variation in egg rejection rates among individual hosts (intra- and interspecific) of avian brood parasites. Hosts may sometimes mistakenly reject own eggs when they are not parasitized (i.e. make recognition errors). Such errors would incur fitness costs and could counter the evolution of host defences driven by costs of parasitism (i.e. creating equilibrium between acceptors and rejecters within particular host populations). In the present study, we report the disappearance of host eggs from nonparasitized nests in populations of seven actual and potential hosts of the common cuckoo Cuculus canorus. Based on these data, we calculate the magnitude of the balancing parasitism rate provided that all eggs lost are a result of recognition errors. Importantly, because eggs are known to disappear from nests for reasons other than erroneous host rejection, our data represent the maximum estimates of such costs. Nonetheless, the disappearance of eggs was a rare event and therefore incurred low costs compared to the high costs of parasitism. Hence, costs as aresult of recognition errors are probably of minor importance with respect to opposing selective pressure for theevolution of egg rejection in these hosts. We cannot exclude the possibility that low or intermediate egg rejection rates in some host populations may be caused by spatiotemporal variation in the occurrence of parasitism and gene flow, creating a variable influence of opposing costs as a result of recognition errors and the costs of parasitism., Jun. 2016, 118, 2, 215, 225, Scientific journal, 10.1111/bij.12733

  DOI URL
• Refereed, JOURNAL OF ETHOLOGY, SPRINGER JAPAN KK, Modeling the cuckoo's brood parasitic behavior in the presence of egg polymorphism, Wei Liang; Canchao Yang; Fugo Takasu, The common cuckoo Cuculus canorus is a brood parasite that utilizes many host species. These have evolved defense against parasitism to reject cuckoo eggs that look unlike their own and some cuckoos have evolved egg mimicry to counter this defense. Egg phenotype indeed plays a key role for both the cuckoo and its hosts to successfully reproduce. It has been argued that cuckoos should parasitize host nests where egg phenotype matches because this makes parasitism more successful. Details of the cuckoo's parasitic behavior, however, largely remains unknown if they really parasitize hosts depending on "egg matching". In this paper, we model a time sequence of parasitic events in which a cuckoo finds host nests and decides to parasitize them or not in the presence of egg polymorphism. We evaluate which strategy is optimal: (1) opportunistic parasitism where cuckoos parasitize hosts irrespective of the phenotype, or (2) non-opportunistic parasitism where cuckoos parasitize hosts where egg phenotype matches. The analysis showed that either of the two strategies can be optimal. Factors not considered in the model, e.g., ecological and evolutionary changes both in the cuckoo and the host side, are discussed to explain apparent contrasts observed in some cuckoo-host interactions., May 2016, 34, 2, 127, 132, Scientific journal, 10.1007/s10164-015-0455-3

  DOI URL
• Refereed, NATURE COMMUNICATIONS, NATURE PUBLISHING GROUP, Ancient origin and maternal inheritance of blue cuckoo eggs, Frode Fossoy; Michael D. Sorenson; Wei Liang; Torbjorn Ekrem; Arne Moksnes; Anders P. Moller; Jarkko Rutila; Eivin Roskaft; Fugo Takasu; Canchao Yang; Bard G. Stokke, Maternal inheritance via the female-specific W chromosome was long ago proposed as a potential solution to the evolutionary enigma of co-existing host-specific races (or 'gentes') in avian brood parasites. Here we report the first unambiguous evidence for maternal inheritance of egg colouration in the brood-parasitic common cuckoo Cuculus canorus. Females laying blue eggs belong to an ancient (similar to 2.6 Myr) maternal lineage, as evidenced by both mitochondrial and W-linked DNA, but are indistinguishable at nuclear DNA from other common cuckoos. Hence, cuckoo host races with blue eggs are distinguished only by maternally inherited components of the genome, which maintain host-specific adaptation despite interbreeding among males and females reared by different hosts. A mitochondrial phylogeny suggests that blue eggs originated in Asia and then expanded westwards as female cuckoos laying blue eggs interbred with the existing European population, introducing an adaptive trait that expanded the range of potential hosts., Jan. 2016, 7, 10272, Scientific journal, 10.1038/ncomms10272

  DOI URL
• Refereed, JOURNAL OF THEORETICAL BIOLOGY, ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, Beyond pairs: Definition and interpretation of third-order structure in spatial point patterns, Chiho Kaito; Ulf Dieckmann; Akira Sasaki; Fugo Takasu, Spatial distributions of biological species are an important source of information for understanding local interactions at the scale of individuals. Technological advances have made it easier to measure these distributions as spatial point patterns, specifying the locations of individuals. Extensive attention has been devoted to analyzing the second-order structure of such point patterns by focusing on pairs of individuals, and it is well known that the local crowdedness of individuals can thus be quantified. Statistical measures such as a point pattern's pair correlation function or Ripley's K function show whether a given point pattern is clustered (excess of short-distance pairs) or overdispersed (shortage of short-distance pairs). These notions are naturally defined in comparison with control patterns exhibiting complete spatial randomness, i.e., an absence of any spatial structure. However, there is no rational reason why the analysis of point patterns should stop at the second order. In this paper, we focus on triplets of individuals in an attempt to quantify and interpret the third-order structure of a point pattern. We demonstrate that point patterns with "bandedness", in which individuals are primarily distributed within bands, can be detected by an excess of thinner triplets at a characteristic spatial scale linked to the band's width. In this context, we show how the generation of control patterns as a reference for gauging a test pattern's triplet frequencies is critical for defining and interpreting the third-order structure of point patterns. Since perfect information on a point pattern's second-order structure typically suffices for its unique reconstruction (up to translation, rotation, and reflection), we conjecture that it is essential to minimally coarse-grain such second-order information before using it to generate control patterns for identifying a point pattern's third-order structure. We recommend the further exploration of this conjecture for future studies. (C) 2015 Elsevier Ltd. All rights reserved., May 2015, 372, 22, 38, Scientific journal, 10.1016/j.jtbi.2015.02.004

  DOI URL
• Refereed, AVIAN RESEARCH, BIOMED CENTRAL LTD, Why cuckoos should parasitize parrotbills by laying eggs randomly rather than laying eggs matching the egg appearance of parrotbill hosts?, Canchao Yang; Fugo Takasu; Wei Liang; Anders P. Moller, The coevolutionary interaction between cuckoos and their hosts has been studied for a long time, but to date some puzzles still remain unsolved. Whether cuckoos parasitize their hosts by laying eggs randomly or matching the egg morphs of their hosts is one of the mysteries of the cuckoo problem. Scientists tend to believe that cuckoos lay eggs matching the appearance of host eggs due to selection caused by the ability of the hosts to recognize their own eggs. In this paper, we first review previous empirical studies to test this mystery and found no studies have provided direct evidence of cuckoos choosing to parasitize host nests where egg color and pattern match. We then present examples of unmatched cuckoo eggs in host nests and key life history traits of cuckoos, e.g. secretive behavior and rapid egg-laying and link them to cuckoo egg laying behavior. Finally we develop a conceptual model to demonstrate the egg laying behaviour of cuckoos and propose an empirical test that can provide direct evidence of the egg-laying properties of female cuckoos. We speculate that the degree of egg matching between cuckoo eggs and those of the host as detected by humans is caused by the ability of the hosts to recognize their own eggs, rather than the selection of matching host eggs by cuckoos. The case of Common Cuckoos (Cuculus canorus) and their parrotbill hosts (Paradoxornis alphonsianus), where it has been shown that both have evolved polymorphic eggs (mainly blue and white), was used to develop a conceptual model to demonstrate why cuckoos should utilize parrotbill hosts by laying eggs randomly rather than laying eggs matching the appearance of host eggs. In conclusion, we found no evidence for the hypothesis that cuckoos lay eggs based on own egg color matching that of the parrotbill-cuckoo system. We argue theoretically that laying eggs matching those of the hosts in this system violates a key trait of the life history of cuckoos and therefore should be maladaptive., Apr. 2015, 6, 5, 10.1186/s40657-015-0014-1

  DOI URL
• Refereed, WILDLIFE BIOLOGY, WILDLIFE BIOLOGY, Population viability analysis of the Japanese rock ptarmigan Lagopus muta japonica in Japan, Ayaka Suzuki; Atsushi Kobayashi; Hiroshi Nakamura; Fugo Takasu, The Japanese rock ptarmigan Lagopus muta japonica breeds only in limited alpine areas at high elevations (> 2,500 m a.s.1.) in Japan. The estimated population size is about 2,000 birds and their breeding distribution is subdivided into several local areas, in each of which they may be at risk of local extinction. We estimated age-specific demographic parameters of the core population breeding on Mt. Norikura in Gifu and Nagano prefecture in Japan. We also estimated population viability using deterministic and stochastic population models. Age-specific fertility (the number of female offspring that survived to the next breeding season per female) was 0.417 +/- 0.086, 0.490 +/- 0.080, 0.513 +/- 0.153, 0.435 +/- 0.078, 0.562 +/- 0.139, 0.580 +/- 0.122 (mean SE) for ages 1-6 +, respectively. The annual survival rate was 0.739 +/- 0.047, 0.624 +/- 0.064, 0.513 +/- .087, 0.732 +/- 0.151, 0.447 +/- 0.220, 0.486 +/- 0.089. The population growth rate, evaluated by use of a deterministic projection-matrix model, predicted a stable population, lambda= 1.105 +/- 0.063, 95% CI = 0.985-1.231 and lambda= 1.114 +/- 0.062, 0.996-1.239, using two different assumptions for the final age of reproduction by ptarmigan. We evaluated the risk of extinction as the proportion of Xs that was <= 1, and this was <= 4.4%. To complement the deterministic model, we developed an individual-based stochastic population model in which each of the individuals produced a variable number of offspring and survived one year with certain probabilities that were drawn from estimated distributions of age-specific clutch size and survival rates. Averaged population growth rate under the stochastic model was lambda= 1.1, and the risk of extinction defined as the proportion of trials in which population size <= 1 within 30 years was <= 8.9%, even when the starting population was small (15 birds). These results suggest that the local population at Mt. Norikura is stable in size and suffers a relatively low risk of extinction. We suggest that this population can serve as a potential source for surrounding small local populations that may be sink populations., Dec. 2013, 19, 4, 339, 346, Scientific journal
• Refereed, ANIMAL COGNITION, SPRINGER HEIDELBERG, Egg arrangement in avian clutches covaries with the rejection of foreign eggs, Lenka Polacikova; Fugo Takasu; Bard G. Stokke; Arne Moksnes; Eivin Roskaft; Phillip Cassey; Mark E. Hauber; Tomas Grim, In birds, the colour, maculation, shape, and size of their eggs play critical roles in discrimination of foreign eggs in the clutch. So far, however, no study has examined the role of egg arrangement within a clutch on host rejection responses. We predicted that individual females which maintain consistent egg arrangements within their clutch would be better able to detect and reject foreign eggs than females without a consistent egg arrangement (i.e. whose eggs change positions more often across incubation). We tested this "egg arrangement hypothesis" in blackbirds (Turdus merula) and song thrush (T. philomelos). Both species are suitable candidates for research on egg rejection, because they show high inter-individual variation and individual repeatability in egg rejection responses. As predicted, using our custom-defined metrics of egg arrangement, rejecter females' clutches showed significantly more consistent patterns in egg arrangement than acceptor females' clutches. Only parameters related to blunt pole showed consistent differences between rejecters and acceptors. This finding makes biological sense because it is already known that song thrush use blunt pole cues to reject foreign eggs. We propose that a disturbance of the original egg arrangement pattern by the laying parasite may alert host females that maintain a consistent egg arrangement to the risk of having been parasitized. Once alerted, these hosts may shift their discrimination thresholds to be more restrictive so as to reject a foreign egg with higher probability. Future studies will benefit from experimentally testing whether these two and other parasitized rejecter host species may rely on the use of consistent egg arrangements as a component of their anti-parasitic defence mechanisms., Sep. 2013, 16, 5, 819, 828, Scientific journal, 10.1007/s10071-013-0615-1

