高倉 耕一 (タカクラ コウイチ)

TAKAKURA Koichi

写真a

職名

准教授

学内職務経歴 【 表示 / 非表示

  • 滋賀県立大学  環境科学部  生物資源管理学科  准教授   2014年04月 ~ 現在

研究分野(科研費分類) 【 表示 / 非表示

  • 動物生理・行動

  • 生態・環境

  • 生物多様性・分類

  • 生物資源保全学

 

論文 【 表示 / 非表示

  • Comparisons among populations and individuals to evaluate pollen–pistil interaction as a mechanism of reproductive interference in Taraxacum

    Hashimoto K., Yamamoto A., Kanaoka M.M., Naiki A., Takakura K.I., Nishida S.

    Journal of Plant Research  Journal of Plant Research  135 (1)   29 ~ 40  2022年01月

    10.1007/s10265-021-01352-x  共著  

    [概要]

    Reproductive interference (RI), an interspecific mating interaction that reduces the fitness of at least one of the species involved, can lead to exclusive distributions in closely related species. A hypothesis previously proposed is that RI in plants may occur by ovule usurpation, in which pistils lack interspecific incompatibility and mistakenly accept heterospecific pollen, thereby losing an opportunity for conspecific pollen fertilization. However, few comparative studies have evaluated the consistency of the inferred mechanism within and among individuals and populations. We conducted hand-pollination experiments in six populations of three native Taraxacum species that suffered from different levels of RI from an alien congener, T. officinale, and compared pollen–pistil interactions among populations. We also investigated the interactions for eight individual T. japonicum plants whose response to heterospecific pollen deposition had been previously measured. Our results revealed that pollen tubes often penetrated native ovaries following heterospecific pollination in populations suffering from strong RI, whereas they seldom did in populations suffering from marginal RI. However, the relative frequency of the pollen tube penetration was not significantly related to the strength of alien RI. Not all pistils on an individual plant showed the same pollen receptivity following heterospecific pollination; rather, some accepted and some refused the pollen tubes. The relationship between pollen tube penetration following heterospecific pollination and the strength of the alien RI was also not significant among individuals. Our present results generally support the ovule usurpation hypothesis, but suggest that other factors, such as competition for pollinator services, variation in the effects of heterospecific pollen donors, and condition of the native inflorescences, might also affect the observed RI strength.

  • Reproductive habitat use, body-size structure and spawning season of Cobitis minamorii minamorii in paddy fields and ditches

    Morii K., Kitano D., Kanai R., Takakura K.I.

    Ichthyological Research  Ichthyological Research  69 (1)   182 ~ 188  2022年01月

    10.1007/s10228-021-00826-1  共著  

    [概要]

    We surveyed the reproductive ecology of Cobitis minamorii minamorii in paddy fields and ditches. The spatial distribution of females in the spawning season differed from that in the non-spawning season, even in short ditches. Eggs were collected in both ditches and paddy fields, unlike an earlier study demonstrating that no eggs were collected in ditches. The frequency distributions of standard body lengths of males and females were unimodal and bimodal, respectively. The females with a large standard body length were expected to be gravid with higher probability in May.

  • Reproductive behavior of endangered spined loach Cobitis magnostriata in the field

    Morii K., Takakura K.I.

    Journal of Ethology  Journal of Ethology    2022年01月

    10.1007/s10164-022-00746-1  共著  

    [概要]

    Spined loaches, Cobitis spp., have been studied in broad fields of research. Particularly, this taxon has attracted attention because of sexual interactions, such as reproductive interference and hybrid speciation, among species. Nevertheless, knowledge of the reproductive behaviors of this genus has been limited to findings from visual observations of aquarium-resident individuals. For this study, we shot videos and analyzed reproductive behaviors of Cobitis magnostriata in the field. We also investigated cues used by males to track females. Based on our observations conducted at a ditch near the shore of Lake Biwa during May–June, 2020, the sequence of courtship and spawning behaviors was divided into four phases: phase 1, a male tracks a female; phase 2, the male swims parallel to a female; phase 3, the male wraps the posterior part of the female’s body from her dorsal fin and remains motionless; phase 4, after the male wraps the female tighter, the female vibrates to spawn. Additionally, we demonstrated that water vibrations initiate the male tracking behavior (phase 1). The adoption of such a non-species-specific cue might be one reason for which the sexual interspecific interactions have been widely reported in this genus.

