Researchers Database

Ida Takashi

    Faculty Division of Natural Sciences Research Group of Biological Sciences Associate Professor
Last Updated :2021/07/07


Research Areas

  • Natural sciences, Biogeoscience

Research Experience

  • Kyoto University


Published Papers

  • Adaptive significance of light and food for a kleptoplastic sea slug: implications for photosynthesis.

    Hiromi Shiroyama; Sayaka Mitoh; Takashi Y Ida; Yoichi Yusa

    Sacoglossan sea slugs can 'steal' chloroplasts from their algal food and use them for photosynthesis (kleptoplasty). Although it has been shown that light has positive effects on survival and body size retention of some sacoglossans likely through photosynthesis, it is unknown whether light affects their fitness components such as number of offspring or offspring size. Moreover, whether the effects of light extend over the sacoglossans' lifetime has been unexplored. To assess such long-term effects of light intensity and food availability on fitness components, we conducted a 15.9-week laboratory experiment using Elysia atroviridis under a combination of two light intensities (low or high) and two food conditions (with or without food). The total number of eggs laid was greater in the presence of both strong light and food than in other conditions, suggesting positive effects of both light intensity and food availability. The shell height at hatch was also largest in the presence of strong light and food. Larval rearing experiments showed that the size difference at hatch between conditions corresponded to a 1.19-1.93 days growth and 7.9-18.1% survival increase. Thus, positive effects of light and food on the fitness components extend over the lifetime of E. atroviridis., 16 Oct. 2020, Oecologia, True, doi;pubmed

    Scientific journal

  • Multi-cycle synchronous protandry in raceme-like inflorescences of a bumblebee-pollinated herbAconitum grossedentatum

    Takashi Y. Ida; Erina Minato

    Multi-cycle synchronous dichogamy is expected to be a mechanism for reducing self-pollination and sexual interference. It is often found in plants with umbellate inflorescences where pollinator movement is unpredictable, but not in plants with raceme inflorescences that are pollinated by bumblebees. Plants with raceme inflorescences often acropetally open flowers, resulting in an arrangement of females at lower level and males at upper level. This is good enough to preclude geitonogamy because bees tend to move upwardly within the inflorescences. Furthermore, although the degree of segregation of sexes varies among species, their intraspecific variations within a population have rarely been examined. Here, we present a synchronous protandry in bee-pollinatedAconitum grossedentatum, which has a raceme-like inflorescence and opens flowers basipetally. To evaluate the functional significance of synchronous dichogamy in mating, we firstly observed the distribution of sex phases of open flowers. Then, we assessed the effect of each phase flower on foraging behavior by pollinators and seed-set success. The inflorescences tended to exhibit either male- or female-phase flowers at any moment early in the flowering season, but the degree of segregation of sexes declined over time within a population. The degree of the segregation did not affect bumblebee visits to flowers, but it decreased seed-set success of female-phase flowers at that time. Our results demonstrated that synchronous protandry was beneficial for pollination success inA. grossedentatumby avoiding geitonogamy. Nevertheless, we also found asynchronous protandry late in the season, suggesting that the benefits by synchronous protandry decreased over the season., SPRINGER, Oct. 2020, PLANT ECOLOGY, 221 (10), 965 - 978, doi;web_of_science

    Scientific journal

  • Intraspecific neighbourhood effect: Population-level consequence of aggregation of highly defended plants

    Momoka Tamura; Takayuki Ohgushi; Takashi Y. Ida

    There is increasing evidence that herbivore-plant interactions on a focal plant species are influenced by interspecific neighbourhood effects via neighbouring plants (i.e. an associational effect). However, intraspecific neighborhood effects imposed by plant traits have been less appreciated. Specifically, the significance of intraspecific neighbourhood effects in population-level consequences of plants has been totally overlooked. Using two varieties of Nicotiana tabacum (high- and low-nicotine), we evaluated the neighbourhood effects based on patch-level interactions in a split-plot 3 x 3 factorial experiment that manipulated number of plants (4, 9 and 16 plants) and culture type (monoculture plots with high- and low-nicotine plants, and polyculture plot) in an experimental garden. We found that herbivore visits on plants varied depending on the number of plants per patch and culture type. Presence of more high-nicotine plants decreased herbivore visits in the four plant plots, and presence of high-nicotine plants in the nine plant plots decreased herbivore visits on both high- and low-nicotine plants. In contrast, in the 16 plant plots, herbivore visits on high-nicotine plants in polyculture plots were lower than others, including those on high-nicotine plants in monoculture plots. Our findings clearly demonstrated that the intraspecific neighbourhood effect could occur depending on the aggregation of highly defended plants (i.e. high density and/or plant-spacing). This study suggests that multiple mechanisms for the neighbourhood effect simultaneously worked, depending on the patch size and composition of defensive traits of individual plants, and that intraspecific neighbourhood effects may influence population-level consequences for plant-herbivore interaction. A free plain language summary can be found within the Supporting Information of this article., WILEY, Mar. 2020, FUNCTIONAL ECOLOGY, 34 (3), 597 - 605, doi;web_of_science