  DOI URL
• Refereed, PLOS ONE, PUBLIC LIBRARY SCIENCE, Dynamic Regulation of Myosin Light Chain Phosphorylation by Rho-kinase, Takako Kaneko-Kawano; Fugo Takasu; Honda Naoki; Yuichi Sakumura; Shin Ishii; Takahiro Ueba; Akinori Eiyama; Aiko Okada; Yoji Kawano; Kenji Suzuki, Myosin light chain (MLC) phosphorylation plays important roles in various cellular functions such as cellular morphogenesis, motility, and smooth muscle contraction. MLC phosphorylation is determined by the balance between activities of Rho-associated kinase (Rho-kinase) and myosin phosphatase. An impaired balance between Rho-kinase and myosin phosphatase activities induces the abnormal sustained phosphorylation of MLC, which contributes to the pathogenesis of certain vascular diseases, such as vasospasm and hypertension. However, the dynamic principle of the system underlying the regulation of MLC phosphorylation remains to be clarified. Here, to elucidate this dynamic principle whereby Rho-kinase regulates MLC phosphorylation, we developed a mathematical model based on the behavior of thrombin-dependent MLC phosphorylation, which is regulated by the Rho-kinase signaling network. Through analyzing our mathematical model, we predict that MLC phosphorylation and myosin phosphatase activity exhibit bistability, and that a novel signaling pathway leading to the auto-activation of myosin phosphatase is required for the regulatory system of MLC phosphorylation. In addition, on the basis of experimental data, we propose that the auto-activation pathway of myosin phosphatase occurs in vivo. These results indicate that bistability of myosin phosphatase activity is responsible for the bistability of MLC phosphorylation, and the sustained phosphorylation of MLC is attributed to this feature of bistability., Jun. 2012, 7, 6, e39269. doi:10.1371/journal.po, Scientific journal, 10.1371/journal.pone.0039269

  DOI URL
• Refereed, JOURNAL OF EVOLUTIONARY BIOLOGY, WILEY-BLACKWELL, Modelling the maintenance of egg polymorphism in avian brood parasites and their hosts, W. Liang; C. Yang; B. G. Stokke; A. Antonov; F. Fossoy; J. R. Vikan; A. Moksnes; E. Roskaft; J. A. Shykoff; A. P. Moller; F. Takasu, In avian brood parasitism, egg phenotype plays a key role for both host and parasite reproduction. Several parrotbill species of the genus Paradoxornis are parasitized by the common cuckoo Cuculus canorus, and clear polymorphism in egg phenotype is observed. In this article, we develop a population genetics model in order to identify the key parameters that control the maintenance of egg polymorphism. The model analyses show that egg polymorphism can be maintained either statically as an equilibrium or dynamically with frequency oscillations depending on the sensitivity of the host against unlike eggs and how the parasite targets host nests with specific egg phenotypes. On the basis of the model, we discuss egg polymorphism observed in parrotbills and other host species parasitized by the cuckoo. We suggest the possibility that frequencies of egg phenotypes oscillate and we appeal for monitoring of cuckoohost interactions over a large spatiotemporal scale., May 2012, 25, 5, 916, 929, Scientific journal, 10.1111/j.1420-9101.2012.02484.x

  DOI URL
• Refereed, BEHAVIORAL ECOLOGY, OXFORD UNIV PRESS INC, Sex roles in egg recognition and egg polymorphism in avian brood parasitism, Wei Liang; Canchao Yang; Anton Antonov; Frode Fossoy; Bard G. Stokke; Arne Moksnes; Eivin Roskaft; Jacqui A. Shykoff; Anders P. Moller; Fugo Takasu, Avian brood parasites impose strong selection on their hosts leading to the evolution of antiparasite defenses like egg recognition and rejection. Discordance and template-based cognitive mechanisms may form the base for egg recognition by hosts. For discordance, hosts recognize eggs that constitute the minority in a clutch as alien, whereas in template-based recognition, hosts recognize eggs as alien when they do not match a template that can be innate or learnt. Template-based recognition by learning can be compromised in host species with polymorphic egg color like Paradoxornis parrotbills, hosts of the common cuckoo Cuculus canorus, because a male that learns an egg color in his first breeding attempt can subsequently mate with females having different colors and therefore reject his own eggs. We present a simple conceptual model to understand how an asymmetry in sex roles of care for eggs and egg polymorphism influence the evolution of egg recognition by hosts. We derive host reproductive success in the presence of variation in egg phenotype for both host and parasite. Our model shows that male recognition by learning is disadvantageous unless the host has monomorphic eggs. We suggest that interclutch variation in egg phenotype is the key to understanding the evolution of egg recognition and the sex involved., Mar. 2012, 23, 2, 397, 402, Scientific journal, 10.1093/beheco/arr203

  DOI URL
• Refereed, Zoology, Dr. Mar?a-Dolores Garc?a (Ed.), ISBN: 978-953-51-0360-8, InTech, Development of an individual-based simulation model for the spread of citrus greening disease by the vector insect Diaphorina citri, TAKASU Fugo; Youichi Kobori; Fugo Takasu; Yasuo Ohto, 2012, 87-102
• Refereed, Chinese Birds, Cuckoo parasitism on two closely-related Acrocephalus warblers in distant areas: a case of parallel coevolution?, TAKASU Fugo; Csaba Mosk?t; Fugo Takasu; A. Roman Mu?oz; Hiroshi Nakamura; Mikl?s B?n; Zolt?n Barta, 2012, 3, 4, 320-329, 10.5122/cbirds.2012.0038

  DOI URL
• Refereed, 野生復帰, 日本におけるコウノトリの再導入個体群の存続可能性分析, TAKASU Fugo, 2012, 2, 1-6
• Refereed, JOURNAL OF ZOOLOGY, WILEY-BLACKWELL, The analysis of common cuckoo's egg shape in relation to its hosts' in two geographically distant areas, M. Ban; Z. Barta; A. R. Munoz; F. Takasu; H. Nakamura; C. Moskat, Evolutionary adaptations are required by common cuckoos Cuculus canorus to match host eggs. Hosts may discriminate against alien eggs; hence, accurate matching of the parasite egg to the hosts' is essential. Egg shape is the least-studied component of egg mimicry, and it may also have other functions: an optimal egg shape is necessary for effective incubation. For this reason, cuckoo eggs may show a wide range of variations in shape to a set of host species. Here, we compare cuckoo and host eggs by using egg shape parameters in two distant areas: from the nests of great reed warblers Acrocephalus arundinaceus, robins Erithacus rubecula and marsh warblers Acrocephalus palustris in Hungary, and oriental reed warblers Acrocephalus orientalis, bull-headed shrikes Lanius bucephalus and black-faced buntings Emberiza spodocephala from Japan. Our results suggest the lack of evolutionary adaptation of different cuckoo gentes to their corresponding hosts in terms of egg shape. However, our analyses revealed that cuckoo eggs showed a geographical difference in egg shape., Jun. 2011, 284, 2, 77, 83, Scientific journal, 10.1111/j.1469-7998.2011.00795.x

  DOI URL
• Refereed, JOURNAL OF EVOLUTIONARY BIOLOGY, WILEY-BLACKWELL, Isolation by time and habitat and coexistence of distinct host races of the common cuckoo, A. P. Moller; A. Antonov; B. G. Stokke; F. Fossoy; A. Moksnes; E. Roskaft; F. Takasu, Isolation by time occurs when different populations of a single species reproduce at different times and thereby reduce the probability of interbreeding, potentially causing divergent adaptation to timing of reproduction, eventually resulting in ecological species separated by timing of reproduction. We analysed extensive data on timing of reproduction by different host races of the common cuckoo Cuculus canorus that is an obligate brood parasite laying eggs in the nests of many different species of passerine birds. Because different hosts breed at different times, specific host races of cuckoos have adapted to specific hosts by laying eggs when nests of these hosts are available, and such divergence may be further exaggerated by differences in timing of breeding among host races with similar habitat requirements. Host species accounted for a quarter of the variance in timing of breeding by the cuckoo. Common cuckoos reproduced at a similar, but narrower subset of dates as did possible hosts, showing that only a fraction of hosts with specific breeding dates were parasitized. Common cuckoo eggs laid in the 'right' kind of nests, phenotypically matching the eggs of the host, were laid later during the season than cuckoo eggs laid in the 'wrong' kind of nests where the eggs did not mimic those of the host. Pairs of sympatric cuckoo host races differed more in timing of breeding than pairs of allopatric host races, and pairs of cuckoo host races with similar breeding habitat differed more in breeding date than pairs of cuckoo host races with dissimilar habitat, as expected from reproductive character displacement. These findings are consistent with cuckoo host races being isolated by timing of breeding and habitat., Mar. 2011, 24, 3, 676, 684, Scientific journal, 10.1111/j.1420-9101.2010.02202.x

  DOI URL
• Refereed, APPLIED ENTOMOLOGY AND ZOOLOGY, SPRINGER TOKYO, Dispersal of adult Asian citrus psyllid, Diaphorina citri Kuwayama (Homoptera: Psyllidae), the vector of citrus greening disease, in artificial release experiments, Youichi Kobori; Tadafumi Nakata; Yasuo Ohto; Fugo Takasu, Artificial release of marked adult Diaphorina citri, the insect vector of citrus greening disease, was performed in July 2007 (10,000 adults released, experiment 1) and October 2008 (1,000 adults released, experiment 2) to determine the association of the dispersal pattern with disease invasion risk. During the experimental periods, in experiment 1, the mean dispersal distances from the release point were 5-6 m and in experiment 2 they were 6-12 m. Further examination of the relationship between dispersal distance and season is needed. The number of released D. citri declined with increasing distance from the release point and did not change markedly with time. The center of distribution moved little during the experimental period. These results suggest that the adult D. citri barely moved once they had colonized a host plant within a few days after their release. Our results also suggest that the released D. citri moved with the wind. The diffusion coefficient was estimated at 7.23 from experiment 1, but random diffusion might be a poor descriptor of the dispersal of adult D. citri., Feb. 2011, 46, 1, 27, 30, Scientific journal, 10.1007/s13355-010-0004-z

  DOI URL
• Refereed, POPULATION ECOLOGY, SPRINGER JAPAN KK, Modeling the consequence of increased host tolerance toward avian brood parasitism, Fugo Takasu; Csaba Moskat, Avian brood parasites greatly reduce the reproductive success of their hosts. Empirical studies have demonstrated that some hosts have evolved defenses against parasitism like an ability to recognize and reject parasitic eggs that are dissimilar to their own eggs. Detailed mechanisms of how hosts recognize parasitism still remain unknown, but recent studies have shown that the host's recognition, in many cases, is based on discordance of the eggs in a clutch, and that hosts are more error-prone when the nest is multiply parasitized, i.e., hosts tend to accept more multiple parasitism than single parasitism. In an area in Hungary, the great reed warbler Acrocephalus arundinaceus, one of the main hosts of the common cuckoo Cuculus canorus, is heavily parasitized and the parasitism rate has been kept at quite a high level for decades. Previous mathematical models suggest that such a high parasitism rate can be maintained because the focal host population behaves as a sink where few hosts can reproduce but immigration from outside replenishes the loss of host reproduction in the sink population. Here, we explore the consequences of the increased host tolerance towards multiple parasitism which has been overlooked in the previous studies using a simple model. Our model analysis shows that the increased host tolerance can dramatically contribute to both the parasite abundance and the parasitism rate being kept at a high level. We suggest that such a host behavior, combined with host immigration, can be an important factor responsible for the observed severe parasitism., Jan. 2011, 53, 1, 187, 193, Scientific journal, 10.1007/s10144-010-0221-x