    Scientific journal

  • Defensive chemicals of neighboring plants limit visits of herbivorous insects: Associational resistance within a plant population

    Takashi Y. Ida; Kojiro Takanashi; Momoka Tamura; Rika Ozawa; Yoshitaka Nakashima; Takayuki Ohgushi

    Despite our understanding of chemical defenses and their consequences for plant performance and herbivores, we know little about whether defensive chemicals in plant tissues, such as alkaloids, and their spatial variation within a population play unappreciated and critical roles in plant-herbivore interactions. Neighboring plants can decrease or increase attractiveness of a plant to herbivores, an example of a neighborhood effect. Chemical defensive traits may contribute to neighborhood effects in plant-herbivore interactions. We examined the effects of nicotine in leaves (a non-emitted defense chemical) on plant-herbivore interactions in a spatial context, using two varieties of Nicotiana tabacum with different nicotine levels. A common garden experiment demonstrated that visits by grasshoppers decreased with increasing density of neighboring plants with a greater nicotine level. In contrast, visits of leaf caterpillars were not affected by neighbors, irrespective of nicotine levels. Thus, our results clearly highlighted that the neighborhood effect caused by the nicotine in leaves depended on the insect identity, and it was mediated by plant-herbivore interactions, rather than plant-plant interactions. This study demonstrates that understanding of effects of plant defensive traits on plant-herbivore interactions requires careful consideration of the spatial distribution of plant defenses, and provides support for the importance of spatial context to accurately capture the ecological and evolutionary consequences of plant-herbivore interactions., WILEY, Dec. 2018, ECOLOGY AND EVOLUTION, 8 (24), 12981 - 12990, doi;web_of_science

    Scientific journal

  • Community-wide impacts of early season herbivory on flower visitors on tall goldenrod

    Mito Ikemoto; Takashi Y. Ida; Shunsuke Utsumi; Takayuki Ohgushi

    1. The flower visitor community consists not only of pollinators but also of non-pollinators, such as florivores, thieves and predators that attack flower visitors. Although there is increasing evidence that early-season foliar herbivory influences pollinator visitation through changes in floral traits, few studies have explored indirect effects of foliar herbivory on community structure of the flower visitors. We examined how early-season foliar herbivory influences the flower visitor community established in late season. 2. We conducted an inoculation experiment using a lacebug (Corythucha marmorata), which is a predominantly herbivorous insect attacking leaves of tall goldenrod (Solidago altissima) in Japan. 3. Flower abundance significantly decreased when damaged by the lacebug. The numbers of pollinators, florivores and thieves were positively correlated with flower abundance, whereas predators were not. In response to flower abundance, florivores decreased on damaged plants. On the other hand, thieves increased on damaged plants, and pollinators and predators did not differ between damaged and undamaged plants. 4. When effects of flower abundance were excluded, foliar herbivory still influenced florivores negatively and thieves positively. This implies that factors besides flower abundance may have affected the numbers of florivores and thieves. 5. Community composition of flower visitors on damaged plants significantly differed from undamaged plants, although overall abundance, taxonomic richness and taxonomic evenness were unaffected by foliar herbivory in the early season. It is important to recognise that only evaluating species diversity and overall abundance may fail to detect the significant consequence of early-season herbivory on the flower visitor community., WILEY, Apr. 2017, ECOLOGICAL ENTOMOLOGY, 42 (2), 164 - 172, doi;web_of_science

    Scientific journal

  • Roles of the seasonal dynamics of ecosystem components in fluctuating indirect interactions on a rocky shore

    Yoko Wada; Keiji Iwasaki; Takashi Y. Ida; Yoichi Yusa

    Accurately evaluating the strengths of direct (i. e., consumptive and non-consumptive) effects and indirect (density-and trait-mediated) interactions is crucial for understanding the mechanisms of the maintenance and dynamics of an ecosystem. However, an in situ evaluation has not been conducted for a long enough period of time to fully consider the seasonality and life histories of the community components. We conducted a 9-month (from summer to spring) field experiment in an intertidal rocky shore ecosystem involving the carnivorous snail, Thais clavigera, its prey, the limpet Siphonaria sirius, and their resources, the cyanobacterium (blue-green alga) Lithoderma sp. and the green algae Ulva spp. From summer to autumn, the predation pressure was high, and the consumptive and non-consumptive effects of the predator had opposite (positive and negative, respectively) effects on the prey. Both the density-and trait-mediated indirect interactions decreased the coverage of Lithoderma and increased the coverage of Ulva. As the predation pressure decreased in autumn, the predator affected both the adults and the new recruits of the prey. The trait-mediated interactions still existed, but the density-mediated interactions were not detected. From winter to spring, no direct effects or indirect interactions were detected because of the low predation pressure. Our investigation highlights previously unnoticed processes-showing that the strengths of the direct effects and indirect interactions fluctuate greatly with the seasonality of the ecosystem components., WILEY, Apr. 2017, ECOLOGY, 98 (4), 1093 - 1103, doi;pubmed;web_of_science

    Scientific journal

  • Field evaluation of synthetic aphid sex pheromone in enhancing suppression of aphid abundance by their natural enemies

    Yoshitaka Nakashima; Takashi Y. Ida; Wilf Powell; John A. Pickett; Michael A. Birkett; Hisatomo Taki; Junji Takabayashi

    The effects of lures containing aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol on abundance of pea aphid, Acyrthosiphon pisum Harris, aphid parasitoids, predators and hyperparasitoids in alfalfa fields were investigated over three years. Although aphid abundance was variable among years, pheromone lure treatment significantly decreased aphid abundance. Among natural enemies of the aphids, only parasitism by the aphid parasitoids Aphidius ervi Haliday and Praon barbatum Mackauer was affected by pheromone lure treatment, with parasitism rates being significantly increased. In contrast, no pheromone lure effects on abundance were detected for predacious species and hyperparasitoids. These results indicate that slow-release formulations of synthetic aphid sex pheromone can attract primary aphid parasitoids and enhance their ability to suppress aphid abundance in the field, and that negative effects on biological control by hyperparasitoids and intraguild predation are not promoted by pheromone lure treatment., SPRINGER, Oct. 2016, BIOCONTROL, 61 (5), 485 - 496, doi;web_of_science

    Scientific journal

  • The consequences of demand-driven seed provisioning for sexual differences in reproductive investment in Thalictrum occidentale (Ranunculaceae)

    Takashi Y. Ida; Lawrence D. Harder; Gaku Kudo

    1. Many iteroparous angiosperms may benefit from flexible annual resource allocation in response to variable reproductive opportunities induced by external conditions. If maximal reproductive investment is fixed, lack of reproductive sinks would cause resource redistribution to other sinks. Alternatively, reproductive investment may vary depending on the demand of reproductive sinks, changing source-sink relations. In particular, differential responses by males and females to the demands of flower and seed production may cause sexual dimorphism. 2. We assess the occurrence of demand-driven seed allocation by females and its implications for sexual differences in reproductive investment, including the dynamics of mass and carbon allocation and the physiological cost of reproduction, for a dioecious, perennial herb, Thalictrum occidentale. We specifically quantified allocation responses to partial defoliation, which reduced current resource supply, and partial flower/fruit removal, which reduced the aggregate demand of reproductive sinks. 3. During flowering, males preferentially invested carbon and mass in flowers at the expense of vegetative organs, whereas females allocated less mass to flowers and invested more in new rhizome production for future performance than males. In contrast, during early fruiting, both sexes had new rhizomes of similar size and a doubling of reproductive mass by females after flowering resulted in similar total reproductive investment for both sexes. Manipulation of the source-sink balance did not influence carbon allocation, except that partial fruit removal increased new rhizome mass compared with intact plants. 4. Females with many fertilized ovules invested proportionally more in seed number and mass per seed than females with few fertilized ovules, indicating both demand-driven seed maturation and its elimination of seed size-number trade-off. Furthermore, males consistently exhibited size-dependent flower production, whereas females exhibited size-dependent flower production only if they had not reproduced during the previous year. 5. Synthesis. This study demonstrates that sexual differences in policies of reproductive investment and the timing of the physiological costs of reproduction impose contrasting allocation schedules. Males invested in reproduction proportionally with their size, whereas females invested flexibly in seeds in response to the demand of developing embryos. Thus, the contrasting certainty and timing of reproductive resource requirements between the sexes contribute to sexual dimorphism., WILEY-BLACKWELL, Jan. 2015, JOURNAL OF ECOLOGY, 103 (1), 269 - 280, doi;web_of_science