  DOI URL
• Refereed, PLOS ONE, PUBLIC LIBRARY SCIENCE, Coevolution in Action: Disruptive Selection on Egg Colour in an Avian Brood Parasite and Its Host, Canchao Yang; Wei Liang; Yan Cai; Suhua Shi; Fugo Takasu; Anders P. Moller; Anton Antonov; Frode Fossoy; Arne Moksnes; Eivin Roskaft; Bard G. Stokke, Background: Trait polymorphism can evolve as a consequence of frequency-dependent selection. Coevolutionary interactions between hosts and parasites may lead to selection on both to evolve extreme phenotypes deviating from the norm, through disruptive selection. Methodology/Principal finding: Here, we show through detailed field studies and experimental procedures that the ashy-throated parrotbill (Paradoxornis alphonsianus) and its avian brood parasite, the common cuckoo (Cuculus canorus), have both evolved egg polymorphism manifested in discrete immaculate white, pale blue, and blue egg phenotypes within a single population. In this host-parasite system the most common egg colours were white and blue, with no significant difference in parasitism rates between hosts laying eggs of either colour. Furthermore, selection on parasites for countering the evolution of host egg types appears to be strong, since ashy-throated parrotbills have evolved rejection abilities for even partially mimetic eggs. Conclusions/Significance: The parrotbill-cuckoo system constitutes a clear outcome of disruptive selection on both host and parasite egg phenotypes driven by coevolution, due to the cost of parasitism in the host and by host defences in the parasite. The present study is to our knowledge the first to report the influence of disruptive selection on evolution of discrete phenotypes in both parasite and host traits in an avian brood parasitism system., May 2010, 5, 5, e10816. doi:10.1371/journal.po, Scientific journal, 10.1371/journal.pone.0010816

  DOI URL
• Refereed, BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, WILEY-BLACKWELL, Adaptations in the common cuckoo (Cuculus canorus) to host eggs in a multiple-hosts system of brood parasitism, Fugo Takasu; Csaba Moskat; A. Roman Munoz; Sadao Imanishi; Hiroshi Nakamura, The common cuckoo Cuculus canorus parasitism greatly reduces the reproductive success of its hosts and imposes strong selection pressure for hosts to evolve defences against parasitism, such as the ability to recognize and reject dissimilar parasitic eggs, which, in turn, selects for better egg mimicry by the cuckoo. In the co-evolutionary interaction, however, it remains unknown how the cuckoo successfully expanded its range of host usage and how they developed egg mimicry. Most previous studies were conducted in areas where a very few number of host species (i.e. one or two at most) are sympatric with the cuckoo. Several host species, however, breed sympatric with the cuckoo and have been parasitized in the study site in Nagano, central Japan. Such a multiple-hosts system will provide valuable insights for understanding the cuckoo-hosts interactions in the past. In the present study, we report quantitative profiles of eggs based on spectrometer reflectance for four major host species and the corresponding cuckoo gentes. The hosts include the oriental reed warbler (Acrocephalus orientalis), bull-headed shrike (Lanius bucephalus), azure-winged magpie (Cyanopica cyana), and black-faced bunting (Emberiza spodocephala). We show that (1) egg morphs of each host and corresponding cuckoo gens can be categorized by two chromatic components of reflectance spectra and (2) there is a significant difference in a particular chroma component between hosts and the cuckoo. We suggest that the cuckoo parasitism in central Japan originated from parasitism on the black-faced bunting. (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 291-300., Oct. 2009, 98, 2, 291, 300, Scientific journal
• Refereed, POPULATION ECOLOGY, SPRINGER TOKYO, Individual-based modeling of the spread of pine wilt disease: vector beetle dispersal and the Allee effect, Fugo Takasu, Pine wilt disease is caused by the pinewood nematode Bursaphelenchus xylophilus, which is vectored by the Japanese pine sawyer beetle Monochamus alternatus. Due to their mutualistic relationship, according to which the nematode weakens and makes trees available for beetle reproduction and the beetle in turn carries and transmits the nematode to healthy pine trees, this disease has resulted in severe damage to pine trees in Japan in recent decades. Previous studies have worked on modeling of population dynamics of the vector beetle and the pine tree to explore spatial expansion of the disease using an integro-difference equation with a dispersal kernel that describes beetle mobility over space. In this paper, I revisit these previous models but retaining individuality: by considering mechanistic interactions at the individual level it is shown that the Allee effect, an increasing per-capita growth rate as population abundance increases, can arise in the beetle dynamics because of the necessity for beetles to contact pine trees at least twice to reproduce successfully. The incubation period after which a tree contacted by a first beetle becomes ready for beetle oviposition by later beetles is crucial for the emergence of this Allee effect. It is also shown, however, that the strength of this Allee effect depends strongly on biological mechanistic properties, especially on beetle mobility. Realistic individual-based modeling highlights the importance of how spatial scales are dealt with in mathematical models. The link between mechanistic individual-based modeling and conventional analytical approaches is also discussed., Jul. 2009, 51, 3, 399, 409, Scientific journal, 10.1007/s10144-009-0145-5

  DOI URL
• Refereed, EVOLUTION, WILEY-BLACKWELL, The importance of clutch characteristics and learning for antiparasite adaptations in hosts of avian brood parasites, Bard G. Stokke; Fugo Takasu; Arne Moksnes; Eivin Roskaft, There is considerable variation in rejection rates of parasitic eggs among hosts of avian brood parasites. In this article, we develop a model that can be used to predict host egg rejection behavior in brood parasite-host systems in general, by considering both intra- and interclutch variation in host egg appearance; clutch characteristics that may be important in calculating the fitness of individuals adopting rejecter or acceptor strategies. In addition, we consider the importance of learning the appearance of own eggs during the first breeding attempt and host probability of survival between breeding seasons on evolution of rejection behavior. Based on this model we can predict at which level of parasitism fitness of rejecter individuals is higher than that of acceptor individuals and vice versa. The model analyses show that variation in egg appearance can be a key factor for the evolution of host defense against parasitism. In more detail, analyses show that we should expect to find a prolonged learning period only in hosts that have a high intraclutch variation in egg appearance, because such hosts may potentially experience high costs in terms of recognition errors. Furthermore, learning is in general more adaptive in parasite-host systems in which hosts do have some reproductive success even when parasitized, and when parasitism rates are moderate. By including variables that have not been considered in previous models, our model represents a useful tool in investigations of host rejection behavior in various host-parasite systems., Sep. 2007, 61, 9, 2212, 2228
• Refereed, AUK, AMER ORNITHOLOGISTS UNION, Nest light environment and the potential risk of common cuckoo (Cuculus canorus) parasitism, A. Roman Munoz; Maria Altamirano; Fugo Takasu; Hiroshi Nakamura, Brood parasitism represents a significant cost in reproduction; thus, natural selection should favor the evolution of host defenses, which in turn may favor evolution of more sophisticated techniques by the parasite to overcome host defenses. These host defenses include egg rejection, attacking parasites near the nest, and avoiding parasitism by concealing nest sites. In all these antiparasitism strategies, nest light environment may play an important role. In the present study, the risk of Common Cuckoo (Cuculus canorus) parasitism for the Great Reed Warbler (Acrocephalus arundinaceus) was modeled in relation to the in situ nest light environment, from far ultraviolet (UV) to infrared (IR) radiation (280-1,100 nm), and nest situation and structure. The percentage of photosynthetically active radiation (PAR) plus IR radiation (400-1,100 nm) falling on the nest, maximum nest width, and distance between the nest and the nearest active conspecific neighbor were significantly related to the risk of parasitism. Photosynthetically active radiation alone explained 65% of variation in parasitism risk in the final model. Although solar radiation levels in nests were low (<4%. for UV-B and UV-A radiation, 5% for PAR, and 22% for PAR plus IR radiation when cloudless), UV-B, UV-A, and visible-plus-IR radiation levels were significantly lower in nonparasitized nests. These findings provide the first evidence of a relationship between parasitism risk and nest concealment related to microhabitat light environment, with brighter nests suffering a higher risk of parasitism., Apr. 2007, 124, 2, 619, 627, Scientific journal
• Refereed, BEHAVIORAL ECOLOGY, OXFORD UNIV PRESS INC, Importance of spatial habitat structure on establishment of host defenses against brood parasitism, Eivin Roskaft; Fugo Takasu; Arne Moksnes; Bard Gunnar Stokke, We used metapopulation dynamics to develop a mathematical simulation model for brood parasites and their hosts in order to investigate the validity of the "spatial habitat structure hypothesis," which states that a low level of parasite egg rejection in host populations is due to the immigration of acceptor individuals from nonparasitized populations. In our model, we varied dispersal rate and the relative carrying capacity of host individuals in parasitized and unparasitized patches. When both the relative carrying capacity in the parasite-free patch and the dispersal rate increase, the nonparasitized patch will provide more acceptor individuals to the parasite-prone patch. As the relative carrying capacity in the parasite-free patch increases, the equilibrium frequency of rejecters both in the parasite-prone and in the parasite-free patch decreases toward zero for intermediate levels of the dispersal rate. Although the rejecter strategy is more adaptive than the acceptor strategy in the parasite-prone patch, large numbers of acceptors are produced in the parasite-free patch dispersing to the parasitized patch. As the number of individuals in the parasite-free patch increases, parasitism rate can be maintained stable at a high equilibrium level in the parasite-prone patch., Sep. 2006, 17, 5, 700, 708, Scientific journal, 10.1093/beheco/ark019

  DOI URL
• Refereed, Ecological Research, How does stochasticity in colonization accelerate the speed of invasion in a cellular automaton model?, TAKASU Fugo; Kawasaki, K; F. Takasu; H. Caswell; N. Shigesada, Mar. 2006, 21, 334-354
• Refereed, Ornithological Science, A theoretical consideration on coevolutionary interactions between avian brood parasites and their hosts, Fugo Takasu, It has been suggested that parasitic interactions in general result in coevolutionary arms races where parasites and hosts evolve adaptive behaviours and traits to maximize their fitness in a conflicting manner. Avian brood parasitism provides an ideal system for the study of such coevolutionary interactions. In this paper I show and discuss possible consequences of the coevolutionary arms race inherent in avian brood parasitism, especially focusing on egg appearance, a key factor for the reproduction of both hosts and parasites. In such an arms race, hosts evolve the ability to recognize and hence to reject dissimilar parasitic eggs, while parasites counter host defences by more closely mimicking their eggs. Egg mimicry by parasites might then be de-stabilized by hosts changing the appearance of their eggs, thus exposing the mimics. The evolutionary trajectory of the arms race varies depending on the specific detailed mode of interaction between parasite and host individuals. Mathematical modeling, as an important parallel approach to empirical study, helps point the way for further study of avian brood parasitism so as to better understand coevolution in general. © 2005, The Ornithological Society of Japan. All rights reserved., 2005, 4, 1, 65, 72, Scientific journal, 10.2326/osj.4.65

  DOI URL
• Not Refereed, POPULATION ECOLOGY, SPRINGER TOKYO, How many eggs should be laid in one's own nest and others' in intra-specific brood parasitism?, F Takasu, Recent field studies have demonstrated that many bird species practice intra-specific brood parasitism. They lay eggs in the nests of other individuals of the same species, let the foster parents rear their offspring and avoid the cost of parental care. It has been shown that many birds, including starlings, swallows and geese, practice intra-specific brood parasitism in various forms. Intra-specific brood parasitism can be viewed in terms of optimal resource allocation: how many eggs should be put in the nests of other individuals under the risk of being parasitized by others. The situation here is a "game", because the fitness of a parasitic individual depends on how other individuals behave (how many individuals practice parasitism and to what extent). The ecology of intra-specific brood parasitism has been investigated extensively by field ornithologists recently and it is full of material for modeling population/evolutionary biology. In this paper, I present a simple individual-based model to challenge the resource allocation problem in intra-specific brood parasitism. Previous theoretical studies of intra-specific brood parasitism have been based on ESS or quantitative genetics models, where a population is implicitly assumed to be homogeneous and the distribution form of the trait being studied (the allocation rate or the number of eggs laid parasitically) is inherently monomorphic. This paper aims to explore the evolution of intra-specific brood parasitism without these restrictions. In the model, an individual is assigned a strategy, an allocation ratio of eggs that are laid parasitically in the nests of other individuals, and the strategy is inherited by offspring either asexually or sexually. Based on the simulation analysis, the evolution of the allocation rate (the extent of intra-specific brood parasitism) is discussed. The extension of this model to a tractable analytical model is also discussed., Dec. 2004, 46, 3, 221, 229, Scientific journal, 10.1007/s10144-004-0192-x

  DOI URL
• Not Refereed, Proceeding of the Fourth International Congress of Nematology, E J BRILL, Modelling the range expansion of pine wilt disease, Yukie Mimura; Kohkichi Kawasaki; Fugo Takasu; Katsumi Togashi; Nanako Shigesada, Pine wilt disease is caused by pinewood nematode (PWN), Bursaphelenchus xylophilus. The pine sawyer beetle, Monochamus alternatus, in a relationship of obligatory mutalism, vectors this nematode. For more than a century pine wilt disease has spread throughout much of Japan, and in recent times intense management efforts have been taken. These management strategies, however, have not been overly efficient. In this study, we have constructed a mathematical model to describe the spatial-temporal spread of pine wilt disease as a way to investigate the dependency of the range expansion speed (RES) of the disease on the eradication of the vector insect and the patch size of pine stands. We assume that beetles are eradicated at a rate theta only where the infected pine density is larger than a threshold, H-T and investigate how the range expansion speed changes with varying values of theta and H-T. Moreover, we change the patch size of pine stands, with the total area of pine stands being kept constant. The main results are as follows: i) as the eradication rate, theta, increases, the RES initially decreases gradually and then suddenly drops to zero at a certain value of theta; ii) it is impossible to eradicate the disease regardless of the value of theta, when the threshold of the infected pine density, H-T, exceeds a certain value; iii) as H-T decreases, the RES initially shows a gradual decrease and then suddenly drops to zero at a certain value of H-T; iv) it is impossible to eradicate pine wilt disease regardless of the value of H-T, when theta is below a certain value; and v) as the patch size of pine stands becomes larger, the RES increases., 2004, 2, 843, 853, International conference proceedings
• Not Refereed, JOURNAL OF ETHOLOGY, SPRINGER JAPAN KK, Survival and anti-parasite defense in a host metapopulation under heavy brood parasitism: a source-sink dynamic model, L Barabas; B Gilicze; F Takasu; C Moskat, The obligate brood parasite common cuckoo Cuculus canorus, widespread in Eurasia, occasionally reaches a high parasitism rate (over 20%), which usually exists only for a short period of time and in cases of new parasitism. Recent results from Hungary proved that a remarkably high parasitism rate (50-66%) can also be maintained constantly for several decades. In this paradoxical situation the reproductive success of the strongly exploited host population is lower than would be necessary for self-reproduction. We developed a model for a hypothetical host-brood parasite system that demonstrated that immigration of naive individuals from a highly reproductive ("source") host population might explain the survival of the highly parasitized ("sink") population. Our results also showed the possibility of maintaining the high parasitism rate and the imperfection of the host's counter-adaptation against the brood parasite over a longer period. Gene flow was necessary to maintain both the acceptor genes and the non-mimetic cuckoo eggs in heavy parasitism. When the immigration rate was low (1-2%), an early expansion of the mimetic cuckoos was followed by a spread of anti-parasite defense, and consequently, the parasitism rate stabilized at a lower, but still relatively high level of about 45-60%., 2004, 22, 2, 143, 151, Scientific journal, 10.1007/s10164-003-0114-y

  DOI URL
• Not Refereed, POPULATION ECOLOGY, SPRINGER-VERLAG TOKYO, How does spatio-temporal disturbance influence species diversity in a hierarchical competitive system? Prospective order of species coexistence and extinction, K Ohsawa; K Kawasaki; F Takasu; N Shigesada, To address how habitat destruction and hierarchical competition among species affect the spatio-temporal dynamics of a multi-species community, we present a compartment model in which multiple species undergo dispersal and competitive interactions in a patchy habitat arranged in a two-dimensional lattice. We assume that disturbances are periodically imposed on some parts of the lattice in a block, followed by a period free of disturbance. For convenience, species are ranked in order of competitive ability. We further assume that the intrinsic growth rate of species i, epsilon(i), and the dispersal ability, D-i, increase in decreasing order of rank. Our model can analytically determine the exact number of surviving species when disturbance is absent. In the presence of disturbance, we numerically examine how spatio-temporal changes in environmental heterogeneity affect species coexistence and extinction, for the case in which the value of epsilon(i)/D-i monotonically increases or decreases with rank. The results demonstrate that (1) when the interspecific competition is smaller than the intraspecific competition, we can provide predictions on the prospective order of species to be driven extinct and the order of potential species to revive with increasing extents of disturbance; (2) when the interspecific competition is stronger than intraspecific competition, a small difference in the disturbance level can lead to drastic changes in the species composition, their densities and the order of species extinction. In addition, comparison with other similar models reveals that differences in species interaction in local population dynamics critically affect the disturbance-mediated species diversity., Dec. 2003, 45, 3, 239, 247, Scientific journal, 10.1007/s10144-003-0165-5

  DOI URL
• Not Refereed, EVOLUTIONARY ECOLOGY RESEARCH, EVOLUTIONARY ECOLOGY LTD, Co-evolutionary dynamics of egg appearance in avian brood parasitism, F Takasu, In avian brood parasitism, interactions between parasites and their hosts lead to a co-evolutionary process called an arms race. Field studies have shown that many host species have evolved an ability to recognize and reject parasite eggs that look unlike their own and that some parasites lay eggs of sophisticated mimicry. Egg appearance is a crucial factor that determines the reproductive success both of the parasites and their hosts in the arms race. The appearance of eggs, however, is a quantitative trait and the variation within a population could critically affect the dynamics of the arms race; parasite individuals that lay eggs more similar to those of the host are more likely to reproduce successfully, whereas host individuals that lay eggs more unlike those of the parasite have a better chance of rejecting parasitism and reproducing, which would de-stabilize the parasites' good mimicry. To explore the arms race for egg appearance, I constructed a model described by an integro-difference equation. The temporal change of the 'distributions' of egg appearance along a continuous spectrum was analysed both for the parasite and host populations. The model analyses show that (1) a conventional view of an arms race-'parasites chasing their hosts escaping from the parasites'-is realized in the early stage of the dynamics, but (2) the distributions of egg appearance finally converge to discrete point-distributions (polymorphism) even when any continuous distributions are used as the initial state. The latter might be relevant to the maintenance of polymorphism of egg appearance. Based on the model analysis, I discuss the implications of this model for general (co)evolutionary processes for quantitative traits and suggest a new modelling framework to account for such processes., Mar. 2003, 5, 3, 345, 362, Scientific journal
• Not Refereed, In: Morphogenesis and Pattern Formation in Biological Systems: Experiments and Models (eds. T.Sekimura, S.Noji, N.Ueno & P.K.Maini). Springer-Verlag Tokyo., Biological invasion into periodically fragmented environments: A diffusion-reaction model., N. Shigesada; N. Kinezaki; K. Kawasaki; F. Takasu, (2003), 2003, 215, 222
• Refereed, Theoretical Population Biology, Modeling biological invasions into periodically fragmented environments（共著）, TAKASU Fugo, 2003, 64, 291-302
• Not Refereed, JOURNAL OF THEORETICAL BIOLOGY, ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, Recurrent habitat disturbance and species diversity in a multiple-competitive species system, K Ohsawa; K Kawasaki; F Takasu; N Shigesada, To address how species interactions, dispersal and environmental disturbances interplay to affect the spatial distribution and diversity of species, we present a compartment model in which multiple species undergo competitive interaction of Lotka-Volterra type in a patchy environment arranged in a square lattice. Dispersal of species occurs between adjacent patches. Disturbances are periodically imposed on a central part of the environment in a belt-like block or an island-like block of various sizes where each species is killed for a certain time interval and then allowed to recover for the rest of a disturbance cycle. We deal with a case in which the local population dynamics within each patch is analytically determinable and has multiple locally stable equilibrium states in the absence of environmental disturbance. We further assume a trade-off between the reproductive rate of species and its dispersal ability. With these settings, we numerically examine how the spatio-temporal distributions of species are affected by changes in the pattern, size and duration of disturbances. The results demonstrate that: (1) in the undisturbed area, environmental disturbances could generate spatially segregated distributions of species; (2) in the disturbed area, species with higher dispersal abilities quickly invade and preferentially recover their population during the post-disturbance period, being temporarily relieved of competition from other species. These mechanisms collectively lead to increased species diversity in the whole habitat, functioning best when both the size and duration of disturbances are intermediate. In particular, the belt-like disturbance is more effective than the island-like disturbance in sustaining spatial heterogeneity for a wider range of duration of disturbance. (C) 2002 Elsevier Science Ltd. All rights reserved., May 2002, 216, 2, 123, 138, Scientific journal, 10.1006/jtbi.2002.2554

  DOI URL
• Not Refereed, BEHAVIORAL ECOLOGY, OXFORD UNIV PRESS INC, Modeling spawning strategy for sex change under social control in haremic angelfishes, Y Hamaguchi; Y Sakai; F Takasu; N Shigesada, In haremic angelfishes where protogynous (female to male) sex change is favored, females have been reported to adopt several tactics for earlier sex change on the basis of a trade-off between reproduction and growth, or survivorship. A recent field study on Centropyge ferrugatus revealed that females reduce spawning frequency in competition with similar-sized neighbors for social dominance. To evaluate the optimal spawning strategy taken by haremic fishes, we developed an evolutionarily stable strategy model that focuses on their life history and social structure based on field data of C. ferrugatus. The results of the analysis predict that the spawning frequency will be low when the mortality rate of females is high compared with males, the harem size is large, and there is a moderate degree of social control. Our model further predicts conditions under which females completely stop spawning, as if they have become bachelors. Thus, the regulated spawning frequency may be taken as a strategy to optimize the reproductive success of an individual in response to the available choices for sex change, social control, and environmental conditions. Social control would also play an important role in sex change in many other haremic species., Jan. 2002, 13, 1, 75, 82, Scientific journal
• Refereed, JAPAN JOURNAL OF INDUSTRIAL AND APPLIED MATHEMATICS, KINOKUNIYA CO LTD, Diffusive waves, dynamical stabilization and spatio-temporal chaos in a community of three competitive species, S Petrovskii; K Kawasaki; F Takasu; N Shigesada, The spatio-temporal dynamics of three competitive species is considered. Mathematically, the community is described by a system of partial differential equations of Lotka-Volterra type. The properties of the system are investigated both numerically and analytically. We show that for finite initial conditions the dynamics of the system is typically reduced to a succession of travelling diffusive waves, some of which demonstrate rather an unusual behaviour. Particularly, a locally unstable equilibrium can become stable in the wake of a diffusive front. After propagation of the waves, the domain is invaded by irregular spatiotemporal population oscillations that can be classified as spatio-temporal chaos., Jun. 2001, 18, 2, 459, 481, Scientific journal
• Refereed, Protection of World Forests from Insect Pests: Advances in Research (eds. H. Evans & A. Liebhold) IUFRO World Series, Spatial spread of pine wilt disease : modeling the dispersal distance distribution of the pine sawyer beetle, Monochamus alfernatus（共著）, Nunotani H; K. Kawasaki; F. Takasu; K. Togashi; N. Shigesada, 2001, 11, 79-85
• Refereed, BULLETIN OF MARINE SCIENCE, ROSENSTIEL SCH MAR ATMOS SCI, Morphological plasticity in the coral Porites sillimaniani and its adaptive significance, S Muko; K Kawasaki; K Sakai; F Takasu; N Shigesada, The whole-colony morphology of the coral, Porites sillimaniani, varies dramatically in accordance with light intensity from plate-like shape to branching shape. To determine whether the variation is based on genetic difference or phenotypic plasticity, we conducted a field experiment by transplanting coral fragments taken from seven plate-like colonies to different light conditions. The fragments that transplanted to the high-light condition started to have branches in 8 mo period of the experiment, whereas those to the low-light condition remained to be flat. This result suggests that the morphological variation is the phenotypic plasticity in response to light availability. To examine the adaptive significance of this plasticity a simple mathematical model of coral shape is constructed in which the number of branches, their angles and lengths are morphological parameters. The circumference of the model coral is assumed to be uniformly covered with polyps. Each polyp survives if its light flux is larger than a certain threshold value. The optimal morphology that can support a maximum number of viable polyps is calculated for a given light intensity. The optimal coral shape changes with light intensity, which agrees qualitatively with the observation of P. sillimaniani colony in natural habitats., Jan. 2000, 66, 1, 225, 239, Scientific journal
• Refereed, Biological Invasions, Modeling the expansion of an introduced tree disease, Fugo Takasu; Namiko Yamamoto; Kohkichi Kawasaki; Katsumi Togashi; Yoichi Kishi; Nanako Shigesada, Pine wilt disease is caused by the introduced pinewood nematode, Bursaphelenchus xylophilus, for which the vector is the pine sawyer beetle, Monochamus alternatus. Native Japanese pines, black pine “Pinus thunbergii” and red pine “P. densiflora”, are extremely sensitive to the nematode's infection, and the parasite has been expanding nationwide in the last few decades, despite intensive control efforts. To understand the parasite's range expansion in Japan, we modeled the dynamics of the pines and the beetle that disperses the nematode, using an integro-difference equation in a one-dimensional space. Based on field data collected in Japan, we investigated the dependence of the parasite's rate of range expansion on the eradication rate of the beetle, the initial pine density, and the beetle dispersal ability. Our model predicts several results. “1” The Allee Effect operates on beetle reproduction, and consequently the parasite cannot invade a pine stand, once the beetle density decreases below a threshold. “2” The distribution of the dispersal distance of the beetles critically affects the expansion rate of the disease. As the fraction of the beetles that travel over long distance increases from zero, the range expansion accelerates sharply. “3” However, too frequent long-range dispersal results in a failure of the parasite invasion due to the Allee Effect, suggesting the importance of correctly assessing the beetle's mobility to predict the speed of range expansion of the parasite. “4” As the eradication rate is increased, the range expansion speed decreases gradually at first and suddenly drops to zero at a specific value of the eradication rate., 2000, 2, 2, 141, 150, Scientific journal, 10.1023/A:1010048725497