    Scientific journal

  • Heating effect by perianth retention on developing achenes and implications for seed production in the alpine herb Ranunculus glacialis

    Takashi Y. Ida; Orjan Totland

    Petals of the alpine, arctic perennial herb Ranunculus glacialis are retained also during seed maturation, as opposed to most species where the petals wither after they have contributed to insect attraction during anthesis. To assess the adaptive significance of perianth retention after anthesis for annual reproduction, we experimentally removed perianths of R. glacialis and explored its impact on achene surface temperature, the growth rate of achenes, carbon allocation, and seed production. Perianth removal immediately after anthesis decreased achene surface temperature, decelerated the growth of achenes and reduced seed set, compared to plants with intact perianth. Measurement of mass allocation showed no further perianth growth during seed maturation, and a C-13 labelling experiment demonstrated that photosynthate allocation to perianths during seed maturation was much smaller than developing achenes. Thus, annual seed production of R. glacialis might be accelerated by perianth retention during seed maturation, while the cost of perianth retention is small compared to that of seed development. In alpine and arctic environments, cold temperatures limit the growth rate of achenes. Hence, the heating of developing achenes by perianth retention might be an adaptive trait that enhances female reproductive success in this arctic, alpine species., SPRINGER BASEL AG, Apr. 2014, ALPINE BOTANY, 124 (1), 37 - 47, doi;web_of_science

    Scientific journal

  • Early onset of spring increases the phenological mismatch between plants and pollinators

    Gaku Kudo; Takashi Y. Ida

    Climate warming accelerates the timing of flowering and insect pollinator emergence, especially in spring. If these phenological shifts progress independently between species, features of plant-pollinator mutualisms may be modified. However, evidence of phenological mismatch in pollination systems is limited. We investigated the phenologies of a spring ephemeral, Corydalis ambigua, and its pollinators (bumble bees), and seed-set success over 10-14 years in three populations. Although both flowering onset and first detection of overwintered queen bees in the C. ambigua populations were closely related to snowmelt time and/or spring temperature, flowering tended to be ahead of first pollinator detection when spring came early, resulting in lower seed production owing to low pollination service. Relationships between flowering onset time, phenological mismatch, and seed-set success strongly suggest that phenological mismatch is a major limiting factor for reproduction of spring ephemerals. This report demonstrates the mechanism of phenological mismatch and its ecological impact on plant-pollinator interactions based on long-term monitoring. Frequent occurrence of mismatch can decrease seed production and may affect the population dynamics of spring ephemerals., ECOLOGICAL SOC AMER, Oct. 2013, ECOLOGY, 94 (10), 2311 - 2320, doi;pubmed;web_of_science

    Scientific journal

  • Photosynthetic compensation by the reproductive structures in the spring ephemeral Gagea lutea

    Ninuola Sunmonu; Takashi Y. Ida; Gaku Kudo

    Growth and reproduction of spring ephemerals inhabiting deciduous forests progress simultaneously during a short period from snowmelt to canopy closure. To clarify the mechanism to mitigate the cost of reproduction, contributions of foliar and non-foliar photosynthetic products to seed production were examined in a spring ephemeral Gagea lutea. Leaf growth, foliar and non-foliar photosynthetic activities, and total assimilated products were compared among reproductive-intact, floral bud-removal, and vegetative plants. Translocation of current photosynthetic products to individual organs was quantified by (CO2)-C-13-trace experiment. Bulb growth was compared between hand-pollination and floral bud-removal treatments. Finally, seed set was compared between intact, leaf-clipping, and bract-clipping treatments. Fruit-forming plants retained leaves longer than vegetative and floral bud-removal plants, but the assimilative contribution of extended leaf longevity was negligible. Carbon supply by bract photosynthesis was large enough for fruit development, while carbon supply by fruit photosynthesis was offset by the high respiration loss. Foliar photosynthetic products were largely transported to bulbs, while translocation to reproductive functions was negligible. Because the floral bud-removal increased the bulb growth, lack of reproduction could lead to more storage. The leaf-clipping had no effect on seed production, while the bract-clipping significantly reduced the seed production. Therefore, current photosynthesis of leafy bracts might be a major carbon source for fruit development. This self-compensative mechanism of reproductive structure enables the continuous reproductive activity in this species., SPRINGER, Feb. 2013, PLANT ECOLOGY, 214 (2), 175 - 188, doi;web_of_science

    Scientific journal

  • Demand-driven resource investment in annual seed production by a perennial angiosperm precludes resource limitation

    Takashi Y. Ida; Lawrence D. Harder; Gaku Kudo

    The limits on annual seed production have long been characterized as restriction by either pollination success or resource provision to seed development. This expected dichotomy between pollen and resource limitation is based on the assumption that reproductive resources are fixed, which is reasonable for semelparous species. In contrast, iteroparity can ease the constraints on reproductive output per breeding season, if resources can be either mobilized from past storage or borrowed against future performance. For perennial plants, these options allow enhanced reproductive investment in response to unusually good pollination, so that annual seed production may not be pollen or resource limited. We assessed demand-governed reproductive investment by manipulating both resource supply capacity (partial defoliation) and resource demand (pollination quality: fully self-pollination, fully cross-pollination, or combinations of partial self-and cross-pollination within the inflorescence) for a forest herb, Stenanthium occidentale, which is subject to strong pre-dispersal inbreeding depression. Insensitivity to partial defoliation indicated that reproductive output was not source regulated. Instead, demand by developing seeds governs resource distribution, as demonstrated by elevated photosynthate translocation to fruits on fully cross-pollinated plants and the ability of completely defoliated plants to produce seeds. Such contingent resource allocation eliminates a simple dichotomy between pollen receipt and resource availability as limits on annual seed production. Instead, such flexible reproductive investment allows iteroparous perennials to participate maximally in current reproduction (as determined by ovule production) following superior pollination, or to conserve resources for future reproduction following poor pollination., ECOLOGICAL SOC AMER, Jan. 2013, ECOLOGY, 94 (1), 51 - 61, doi;pubmed;web_of_science

    Scientific journal

  • Effects of defoliation and shading on the physiological cost of reproduction in silky locoweed Oxytropis sericea

    Takashi Y. Ida; Lawrence D. Harder; Gaku Kudo

    Background The production of flowers, fruits and seeds demands considerable energy and nutrients, which can limit the allocation of these resources to other plant functions and, thereby, influence survival and future reproduction. The magnitude of the physiological costs of reproduction depends on both the factors limiting seed production (pollen, ovules or resources) and the capacity of plants to compensate for high resource demand. Methods To assess the magnitude and consequences of reproductive costs, we used shading and defoliation to reduce photosynthate production by fully pollinated plants of a perennial legume, Oxytropis sericea (Fabaceae), and examined the resulting impact on photosynthate allocation, and nectar, fruit and seed production. Key Results Although these leaf manipulations reduced photosynthesis and nectar production, they did not alter photosynthate allocation, as revealed by (13)C tracing, or fruit or seed production. That photosynthate allocation to reproductive organs increased >190% and taproot mass declined by 29% between flowering and fruiting indicates that reproduction was physiologically costly. Conclusions The insensitivity of fruit and seed production to leaf manipulation is consistent with either compensatory mobilization of stored resources or ovule limitation. Seed production differed considerably between the two years of the study in association with contrasting precipitation prior to flowering, perhaps reflecting contrasting limits on reproductive performance., OXFORD UNIV PRESS, Jan. 2012, ANNALS OF BOTANY, 109 (1), 237 - 246, doi;pubmed;web_of_science

    Scientific journal

  • Seasonal patterns of carbon assimilation and allocation of a summer-green forest herb, Parasenecio auriculata (Senecioneae; Asteraceae)

    Takashi Y. Ida; Gaku Kudo

    Summer-green herbs inhabiting deciduous forests often put out aerial shoots under bright conditions before tree-canopy closure and grow until late summer under the closed canopy. Some of them produce leaves continuously even after the initiation of canopy closure, indicating an exploitation of the low light period. The manner of carbon assimilation during bright and shade periods within a growth season should reflect the seasonal patterns of vegetative growth and reproductive allocation of individual species. We examined the seasonal patterns of assimilation, partitioning of photosynthate between reproduction and storage, and the budget of reproduction of a perennial understory herb, Parasenecio auriculata. Although photosynthetic rates per unit leaf area decreased with the seasonal reduction in light level, net assimilation at the whole-plant level was maintained at a high level even after canopy closure owing to the increase in the total leaf area. Stored resource in tubers contributed to the rapid development of aerial shoots in the early season, and annual tuber growth was completed before flowering. Instant photosynthetic products considerably contributed to the maintenance of flowers but not to fruit development because of low assimilation rate during fruiting. These findings indicated that carbon assimilation during flowering contributes to sexual reproduction without influencing the development of storage organs. Stable carbon assimilation over summer by shade-acclimatized leaves enabled the maintenance of high productivity associated with high sexual reproduction., SPRINGER, Sep. 2010, PLANT ECOLOGY, 210 (1), 181 - 193, doi;web_of_science