  DOI URL
• Refereed, JAPANESE JOURNAL OF ECOLOGY, The Ecological Society of Japan, マツ枯れシステムのダイナミクスと大域的伝播の数理解析（共著）, YAMAMOT Namiko; TAKASU Fugo; KAWASAKI Kohkichi; TOGASHI Katsumi; KISHI Youichi; SHIGESADA Nanako, 2000, 50, 3, 269-276, 276, 10.18960/seitai.50.3_269

  PermalinkDOI URL
• Refereed, ECOLOGY, ECOLOGICAL SOC AMER, Modeling the spread of pine wilt disease caused by nematodes with pine sawyers as vector, A Yoshimura; K Kawasaki; F Takasu; K Togashi; K Futai; N Shigesada, An epidemic of pine wilt disease has been spreading in wide areas of Japan for nearly a century. The disease is caused by the pinewood nematode, Bursaphelenchus xylophilus, with the pine sawyer, Monochamus alternatus, as vector. The spread of disease is facilitated by an obligatory mutualism between the nematode and the pine sawyer: the pine sawyer helps the nematode transmit to a new host tree, while the nematode supplies the pine sawyer with newly killed trees on which to lay eggs. We present a mathematical model to describe the host-vector interaction between pines and pine sawyers carrying nematodes, on the basis of detailed data on the population dynamics of pine sawyers and the incidence of pine wilt disease at a study site located on the northwest coast of Japan. We used the model to simulate the dynamics of the disease and predict how the epidemic could be controlled by eradication of the pine sawyer, The main results are as follows: (1) There is a minimum pine density below which the disease always fails in invasion. However, even if the pine density exceeds this minimum, the disease fails in invasion due to the Allee effect when the density of pine sawyers is very low. (2) The: minimum pine density increases disproportionately with increase in the eradication rate. (3) The probability that a healthy tree will escape from infection until the epidemic dies out decreases sharply with increase in the initial pine density or the initial density of pine sawyers., Jul. 1999, 80, 5, 1691, 1702, Scientific journal
• Refereed, Biological Invasions of Ecosystem by Pests and Beneficial organisms, NIAES Series 3, Mathematical models for biological invasions-competition for open spaces（共著）, Takasu F; M. Shiraishi; K. Kawasaki; N. Shigesada, 1999, 78-87
• Refereed, Biological Sciences in Space, Population dynamics of nitrifying bacteria in an aquatic ecosystem(共著), Kubo Y; F. Takasu; R. Shimura; S. Nagaoka; N. Shigesada, 1999, 13, 4, 333-340, 195
• Not Refereed, EVOLUTIONARY ECOLOGY, KLUWER ACADEMIC PUBL, Modelling the arms race in avian brood parasitism, F Takasu, In brood parasitism, interactions between a parasite and its host lead to a co-evolutionary process called an arms race, in which evolutionary progress on one side provokes a further response on the other side. The host evolves defensive means to reduce the impact of parasitism, while the parasite evolves means to counter the host's defence. To gain insights into the co-evolutionary process of the arms race, a model is developed and analysed, in which the host's defence and the parasite's counterdefence are assumed to be genetically determined. First, the effect of parasite counterdefence on host defence is analysed. I show that parasite counterdefence can critically affect the establishment of host defence, giving rise to three situations in the equilibrium state: The host shows (1) no defence, (2) an intermediate level of defence or (3) perfect defence. Based on these results, the evolution of parasite counterdefence is considered in connection with host defence. It is suggested that the parasite can evolve counterdefence to a certain degree, but once it has established counterdefence beyond this, the host gives up its defence against parasitism provided the defence entails some cost to perform. Dynamic aspects of selection pressure are crucial for these results. Based on these results, I propose a hypothetical evolutionary sequence in the arms race, along which interactions between the host and parasite proceed., Nov. 1998, 12, 8, 969, 987, Scientific journal
• Not Refereed, AMERICAN NATURALIST, UNIV CHICAGO PRESS, Why do all host species not show defense against avian brood parasitism: Evolutionary lag or equilibrium?, F Takasu, Avian brood parasitism reduces the reproductive success of hosts and is therefore expected to select for host defenses against parasitism, such as an ability to reject parasitic eggs. Field studies have shown that some hosts recognize and reject parasitism, whereas others do not, and the degree of the defense varies from population to population. One long-standing debate concentrates on the differences in the distribution of host defenses observed in hosts parasitized by the brown-headed cowbird and the common cuckoo. The cowbird's hosts show either few or nearly perfect defenses, whereas the cuckoo's hosts have defenses varying from none to complete, with most falling in between the two extremes. To explore the mechanisms underlying this pattern, I constructed a mathematical model in which host defense is assumed to be genetically determined and analyzed how the host defense is established under parasitic pressure. The model shows that differences in the defense-level distribution can be attributed to the difference in the parasite's breeding strategy, generalized or specialized: hosts parasitized by generalists show perfect, none, or intermediate levels of the defense depending on the host abundances, whereas hosts parasitized by specialists always exhibit either none or intermediate levels of the defense if the parasite lacks counterdefenses such as egg mimicry. This result provides a testable explanation for the existence of accepter species of the brown-headed cowbird, which might reconcile the previously conflicting hypotheses., Feb. 1998, 151, 2, 193, 205, Scientific journal
• Refereed, Forma, Simulation study of Stratitied Diffusion Model（共著）, TAKASU Fugo; KAWASAKI Kohkichi; SHIGESADA Nanako, 1997, 12, 2, 167-175, 175
• Refereed, JAPANESE JOURNAL OF ECOLOGY, The Ecological Society of Japan, 行動と共進化－托卵鳥とその宿主, TAKASU Fugo, 1995, 45, 2, 191-197, 197, 10.18960/seitai.45.2_191

  PermalinkDOI URL
• Refereed, AMERICAN NATURALIST, UNIV CHICAGO PRESS, MODELING THE POPULATION-DYNAMICS OF A CUCKOO-HOST ASSOCIATION AND THE EVOLUTION OF HOST DEFENSES, F TAKASU; K KAWASAKI; H NAKAMURA; JE COHEN; N SHIGESADA, Cuckoo parasitism in Nagano Prefecture in Japan has shown dramatic changes in the parasitism rate, host usage by the cuckoo, and defensive behavior of hosts during the past 60 yr. To gain insights into these phenomena, we model the population dynamics of a cuckoo-host association together with the population genetics of a rejecter gene in the host population. Analysis shows that both the dynamical change in the host-parasite association and the establishment of the host's counteradaptation crucially depend on the product of two factors, the carrying capacity of the host and cuckoo's searching efficiency. When the product is less than a critical value, the host population cannot evolve a counteradaptation even if parasitized by the cuckoo. Hence, the lack of counteradaptation does not necessarily imply that the host population only recently has become parasitized. As the product becomes larger, the rejection behavior will be eventually established at higher levels in the host population. In this case, the spreading of rejection behavior is very fast, which suggests that the cuckoo-host association reaches an equilibrium state within a relatively short period. These results make possible new interpretations of several circumstances reported about cuckoo-host associations., Nov. 1993, 142, 5, 819, 839, Scientific journal
• Refereed, Ornithological Science, Ornithological Society of Japan, Egg Pattern Mimicry in Avian Brood Parasitism Assessed Using Local Image Descriptors and Human-Eyes, Huu Ton Le; Doanh Nguyen-Ngoc; Hoang Tung Tran; Anh Tuan Giang; Edourd Amouroux; Antonio-Román Muñoz; Fugo Takasu, 29 Jul. 2022, 21, 2, Scientific journal, 10.2326/osj.21.189

  DOI URL
• Refereed, Frontiers in Plant Science, Frontiers Media SA, Simulating Pine Wilt Disease Dispersal With an Individual-Based Model Incorporating Individual Movement Patterns of Vector Beetles, Chunlei Xia; Tae-Soo Chon; Fugo Takasu; Won Il Choi; Young-Seuk Park, Individual movements of the insect vector pine sawyer beetles were incorporated into an individual-based model (IBM) to elucidate the dispersal of pine wilt disease (PWD) and demonstrate the effects of control practices. The model results were compared with the spatial data of infested pine trees in the Gijang-gun area of Busan, Republic of Korea. Step functions with long- and middle-distance movements of individual beetles effectively established symptomatic and asymptomatic trees for the dispersal of PWD. Pair correlations and pairwise distances were suitable for evaluating PWD dispersal between model results and field data at short and long scales, respectively. The accordance between model and field data was observed in infestation rates at 0.08 and 0.09 and asymptomatic rates at 0.16–0.17 for disease dispersal. Eradication radii longer than 20 m would effectively control PWD dispersal for symptomatic transmission and 20–40 m for asymptomatic transmission. However, the longer eradication radii were more effective at controlling PWD. Therefore, to maximize control effects, a longer radius of at least 40 m is recommended for clear-cutting eradication. The IBM of individual movement patterns provided practical information on interlinking the levels of individuals and populations and could contribute to the monitoring and management of forest pests where individual movement is important for population dispersal., 23 May 2022, 13, Scientific journal, 10.3389/fpls.2022.886867

  PermalinkDOI URL
• Refereed, Journal of Theoretical Biology, Elsevier BV, Spatial metapopulation dynamics with local and global colonization, Le Dieu Huong; Nguyen Trong Hieu; Fugo Takasu, Sep. 2023, 572, 111579, 111579, Scientific journal, 10.1016/j.jtbi.2023.111579

  DOI URL共同研究・競争的資金等URL

MISC

• Not Refereed, 生物科学, 日本生物科学者協会, フィールド研究と数理モデル研究, TAKASU Fugo, Jan. 2003, 54, 2, 111-118, 118

  Permalink
• Not Refereed, Proceedings of 22nd International Ormthological Congress Adams, N-J. & Slotow, R. H. (eds.), The role of theoretical models explaining the relationships between brood parasites and their hosts, TAKASU Fugo, 1999, 3146-3164
• 日本応用動物昆虫学会大会講演要旨, 個体ベースモデルによる激発地におけるカンキツグリーニング病防除手段の検討, 小堀陽一; 高須夫悟; 大藤泰雄, 2012, 56th
• 日本数理生物学会大会講演要旨集, 個体ベースモデルを活用したカンキツグリーニング病の防除技術開発, 小堀陽一; 高須夫悟; 大藤泰雄, 2012, 22nd
• 日本応用動物昆虫学会大会講演要旨, カンキツグリーニング病の虫媒伝搬による侵入と感染拡大のリスク評価, 小堀陽一; 中田唯文; 大藤泰雄; 高須夫悟, 2010, 54th
• RIMS Kokyuroku, Kyoto University, Modeling of population dynamics as individual-based (Kyoto Winter Research Program in Mathematical Biology Next Wave), Takasu Fugo, Jun. 2009, 1653, 1, 1

  Permalink
• RIMS Kokyuroku, Kyoto University, A MATHEMATICAL MODEL OF THE EVOLUTION OF HOST DEFENSIVE BEHAVIOR IN CUCKOO - HOST ASSOCIATIONS(Mathematical Topics in Biology), TAKASU Fugo; KAWASAKI Kohkichi; COHEN Joel E., Mar. 1993, 827, 146, 155

  Permalink
• IPSJ SIG Notes, Information Processing Society of Japan (IPSJ), Stochasstic integro - difference model for biological invasion, KIMURA Miki; KAWASAKI Kohkichi; TAKASU Fugo; SHIGESADA Nanako, Organisms expand their distribution area, while undergoing dispersal and reproduction. One model describing such spread of organisms is given by the integro-difference equation. In this study, we consider a stochastic model that incorporates stochasticity in both reproduction and dispersal processes within the framework of the deterministic model. We performed computer simulations of this stochastic model and found that the speed in the stochastic model is about 70〜80% less than that in the corresponding deterministic model. We distinguished the stochasticity in growth from that in dispersal on the overall speed. As a result, we found that the speed scarcely changes with the degree of stochasticity in reproduction. Thus we conclude that the delay in speed is caused mainly by stochastic dispersal., 07 May 2004, 2004, 42, 29, 30

  Permalink
• IPSJ SIG Notes, Information Processing Society of Japan (IPSJ), A simulation study on adaptive dynamics of a quantitative trait, YAMADA Satomi; TAKASU Fugo; SIGESADA Nanako, A heritable quantitative trait in general is an expression that results from accumulated small contributions of a certain number of genes at multiple loci. In this study, we analyze both the evolution of a quantitative trait and the consequence of it on the population dynamics. We assume a population where the trait in focus could be either the intrinsic growth rate or the carrying capacity and investigate how the evolution of the trait affects properties of the population dynamics. Furthermore we are curious to know what difference emerges when compared with a realistic model based on stochastic individual-based model. We construct IBM and analyze it by simulation and then derive a deterministic dynamics corresponding to the IBM. The difference between the two models is discussed., 07 May 2004, 2004, 42, 31, 32

  Permalink
• IPSJ SIG Notes, Information Processing Society of Japan (IPSJ), Range Expansion of Invading Species in a Periodically Striped Environment, KINEZAKI Noriko; KAWASAKI Kokichi; TAKASU Fugo; SHIGESADA Nanako, Environments for living organisms are often fragmented by natural or artificial habitat destruction. To simulate the range expansion of a single species in such a heterogeneous environment, we present a diffusion-reaction equation in which the rates of diffusion and reproduction periodically fluctuate between favorable and unfavorable habitats arranged in a striped pattern. Using this model, we derive a mathematical formula for the invasion speed together with the spatio-temporal pattern of range expansion., 10 May 2001, 2001, 37, 19, 22

  PermalinkURL
• IPSJ SIG Notes, Information Processing Society of Japan (IPSJ), Study Of Tterritory Formation By Game Fish Ayu Using Individual Based Model, OKUNO Yumiko; TAKASU Fugo, Game fish Ayu is a fresh water fish in Japan and famous for forming exclusive territory for foraging during the growth period. But not all individuals can own territory when the population density is high. The territory in average covers about 1 m^2 irrespective of the population density, and it contains enough amount of algate, the food resource of Ayu, to sustain the owner of the territory. The evolutionary origin of such territory forming behavior that monopolize unnecessarily abundant amount of food resource by one individual is not still understood well. To get insights to the evolutionary orgin of the territory formation by Ayu, we model behavior of each individual of Ayu by individual based model. Based on the computers simulation, we discuss the origin of the territory formation by Ayu fish., 10 May 2001, 2001, 37, 15, 18

  PermalinkURL

Books etc

• Chapter "Evolution and Maintenance of Egg Rejection by Hosts as Adaptation Against Conspecific Brood Parasites: An Individual-Based Model" in Avian Brood Parasitism, Behaviour, Ecology, Evolution and Coevolution, Springer International Publishing, TAKASU Fugo, 分担, Apr. 2018, Not Refereed
• 招かれない虫たちの話 虫がもたらす健康被害と害虫管理, 第11章「感染症流行の数理的研究」執筆, 東海大学出版部, TAKASU Fugo, 分担, Mar. 2017, Not Refereed, 9784486021254
• 行動生物学辞典, 東京化学同人, TAKASU Fugo, 分担, Nov. 2013, Not Refereed
• シリーズ現代の生態学・第5巻・行動生態学 第5章執筆, 共立出版, TAKASU Fugo, 分担, Jun. 2012, 98- 119, Not Refereed, 9784320057388
• 数理科学事典, 丸善, TAKASU Fugo, 筆頭著者, Nov. 2009, 278-281, Not Refereed
• 個体性を保ったダイナミクスモデル シリーズ 数理生物学要論 巻2「空間」の数理生物学 第6章, 共立出版, TAKASU Fugo, 筆頭著者, May 2009, 第6章, Not Refereed
• オナガの分布域拡大に伴うカッコウとの新たな関係、「鳥の自然史」第6章, 北海道大学出版会, TAKASU Fugo, 分担, 2009, 第6章, Not Refereed
• Phenotypic Evolution, メディカル・サイエンス・インターナショナ, TAKASU Fugo, 分担, 2009, 第20章, Not Refereed
• 持続不可能性 - 環境保全のための複雑系理論入門（共訳）\nFragile Dominion by Simon Levin (1999) Perseus Publishing, Cambridge, Massachusetts, 持続不可能性 - 環境保全のための複雑系理論入門 文一総合出版, TAKASU Fugo, Oct. 2003, 1-376頁, Not Refereed
• リンデンマイヤー・システムとしての植物根系の形態（共著）, 生物の形の多様性と進化 － 遺伝子から生態系まで －\n関村利朗・野地澄晴・森田利仁 共編 裳華房 第14章, TAKASU Fugo, Jun. 2003, 152-162頁, Not Refereed
• 数理生態学と鳥類学－托卵を題材にして－ 第8章執筆（191-222）, これからの鳥類学\n山岸哲・樋口広芳 共編 裳華房, TAKASU Fugo, 2002, 第8章(191-222項), Not Refereed
• 新人口論－生態学的アプローチ\nHow many people can the earth support? Joel. E. Cohen\n共訳, 新人口論－生態学的アプローチ\n農山漁村文化協会, 656 pages, TAKASU Fugo, 1998, Not Refereed

Presentations

• Public symposium, 27 Jun. 2023, 01 Jul. 2023
• Public symposium, 17 Jul. 2023, 20 Jul. 2023
• Public discourse, 28 Aug. 2023, 29 Aug. 2023
• Nominated symposium, 13 Sep. 2023, 14 Sep. 2023
• Nominated symposium, 01 Oct. 2022, 01 Oct. 2022
• Oral presentation, 20 Jul. 2022, 21 Jul. 2022
• Public symposium, 13 Jun. 2021, 17 Jun. 2021
• Public symposium, 25 Nov. 2021, 26 Nov. 2021
• Public symposium, 14 Mar. 2022, 19 Mar. 2022
• Public discourse, 05 Dec. 2019, 05 Dec. 2019
• Public discourse, 03 Dec. 2019, 04 Dec. 2019
• Nominated symposium, 17 Nov. 2019, 18 Nov. 2019
• Public discourse, 12 Nov. 2019, 12 Nov. 2019
• TAKASU Fugo, 日本数理生物学会2019年大会, Spatial metapopulation dynamics as a point pattern dynamics, 16 Sep. 2019
• TAKASU Fugo; Fugo TAKASU, Seminar at the department of mathematics, Dhaka University, Bangladesh, Equilibrium properties of the spatial SIS model as a point pattern dynamics, Feb. 2019, True
• TAKASU Fugo; Fugo TAKASU, Mathematical modeling workshop at EnFRA, Equilibrium properties of the spatial SIS model as a point pattern dynamics, Dec. 2018, EnFRA in Busan, Korea, True
• TAKASU Fugo; Fugo TAKASU, Mini-workshop on the new development of aquatic ecosystem model, An approach to study adaptive community dynamics, Dec. 2018, Hanyang University ERICA, Korea, True
• TAKASU Fugo; Fugo TAKASU, Seminar at the department of biology, Kyung Hee University, Korea, Equilibrium properties of the spatial SIS model as a point pattern dynamics, Dec. 2018, Kyung Hee University, Seoul, Korea, True
• TAKASU Fugo; Fugo TAKASU, Seminar at the department of physics, Inha University, Korea, Equilibrium properties of the spatial SIS model as a point pattern dynamics, Dec. 2018, Inha University, Incheon, Korea, True
• TAKASU Fugo; Fugo TAKASU, The 8th EAFES (East Asian Federation of Ecological Societies) International Congress, Spatial metapopulation dynamics as a point pattern dynamics, Apr. 2018, East Asian Federation of Ecological Societies, Nagoya University, Nagoya, Japan, True
• TAKASU Fugo, 日本生態学会第65回大会, Spatial metapopulation dynamics as a point pattern dynamics, Mar. 2018, 日本生態学会, 札幌コンベンションセンター、札幌市, False
• TAKASU Fugo; Fugo Takasu, Seminar at the School of Mathematics and Statistics of Wuhan University, Spatial population dynamics of biological phenomena, Dec. 2017, School of Mathematics and Statistics of Wuhan University, Wuhan, China, True
• TAKASU Fugo; Fugo Takasu, Seminar at the School of Mathematical Sciences of Soochow University, Mathematical and Computational Approaches to Spatial Modeling in Ecology, Dec. 2017, School of Mathematical Sciences of Soochow University, Suzhou, China, True
• TAKASU Fugo; Fugo Takasu, ISEM 2017 Global Conference Pre-conference short course, Mathematical and computational approaches to spatial modelling in ecology, Sep. 2017, Society of Ecological Modeling, Jeju island, Korea, True
• TAKASU Fugo; Fugo Takasu, ISEM 2017 Global Conference, Jeju, Korea, Modeling the spatial spread spread of the pine wilt disease - how does vector beetle dispersal affect disease expansion?, Sep. 2017, Society of Ecological Modeling, Jeju island, Korea, True
• TAKASU Fugo; Fugo Takasu, Seminar at National Institute of Ecology of Korea, Meta-population dynamics as a stochastic point pattern, Sep. 2017, National Institute of Ecology of Korea, Gunsan, Korea, True
• TAKASU Fugo; Fugo Takasu, VNU NUS Miniworkshop "Selected topics in mathematical modeling", Point pattern dynamics - a challenge to work on spatial population dynamics, Nov. 2016, VNU University of Science, Hanoi, Vietnam, True
• TAKASU Fugo; Fugo Takasu, Symposium - What is a good model? Evidential statistics, information criterion and model evaluation, Spatial population dynamics as a point pattern dynamics, Jan. 2016, 統計数理研究所, True
• TAKASU Fugo; Fugo Takasu, Seminar at the Institute of Forestry and Environmental Science, Chittagong University, Bangladesh, Hidden Markov Model as a tool to study animal behaviors, Nov. 2015, Chittagong University, Bangladesh, True
• TAKASU Fugo, 東京大学大学院数理科学研究科・数理生物学セミナー, Spatial population dynamics as a point pattern dynamics, Nov. 2015, 東京大学駒場キャンパス, False
• TAKASU Fugo; Fugo Takasu, Symposium "Advances in spatial ecology", JSMB CJK 20015, Doshisha University 26- 29 August 2015., Spatial epidemic models as a point pattern dynamics, Aug. 2015, Japan Society for Mathematical Biology, Joint meeting with China, Japan, and Korea 2015, 同志社大学今出川キャンパス, True
• TAKASU Fugo; Fugo Takasu, Seminar talk at the Chinese Academy of Forestry, Beijing, Modeling the spatial spread of the pine wilt disease - an individual-based approach, Jan. 2015, Beijing, China, True
• TAKASU Fugo; Fugo Takasu, Seminar talk at the Institute of Zoology, Chinese Academy of Sciences, Beijing, Modeling the maintenance of egg polymorphism over geographic scale, Jan. 2015, Beijing, China, True
• TAKASU Fugo; Fugo Takasu, Seminar at Kyung Hee University, Seoul, Korea, Modeling the spatial spread of the pine wilt disease - an individual-based approach, Dec. 2014, Seoul, Korea, True
• TAKASU Fugo; Fugo Takasu, Seminar at the Institute of Forestry and Environmental Science of the University of Chittagong, Chittagong, Bangladesh, Modeling spatial spread of infectious disease - an individual-based approach, Nov. 2014, Chittagong, Bangladesh, True
• TAKASU Fugo; Fugo Takasu, Seminar at Busan National University, Busan, Korea, Modeling the spatial spread of the pine wilt disease - an individual-based approach, Nov. 2014, Busan, Korea, True
• TAKASU Fugo; Fugo Takasu, IUFRO 2014, International Union of Forest Research Organizations, Modeling the spatial spread of the pine wilt disease - an individual-based approach, Oct. 2014, Salt Lake City, Utah, USA, True
• TAKASU Fugo; Fugo Takasu, The Joint annual meeting of the Japanese society for mathematical biology and the society for mathematical biology, A spatial modeling of egg mimicry in avian brood parasitism, Aug. 2014, Japanese society for mathematical biology and the society for mathematical biology, 大阪グランキューブ, True
• TAKASU Fugo; Fugo Takasu, The 26th International Ornithological Congress, Modeling the maintenance of egg polymorphism over geographic scale, Aug. 2014, Rikkyo University, Tokyo, True
• TAKASU Fugo; Fugo Takasu, Seminar talk at Jeju National University, Jeju, Korea, Modeling spatial dynamics of egg polymorphism in a cuckoo-host interactions, Jun. 2014, Jeju, Korea, True
• TAKASU Fugo; Fugo Takasu, Seminar talks at Busan National University, Busan, Korea, 1) Spatial population dynamics of "games for territory", 2) Modeling spatial spread of infectious disease - an individual-based approach, 3) Modeling spatial dynamics of egg polymorphism in a cuckoo-host interactions, Jun. 2014, Busan, Korea, True
• TAKASU Fugo; Fugo Takasu, College of Life Sciences, Hainan Normal University, China, Individual-based modeling of the spread of the pine wilt disease, Dec. 2013, True
• TAKASU Fugo; Fugo Takasu, Institute of Forestry and Environmental Sciences, University of Chittagong, Bangladesh, 1) A spatial territory game in continuous space\n2) Individual-based modeling of the spread of pine wilt disease, May 2013, Chittagong, True
• TAKASU Fugo, 日本生態学会第60回全国大会\n企画集会T05「個体の視点から構成する空間個体群動態」, 連続空間上の個体ベース個体群動態, Mar. 2013, 日本生態学会, 静岡県コンベンションセンター（グランシップ）, False
• TAKASU Fugo; Fugo Takasu, International Symposium on Avian Brood Parasitism in Honour of Significant Brood Parasitism Scientists, Modeling maintenance of egg polymorphism over a geographical scale, Nov. 2012, Hainan Normal University, Norwegian University of Science and Technology, and China Ornithological Society, Haikou, Hainan province, China, True
• TAKASU Fugo, 第13回ライチョウ会議岐阜大会, 日本のライチョウ集団のの絶滅可能性解析, Oct. 2012, 高山市役所ホール, False
• TAKASU Fugo; Fugo Takasu; Ayaka Suzuki; nAtsushi Kobayashi; Hiroshi Nakamura, The 12th International Grouse Symposium, An individual-based stochastic population dynamics of the Rock Ptarmigan in Japan, Jul. 2012, Matsumoto, Nagano, Japan, True
• TAKASU Fugo; Fugo Takasu, China-Japan-Korea International Conference of Mathematical Biology, Individual-based models of spatial population/evolutionary dynamics, May 2012, Korean Society of Mathematical Biology, Busan, Korea, True
• TAKASU Fugo, 日本鳥学会員近畿地区懇談会第103回例会, 鳥類育児寄生における卵色多型の集団遺伝モデル, Dec. 2011, 奈良女子大学, False
• TAKASU Fugo, 個体群生態学会 第27回大会（岡山大学 10月14- 16日） 企画シンポジウム「個体ベースで考える集団の争い」, 個体の視点から組み立てる個体群動態モデル, Oct. 2011, 岡山大学, False
• TAKASU Fugo, 第21回日本数理生物学会（明治大学 9月13- 15日）企画シンポジウム「空間的制約下におけるダイナミクス」, 連続空間上の個体ベース個体群動態とその数理的取り扱いについて, Sep. 2011, 明治大学, False
• 高須夫悟, 日本生態学会第69回大会, 力学系モデルから個体ベースモデルを作るやり方, 18 Mar. 2022
• TAKASU Fugo, International Workshop, From behavior to biodiversity linking with population invasion and establishment, Daejeon, Korea, Population invasion models as a point process, 25 Nov. 2021
• TAKASU Fugo, Annual meeting of the Society for Mathematical Biology 2021, Estimation of spatial interaction kernel from time series data - a point pattern approach, 16 Jun. 2021
• TAKASU Fugo; OTA Karan, 個体群生態学会シンポジウム「COVID-19の個体群生態学：疫学と個体群管理の共通点と相違点」, Spatial population dynamics of the pine wilt disease and its application to the disease control, 01 Oct. 2022
• TAKASU Fugo, 数学を用いる生物学：理念・概念と実践・方法論, Pattern dynamics - spatial population dynamics in terms of individuals, 21 Jul. 2022, 20 Jul. 2022, 21 Jul. 2022
• TAKASU Fugo, The Fifth Workshop on Interdisciplinary Sciences (WIS 2023) Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, The method of moments - how individual-based rules of birth, death, and movements of individuals are translated to a dynamical system in spatial ecology, 14 Sep. 2023, 14 Sep. 2023, 15 Sep. 2023