    Scientific journal

  • Modification of bumblebee behavior by floral color change and implications for pollen transfer in Weigela middendorffiana

    Takashi Y. Ida; Gaku Kudo

    Flowers of Weigela middendorffiana change the color from yellow to red. The previous study revealed that red-phase flowers no longer have sexual function and nectar, and bumblebees selectively visit yellow-phase flowers. The present study examined how retaining color-changed flowers can regulate the foraging behavior of bumblebees and pollen transport among flowers within (geitonogamous pollination) and between (outcrossing pollination) plants and how the behavior is influenced by display size (i.e., number of functional flowers) and visitation frequency. The visitation frequencies of bumblebees to plants and successive flower probes within plants were observed in the field using plants whose flower number and composition of the two color-phase flowers had been manipulated. To evaluate pollination efficiency over multiple pollinator visits, a pollen transport model was constructed based on the observed bumblebee behavior. In the simulation, three flowering patterns associated with display size and existence of color-changed flowers were postulated as follows: Type 1, large display (100 functional flowers) and no retention of color-changed flowers; Type 2, small display (50 functional flowers) and retention of color-changed flowers (50 old flowers), and; Type 3, large display (100 functional flowers) and retention of color-changed flowers (100 old flowers). Color-changed flowers did not contribute to increasing bumblebee attraction at a distance but reduced the number of successive flower probes within plants. Comparisons of pollen transfer between Types 1 and 3 revealed that the retention of color-changed flowers did not influence the total amount of pollen exported when pollinator visits were abundant (> 100 visits) but decreased geitonogamous pollination. Comparisons between Types 2 and 3 revealed that the discouragement effect of floral color change on successive probes accelerated in plants with a large display size. Overall, the floral color change strategy contributed to reduce geitonogamous pollination, but its effectiveness was highly sensitive to display size and pollinator frequency., SPRINGER, Jul. 2010, EVOLUTIONARY ECOLOGY, 24 (4), 671 - 684, doi;web_of_science

    Scientific journal

  • Carbon source for reproduction in a spring ephemeral herb, Corydalis ambigua (Papaveraceae)

    Gaku Kudo; Takashi Y. Ida

    P>1. The carbon source for reproduction in plants may differ between flowering and fruiting stages. To clarify how spring ephemerals use current photosynthetic products for reproduction, the allocation patterns of photosynthate at flowering and fruiting and the effects of resource limitation on reproductive performance in Corydalis ambigua were assessed. 2. A 13C tracing experiment revealed that about 20% of the current photosynthetic carbon was used for reproduction at both flowering and fruiting. The proportion of 13C allocated to fruits was constant irrespective of the light level. In contrast, 13C translocation to tubers increased at fruiting, and this trend was accelerated when plants were shaded. 3. Defoliation treatment significantly reduced nectar production and tuber mass, while seed production was not affected. Therefore, when carbon assimilation was limited, carbon was preferentially allocated to current reproduction (seeds) rather than to pollinator attraction (nectar) or storage (tuber). 4. If seed production is partly supported by carbohydrate reserved in the old tissue of tubers, nectar and seed production may not compete strongly for carbon sources. In contrast to the ability of high seed production, the susceptibility of nectar production to current photosynthesis indicates that seed production of this species is basically limited by pollen capture. 5. Therefore, temporal separation of resource pool for reproduction may mitigate the joint limitation of seed production between pollinator attraction and resource availability. Temporal variation of the sink-source balance of storage organ is crucial to understand the cost of reproduction in perennial plants., WILEY-BLACKWELL PUBLISHING, INC, Feb. 2010, FUNCTIONAL ECOLOGY, 24 (1), 62 - 69, doi;web_of_science

    Scientific journal

  • Comparison of light harvesting and resource allocation strategies between two rhizomatous herbaceous species inhabiting deciduous forests

    Takashi Y. Ida; Gaku Kudo

    Light conditions on the floor of deciduous forests are determined by the leaf dynamics of canopy trees and gap formation. Such spatiotemporal variations of light availability should affect the resource partitioning strategies of understory herbs. Although rhizomatous species are common in understory, relationships between rhizome structure, vegetative growth, and sexual reproduction are unclear in terms of carbon allocation. We compared the photosynthetic characteristics and carbon translocation patterns in the under-canopy and light-gap sites between two summer-green perennial species: Cardamine leucantha with an annual long rhizome, and Smilacina japonica with a perennial short rhizome system. Flowering of both species occurs in early summer under decreasing light availability. In the light-gap, C. leucantha maintained high photosynthetic activity due to continuous leaf production, resulting in higher seed production than in the under-canopy. In contrast, the photosynthetic rate of S. japonica, producing leaves simultaneously, decreased with time irrespective of light conditions, resulting in stable seed production in both sites. Although seasonally decreasing light availability commonly restricts carbon assimilation of understory herbs, the responses of resource partitioning to variations in light availability depend greatly on the belowground structure of individual species., SPRINGER TOKYO, Mar. 2009, JOURNAL OF PLANT RESEARCH, 122 (2), 171 - 181, doi;pubmed;web_of_science