  共同研究・競争的資金等URL
• TAKASU Fugo, 統計思考院人材育成事業ワークショップ 数学を用いる生物学：理念・概念と実践・方法論＠統計数理研究所, Spatial population dynamics as point process, 29 Aug. 2023, 28 Aug. 2023, 29 Aug. 2023

  共同研究・競争的資金等URL
• TAKASU Fugo, The 10th EAFES International Congress, Measuring the degree of egg mimicry in avian brood parasitism - a point pattern approach to quantify egg appearance, 18 Jul. 2023, 17 Jul. 2023, 20 Jul. 2023

  共同研究・競争的資金等URL
• TAKASU Fugo, The 8th CIJK Conference on Mathematical and Theoretical Biology, Spatial population dynamics as point process, 28 Jun. 2023, 27 Jun. 2023, 01 Jul. 2023

  共同研究・競争的資金等URL

Works

• Evolutionary games in continuous space, 2008
• Evolutionary games in continuous space, 2008
• Evolution of competition, Mar. 2005, Dec. 2005
• Evolution of competition, Mar. 2005, Dec. 2005
• Brood parasitism in arctic area, Nov. 2005
• Brood parasitism in arctic area, Nov. 2005
• Avian brood parasitism, Sep. 2005
• Avian brood parasitism, Sep. 2005
• Coevolution of avian brood parasites and their hosts, Jun. 2003, May 2005
• Coevolution of avian brood parasites and their hosts, Jun. 2003, May 2005
• Evolution of host defense in avian brood parasitism, Jan. 2002
• Evolution of host defense in avian brood parasitism, Jan. 2002

Awards

• The Akira Okubo Prize, The Society for Mathematical Biology and the Japanese Society for Mathematical Biology, Jul. 2007
• Ecological Research Award 2007, Ecological Society of Japan, Mar. 2007

Research Projects

• 2022, 2024, 22K06401, Principal investigator
• 01 Apr. 2022, 31 Mar. 2025, 22K06401, Principal investigator
• 2010, 空間個体群動態ならびに空間進化動態, 科学研究費補助金, 0, 0, 0, Competitive research funding
• 2010, Spatial population and evolutionary dynamics, Grant-in-Aid for Scientific Research, 0, 0, 0, Competitive research funding
• 進化動態に関する数理的研究, 0, 0, 0, Competitive research funding
• 動物の分散に関する理論的研究, 0, 0, 0, Competitive research funding
• 鳥類の育児寄生における共進化の理論的研究, 0, 0, 0, Competitive research funding
• Evolurionary dynamics, 0, 0, 0, Competitive research funding
• Theoretical Study on animal dispersal, 0, 0, 0, Competitive research funding
• Theoretical study on avian brood parasitism, 0, 0, 0, Competitive research funding
• Grant-in-Aid for Scientific Research (C), Apr. 2022, Mar. 2025, 22K06401, Principal investigator, Theoretical studies on spatial ecology in terms of point patterns, TAKASU Fugo, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Nara Women's University, 3120000, 2400000, 720000, kaken;rm:published_papers;rm:presentations;rm:presentations;rm:presentations

  対象リソースIRI
• Grant-in-Aid for Scientific Research (B), 2006, 2009, 18405009, Evolutionary arms race between Australian cuckoos and their hosts., UEDA Keisuke; EGUCHI Kazuhiro; BISHIUMI Isao; TAKAGI Masaoki; TAKASU Fugo; HAMAO Shoji, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Rikkyo University, 13190000, 11000000, 2190000, A new anti-parasitism behaviour was observed in the Large-billed Gerygone Gerygone magnirostris and the Mangrove Gerygone G. laevigaster which are hosts of the Little Bronze-cuckoo Chalcites (formally Chrysococcyx) minutillus. This behaviour, termed parasite nestling ejection, involves the physical removal of live parasite nestlings from active nests and represents a type of chick discrimination. The discovery of parasite nestling ejection by Gerygones represented a significant finding for anti-parasitic behaviour research at the nestling stage. Although the Little Bronze-cuckoo seemed to start parasitism to Large-billed Gerygone historically, then they seemed to explore the Mangrove Gerygone as a new host., kaken

  対象リソースIRI
• Grant-in-Aid for Scientific Research (B), 2002, 2005, 14340243, Does the host specific races of the common cuckoo evolve with the gene by the side of female lineages?, NAKAMURA Hiroshi; HAYASHIDA Nobuaki; TAGUCHI Goro; TAKASU Fugo, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Shinshu University, 13300000, 13300000, The common cuckoo is divided into host-specific races (gentes). Females of each race lay a distinctive egg type that tends to match the host's eggs. It was provided genetic evidence that gentes restricted to female lineages from the fact that there is differentiation between gentes in maternally inherited mitochondrial DNA, but not in microsatellite loci of nuclear DNA. This supports recent behavioural evidence that female, but not male, common cuckoos specialize on a particular host, and is consistent with the possibility that genes affecting cuckoo egg type are located on the female-specific W sex chromosome. Our results in Japan also supported these ideas, but the host races are not so clear in Japan, due to colonization by separated ancestral lineages., kaken

  対象リソースIRI
• 若手研究(B), 2002, 2004, 14740421, 群集動態に関する新しい理論アプローチの展開, 高須 夫悟, 日本学術振興会, 科学研究費助成事業, 奈良女子大学, 3400000, 3400000, 平成16年度は主に以下の2点に注目した研究を行った。 1)寄生系におけるパラサイトのハンドリングタイムの進化モデル解析 ホスト・パラサイトの個体群動態において、パラサイトが寄生を実行するに要する時間(ハンドリングタイム)が小さくなると安定平衡点が不安定化し周期解・カオスが出現する事は既に古典モデルの解析に明らかになっている。本研究ではパラサイト集団中にハンドリングタイムに関する集団内変異が存在すると仮定した場合、ハンドリングタイムの進化が個体群動態の安定性に及ぼす影響について解析した。前年度に行った、パラサイトの探索効率の進化モデルと同様、ハンドリングタイムは小さくなる方向へ進化するが、パラサイトのハンドリングタイムに関する集団内変異の存在は、個体群動態をより長期にわたって安定することを見いだした。また、探索効率やハンドリングタイムといった個体群動態に関係するパラメータの進化と個体群動態の安定性に関する一般的な研究を行った。 2)解析的モデルと個体ベースシミュレーションモデルの比較 群集動態や個体群動態の理論研究で用いられる数理モデルの多くは解析的な取り扱いが易い決定論的解析的モデル(差分式、微分方程式等)を用いて記述される。しかし、現実の系では確率論的な効果が無視できず決定論的モデルで起こりうる微小密度下での振る舞いは、必ずしも現実の系を反映していないと思われる。本研究では、決定論的解析モデルで設定される様々な仮定を確率論的ルールに置き換えた確率論的個体ベースモデルを構築し、両者の振る舞いを比べる事で、決定論的解析モデルでは捉えられない現象がある事を見いだした。具体的には、適応度の谷間をすり抜けて形質の進化が起こりうる等である。同様の解析を寄生系の個体群動態モデル及び群集動態モデルに対して行い、確率的な効果の重要性を再認識した。現在はこれを発展させたモデル解析を進めている。, kaken

  対象リソースIRI
• Grant-in-Aid for Scientific Research (C), 2001, 2003, 13640627, Modeling spatio-temporal pattern of biological invasions that involve short-and long-distance dispersals, SHIGESADA Nanako; TAKASU Fugo; KAWASAKI Kohkichi, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Nara Women's University, 2900000, 2900000, The range expansion of an invading species shows a variety of spatio-temporal patterns depending on how the dispersal and reproduction of the organisms take place. To grasp the spatial pattern of invasion and its rate of spread quantitatively, we have constructed two different mathematical models that deal with short-and long-distance dispersals as well as the Allee effect and/or demographic stochasticity : 1)the stratified diffusion model and 2)the integral-kernel-based models. By solving these models either analytically or numerically, we derived formulae for the rate of spread and used them to explore how long-distance dispersal and reproduction interplay to accelerate the speed, or how the Allee effect or demographic stochasticity decelerates it. Integrating the ideas of the above two models together with a cell-automaton model, we carried out simulations for the spread of pine wilt disease in Inbaragi Prefecture, Japan. Pine wilt disease is caused by the pinewood nematode that is vectored by the pine sawyer beetle. The dispersal of the beetle often involves two modes, short-range dispersal and long-range dispersal. We estimated the proportion of long-range dispersers in the population of the disease vector (the pine sawyer beetle) on the basis of field data. Thus we concluded that the dispersal distance of beetles critically affects the expansion speed of the disease, which is sharply amplified, as the fraction of beetles undergoing long distance dispersal increases from zero., kaken

  対象リソースIRI
• 奨励研究(A), 2000, 2001, 12740422, 量的形質に関する共進化の数理的解析, 高須 夫悟, 日本学術振興会, 科学研究費助成事業, 奈良女子大学, 2100000, 2100000, 平成13年度は、昨年度に実施した量的形質に関する共進化モデルの解析をさらに推し進めた。理論解析を進めると同時に、野外での寄生者宿主の関係(カッコウとその宿主)に関するデータを収集し、モデル解析結果と実際の系との比較検討を現在進めている。以下に今年度の研究成果の要点をまとめる。 1)積分差分方程式で記述される本研究のモデルは、遺伝変異が集団内に十分存在すると仮定した場合、従来の量的遺伝モデルとの接点を持つ。しかし、数学的な関連性は未だ不明な点が多く、今後の理論的研究が必要である。また、本研究では卵模様のように量的形質が親から子へそのまま受け継がれる場合を解析したが、有性生殖に一般的な交配による量的形質の変化の効果をモデルに組み込むアイデアをモデル解析の過程で得ることが出来た。現在、その数理的取り扱いについて研究中である。 2)進化一般を議論する新しい理論的枠組みとして、理想自由進化モデルを提唱した。従来の多くのESSモデルの様に集団を一様な「点」として取り扱うのではなく、変異を持った「分布」として取り扱うことで、より柔軟な理論解析が可能になる。 3)托卵鳥系における寄生者と宿主の卵模様(量的形質)の変化を実証することを目指して、2001年6月に琵琶湖にてカッコウの宿主であるオオヨシキリの卵の写真を撮影し、卵模様の画像データを入手した。現在画像データの定量的解析を進めており、共進化の実証を試みている。 4)2年間の研究の取りまとめとして、2001年7月に開催された、数理生物国際会議にて研究発表を行い、内外の研究者と議論を交わした。本研究成果は論文として国際誌に投稿し、査読中である(2001年11月Evolution誌に投稿済み)。 5)寄生系以外の系でも、量的形質を巡る共進化が積分方程式を用いた基本的に同じ枠組みで理論的に取り扱い可能であることを明らかにした。 平成12・13年の2年間で量的形質の共進化に関する理論的研究を大きく推進することが出来た。同時に、今後取り組むべき新たな課題も浮かび上がってきた。この2年間の研究補助をきっかけに、更なる理論的解析を推進していきたい。, kaken

  対象リソースIRI
• Grant-in-Aid for Scientific Research (C), 1998, 2000, 10640616, Mathematical Analyses of Spatial Spread of Pine Wilt Disease, SHIGESADA Nanako; FUGO Takasu; KAWASAKI Kohkichi, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Nara Women's University, 2400000, 2400000, Pine wilt disease is caused by the pinewood nematode, Bursaphelenchus xylophilus, that is vectored by the pine sawyer beetle, Monochamus alternatus. Native Japanese pines, black pine (Pinus thunbergii) and red pine (P.densiflora), are extremely sensitive to the nematode infection and the disease has been expanding nationwide in the last several decades despite intensive control efforts. The dispersal of the beetle often involves two modes, short-range dispersal and long-range dispersal. Short-range dispersal generally occurs through their own active flying, while long-range dispersal is mediated by passive transport on wind or artificial transportation facilities. To evaluate the speed of disease's expansion, we present a model that combines the local dynamics of the pine wilt disease with the dispersal of beetles. Our model predicts several results. (1) The distribution of the dispersal distance of beetles critically affects the expansion speed of the disease. The expansion speed is sharply amplified, as the fraction of beetles undergoing long distance dispersal increases from zero. (2) However, if long range dispersers become too frequent, the disease ceases to expand due to the Allee effect. Thus suggests the importance of correct assessment of the beetle's mobility in predicting the expansion speed of the disease. (3) As the eradication rate is increased, the expansion speed decreases gradually at first and suddenly drops to zero at a certain value of the eradication rate., kaken

  対象リソースIRI
• Grant-in-Aid for Scientific Research (C), 1996, 1997, 08640804, Mathematical Study of Spatial Spread of Biological Invasion, SHIGESADA Nanako; FUGO Takasu; KAWASAKI Kohkichi, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Nara Women's University, 2500000, 2500000, 1. An epidemic of pine wilt disease has been spreading in wide areas of Japan for several decades. The disease is caused by the pinewood nematode, Bursaphelenchus xylophilus, which the pine sawyer, Monochamus alternatus, as vector. We present a mathematical model to describe the host-parasite interaction between pines and pine sawyers carrying nematodes based on detailed data on the population dynamics of pine sawyers and the incidence of pine wilt disease at a study site located on the northwest coast of Japan. By analyzing the model we simulate the temporal change in the incidence of the disease and predict how the epidemic could be controlled by eradication of the pine sawyer. The main results are : 1) There is a minimum threshold of the initial pine density for successful invasion of the disease. However, even if the pine density exceeds the minimum threshold, the disease fails in invasion due to the Allee effect of the pine sawyer when its density is very low. 2) The minimum threshold density increases disproportionately with increase in the eradication rate. 3) The probability for a healthy tree to escape from infection until the epidemic dies out decreases sharply with increase in the initial pine density, when the eradication rate is low. 2. We analyzed the range expansion of an invading species and derived the conditions for persistence of a species two kinds of fragmented environments : (1) an environment segmented into belts, with favorable and unfavorable patches arranged alterately. (2) an environment segmented in both horizontal and vertical axs, with square-shaped favorable patches regularly distributed within the unfavorable environment., kaken

  対象リソースIRI
• 奨励研究(A), 1996, 1996, 08740600, Generalist托卵鳥系における宿主の行動進化の理論的研究, 高須 夫悟, 日本学術振興会, 科学研究費助成事業, 奈良女子大学, 1000000, 1000000, 托卵鳥とその宿主の関係における進化生態学的な問題について数理モデルを用いた研究を行った。托卵されたあるホスト集団は、托卵鳥(パラサイト)の卵を認識して排除する托卵対抗手段をとることが野外研究によって明らかなっているが、托卵対抗手段の確立度はホスト集団ごとに異なっており、この事実に対する明確な説明はなされていなかった。本研究は、托卵鳥が同時に複数の種類のホスト集団に托卵する系(Generalist系)について、托卵対抗手段がそれぞれのホスト集団中でどのように確立されるのかについての数理モデルを組み立て、モデル解析を通じて現実に対する新たな視点を見出すことを目的とした。本研究により明らかになった点は以下の通りである。 1.托卵鳥コウウチョウに托卵されるホストは、托卵対抗手段を殆ど行わないAccepter speciesと、ほぼ完璧な托卵対抗手段をみせるRejecter speciesに分類されることが野外研究から明らかにされているが、このような極端な2分化は、コウウチョウの繁殖戦略-Generalistによって引き起こされている可能性が高い。 2.托卵されながらも托卵対抗手段を行わないAccepter speciesは、対抗手段が突然変異として出現すればRejecter speciesになるという説(Evolutionary Lag説)がある。これに対し、モデル解析から、Accepter speciesの存在は進化的に安定であり、2局化した托卵対抗手段の確立度分布は安定である可能性(Evolutionary Equilibrium説)が示された。この場合、Accepter speciesとRejecter speicesの間には、集団サイズの大きさなどの測定可能な量に違いがあり、これを測定することによって2つの説のどちらがより適切であるかが検討可能である。, kaken

  対象リソースIRI
• Grant-in-Aid for Scientific Research (C), 01 Apr. 2014, 31 Mar. 2017, 26440239, Spatial modeling in ecology as point pattern dynamics, TAKASU Fugo, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Nara Women's University, 4940000, 3800000, 1140000, I have revisited classical spatial population models described such as patch model, lattice model, reaction diffusion model in terms of "point pattern dynamics". These models have been implemented as stochastic point pattern dynamics. I have derived a set of deterministic dynamics of the 1st order (density of points) and the 2nd order (distribution of distances in pair made by two points) which are expected to describe simulations. Triplet density made by thee points appears in the dynamics. With a simple moment closure, the derived deterministic dynamics quite well describes stochastic simulation results, especially when birth and death of points are ignored. I have established the way how classical population dynamics (competition, prey-predator, epidemic models, etc.) can be translated to stochastic point pattern dynamics., kaken;rm:presentations

  対象リソースIRI
• Grant-in-Aid for Scientific Research (A), 01 Apr. 2011, 31 Mar. 2015, 23255004, Evolutionary arms race between tropical cuckoos and their hosts:Exodus from old dogma of western countries., UEDA Keisuke; EGUCHI Kazuhiro; NISHIUMI Isao; TAKASU Fugo; TAKAGI Masaoki; MIKAMI Osamu, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Rikkyo University, 44200000, 34000000, 10200000, We succeeded to reveal the cuckoo-host arms-tace in New Caredonia. We published 3 main papers on the international journal and 12 oral and/or poster papers were presented at several academical societies. Those are often cited by many cuckoo researchers. We also symposium for citizens twice. Many people attended and we have good assessment from them., kaken

  対象リソースIRI
• Grant-in-Aid for Scientific Research (C), 2011, 2013, 23570026, Evolutionary games revisited in terms of individual interactions, TAKASU Fugo, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Nara Women's University, 5330000, 4100000, 1230000, I revisited classical evolutionary games such as Hawk-dove games, Prisoner's dilemma game, evolution of cooperation in terms of individual interactions. Mechanistic interactions among individuals located on a continuous space, not lattice, are algorithmically described and an efficient way to simulate these algorithm of birth, death, and movement, of individuals is implemented by using parallel computing. Population dynamics of each strategy (hawk, dove, defect, cooperate, tit-for-tat, etc.) was analyzed by the singlet density (number of individuals) and the pair density (number of pairs made by two individuals displaced by a certain distance)., kaken

  対象リソースIRI

Ⅲ．社会連携活動実績

１．公的団体の委員等（審議会、国家試験委員、他大学評価委員，科研費審査委員等）

• Ecological Society of Japan, 近畿地区会事務局幹事, 2002, 2003, Society
• 2002, 2003, Society
• Japan Society of Mathematical Biology, 運営委員, Society
• Society
• Ornithological Society of Japan, 英文誌編集委員、広報委員, Society
• Society
• Population Ecology, Editorial Board, Jan. 2012, 9999, Society
• Journal of Ethology, Associate Editor, Jan. 2005, 9999, Society