    Scientific journal

  • Timing of canopy closure influences carbon translocation and seed production of an understorey herb, Trillium apetalon (Trilliaceae)

    Takashi Y. Ida; Gaku Kudo

    Background and Aims The light availability on a temperate, deciduous-forest floor varies greatly, reflecting the seasonal leaf dynamics of the canopy trees. The growth and/or reproductive activity of understorey plants should be influenced by the length of the high-irradiance period from snowmelt to canopy closure. The aim of the present study was to clarify how spring-blooming species regulate the translocation of photosynthetic products to current reproduction and storage organs during a growing season in accordance with the changing light conditions. Methods Growth pattern, net photosynthetic rate, seed production, and shoot and flower production in the next year of Trillium apetalon were compared between natural and experimentally shaded conditions. Furthermore, translocation of current photosynthetic products within plants was assessed by a labelled carbon-chase experiment. Key Results During the high-irradiance period, plants showed high photosynthetic ability, in which current products were initially used for shoot growth, then reserved in the rhizome. Carbon translocation to developing fruit occurred after canopy closure, but this was very small due to low photosynthetic rates under the darker conditions. The shading treatment in the early season advanced the time of carbon translocation to fruit, but reduced seed production in the current year and flower production of the next year. Conclusions Carbon translocation to the storage organ had priority over seed production under high-irradiance conditions. A shortened bright period due to early canopy closure effectively restricts carbon assimilation, which greatly reduces subsequent reproductive output owing to low photosynthetic products for fruit development and small carbon storage for future reproduction. As populations of this species are maintained by seedling recruitment, acceleration of canopy closure timing may influence the maintenance and dynamics of populations., OXFORD UNIV PRESS, Feb. 2008, ANNALS OF BOTANY, 101 (3), 435 - 446, doi;pubmed;web_of_science

    Scientific journal

  • Linkages between phenology, pollination, photosynthesis, and reproduction in deciduous forest understory plants

    Gaku Kudo; Takashi Y. Ida; Tomokazu Tani

    Light availability in the understory of deciduous forests changes drastically within the growing season due to the foliage dynamics of canopy trees. Because flowering phenology, photosynthetic characteristics, and fruiting success respond to such strong seasonality in light availability, we hypothesized that understory plants in such ecosystems should describe distinct phenological groups or syndromes where "syndrome'' is defined only as a set of characteristics that co-occur. To identify these phenological syndromes, we studied the flowering phenology, fruit or seed set, and photosynthetic characteristics for 18 perennial understory herbaceous species that differed in reproductive strategy over eight years in a deciduous forest in northern Japan. Three phenological groups emerged from this study: (1) spring bloomers, flowering and fruiting before the completion of canopy closure; (2) early-summer bloomers, flowering during the progress of canopy closure and fruiting after canopy closure; and (3) late-summer bloomers, flowering and fruiting after canopy closure. The spring bloomers had high photosynthetic rates and high fruiting abilities, but the flowering time varied considerably among years due to yearly fluctuations of snowmelt date. Bumble bee-pollinated species of spring bloomers showed variable seed-set success, while fly-pollinated species showed relatively stable seed sets over the years. The early-summer bloomers showed low fruiting abilities irrespective of pollination success, reflecting severe resource limitation with decelerating light availability during fruit development. Although the late-summer bloomers showed low photosynthetic rates under low-light conditions, high fruit-set success was attained if pollination was sufficient. These results support our hypothesis that phenological syndromes may be found in deciduous forest understory plants. Given that reproductive success of bee-pollinated spring bloomers is highly susceptible to seasonal fluctuation, climate change may have its strongest impacts on this group., ECOLOGICAL SOC AMER, Feb. 2008, ECOLOGY, 89 (2), 321 - 331, doi;pubmed;web_of_science

    Scientific journal

  • Floral sex allocation in a hermaphrodite herb with 1-day flowers, Hosta rectifolia (Liliaceae)

    Guo-Xing Cao; Gaku Kudo; Takashi Y. Ida

    The size-dependent sex allocation theory predicts that a female-based sex allocation is accelerated with increasing resource status in insect-pollinated hermaphrodite plants. However, variations in the mating environment among flowers, which are caused by pollinator movements and temporal fluctuation in the floral sex ratio, may cause diverse patterns in sex allocation among flowers within inflorescences. We examined the floral sex allocation among plants and among flowers within inflorescences in a perennial hermaphrodite species with 1-day flowers, Hosta rectifolia Nakai. Flowering progresses sequentially from basal to distal positions within an inflorescence with little flowering overlap among flowers. At the plant level, both pollen and ovule production per flower increased with plant size. Within inflorescences, both ovule and pollen production per flower declined from basal to distal positions, indicating decreasing resource availability per flower. The probability of fruit-set success under natural conditions also decreased from basal to distal positioned flowers within inflorescences. However, the pollen to ovule ratio of individual flowers remained constant, regardless of floral position and plant size. Constant sex allocation at the flower level is consistent with the prediction of the mating environment theory; every positioned flower seemed to have a similar potential of pollination success because there was no geitonogamous pollination., BLACKWELL PUBLISHING, Dec. 2007, PLANT SPECIES BIOLOGY, 22 (3), 191 - 196, doi;web_of_science

    Scientific journal

  • A test of the effect of floral color change on pollination effectiveness using artificial inflorescences visited by bumblebees

    Gaku Kudo; Hiroshi S. Ishii; Yuimi Hirabayashi; Takashi Y. Ida

    Floral color change has been recognized as a pollination strategy, but its relative effectiveness has been evaluated insufficiently with respect to other floral traits. In this study, effects of floral color change on the visitation pattern of bumblebees were empirically assessed using artificial flowers. Four inflorescence types were postulated as strategies of flowering behavior: type 1 has no retention of old flowers, resulting in a small display size; type 2 retains old flowers without nectar production; type 3 retains old flowers with nectar; and type 4 retains color-changed old flowers without nectar. Effects of these treatments varied depending on both the total display size (single versus multiple inflorescences) and the pattern of flower-opening. In the single inflorescence experiment, a large floral display due to the retention of old flowers (types 2-4) enhanced pollinator attraction, and the number of flower visits per stay decreased with color change (type 4), suggesting a decrease in geitonogamous pollination. Type-4 plants also reduced the foraging time of bees in comparison with type-2 plants. In the multiple inflorescence experiment, the retention of old flowers did not contribute to pollinator attraction. When flowering occurred sequentially within inflorescences, type-4 plants successfully decreased the number of visits and the foraging time in comparison with type-2 plants. In contrast, floral color change did not influence the number of visits, and it extended the foraging time when flowering occurred simultaneously within inflorescences but the opening of inflorescences progressed sequentially within a plant. Therefore, the effectiveness of floral color change is highly susceptible to the display size and flowering pattern within plants, and this may limit the versatility of the color change strategy in nature., SPRINGER, Nov. 2007, OECOLOGIA, 154 (1), 119 - 128, doi;pubmed;web_of_science

    Scientific journal

  • Floral color change in Weigela middendorffiana (Caprifoliaceae): reduction of geitonogamous pollination by bumble bees

    TY Ida; G Kudo

    We examined the significance of retaining color-changed flowers in pollination success of Weigela middendorffiana through a single visit of bumble bees. Inner parts of flowers changed color with age from yellow to red. In an investigation of the mating system, duration of each color phase, reproductive ability of each of the color-phase flowers, and the effects of color-changed flowers on bumble bee behavior (1) flowers of this species were self-incompatible, (2) color-changed flowers provided little reward to pollinators and little residual reproductive ability, (3) the timing of floral color change was delayed with the progress of flowering season within individual plants, while the duration of the red phase shortened with the progress of flowering season, and (4) red-phase flowers did not attract bumble bees at a distance but did contribute to reducing the number of successive flower visits during a single stay within the plants. Red-phase flowers seemed to indicate the low reward level of old flowers and functioned as a cue to discourage pollinators from staying longer on the same plant. Our results predict that the retention of color-changed flowers without sexual function can enhance the pollination success of a whole plant through male function by reducing successive flower visits during a single stay of pollinators, i.e., geitonogamous pollination., BOTANICAL SOC AMER INC, Dec. 2003, AMERICAN JOURNAL OF BOTANY, 90 (12), 1751 - 1757, doi;pubmed;web_of_science

    Scientific journal


  • Ecological significance of floral color change

    井田 崇

    日本生物科学者協会, Apr. 2009, Biological science, 60 (3), 151 - 158, cinii_articles

Association Memberships

  • Canadian Society for Ecology and Evolution

  • 日本生態学会

  • 種生物学会

  • 日本植物学会

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