  • Differential performance of contrasting defensive traits of cocoons of two moth species against bird predation

    Furukawa M., Nakanishi K., Honma A., Takakura K.I., Matsuyama K., Hidaka N., Sawada H., Nishida T.

    Entomological Science  Entomological Science  24 (3)   261 ~ 269  2021年09月

    10.1111/ens.12482  共著  

    [概要]

    Prey defensive traits against predators can be categorized into primary defense (avoiding detection) and secondary defense (avoiding attack after detection). There are trade-offs between these two defensive traits, which consider the cost of defense. To quantify the predation avoidance efficacy of both defensive traits against common predators, we compared bird predation pressures and the corresponding avoidance measures of cocoons of two nettle moth species, which utilize contrasting avoidance strategies: Parasa lepida (investing predominantly in primary defense) and Monema flavescens (investing predominantly in secondary defense). Field censuses revealed that bird predation was the most significant mortality factor for both species. The survival rate of cocoons was significantly higher for M. flavescens than for P. lepida, although M. flavescens were more conspicuous than P. lepida. Measurement of prepupae (cocoon content) mass, and experiments on the feeding preferences of the prepupae of both species using chicks, confirmed a similar quantity and quality of both speciesʼ prepupae as prey items. Our results were explained by the advantage of cocoon hardness outweighing the disadvantage of cocoon conspicuousness. The predation behavior of wild birds suggested that they spent considerably longer handling than searching for cocoons, which accounted for their cocoon preference for P. lepida over M. flavescens in the context of optimal foraging theory. Our results suggested that secondary defense was more effective in reducing bird predation than primary defense in limacodid cocoons.

  • he striped fruit fly Zeugodacus scutellatus (Diptera: Tephritidae) uses female flowers of Trichosanthes kirilowii var. japonica as host in Shiga Prefecture, Central Japan

    Kitano, D. and K. I. Takakura

     Japanese Journal of Environmental Entomology and Zoology  32   111 ~ 115  2021年

    共著  共同(副担当)

  • Simple and on-site DNA purification for LAMP reaction applicable to non-adult tephritid fruit fly (Diptera: Tephiritidae)

    Kitano D., Takakura K.I.

    Journal of Applied Entomology  Journal of Applied Entomology  144 (9)   824 ~ 829  2020年11月

    10.1111/jen.12820  共著  

    [概要]

    Tephritid fruit flies are important pests of fruits and vegetables worldwide, but few studies have examined their ecology and life history in their native range because non-adult individuals of closely related species are morphologically indistinguishable. To identify non-adult individuals collected from host plants, flies examined in earlier studies were painstakingly reared to adulthood. Using Zeugodacus scutellatus Hendel as a model species, this study established a simple DNA extraction and purification method based on loop-mediated isothermal amplification (LAMP) reaction for on-site molecular identification of non-adult fruit flies. The non-adult individual body fluids were sampled using a sterilized toothpick and then diluted in TE buffer and heated for a short time. Alternatively, eggs were crushed in TE buffer using a sterilized toothpick and then heated. After heated buffer was added to the LAMP reaction mixture as template DNA and the mixture was heated for incubation of polymerase, the LAMP reaction detected the amplified DNA of Z. scutellatus. This purification method, characterized by heating after dilution with TE buffer, is simple and rapid. Our purification method, which obviates large centrifuges, thermal cyclers, and other apparatus, provides lower-cost and better on-site molecular identification of non-adult fruit flies than methods described in earlier reports. The LAMP-based molecular identification technique and our purification method are particularly useful for studying quarantined pest organisms that cannot be removed from their native areas.

  • Habitat partitioning of two closely related pond frogs, Pelophylax nigromaculatus and Pelophylax porosus brevipodus, during their breeding season

    Nakanishi K., Honma A., Furukawa M., Takakura K.I., Fujii N., Morii K., Terasawa Y., Nishida T.

    Evolutionary Ecology  Evolutionary Ecology  34 (5)   855 ~ 866  2020年10月

    10.1007/s10682-020-10061-1  共著  

    [概要]

    Parapatric distributions of closely related species are common in many taxonomic groups. However, habitat overlap in sympatric areas within both species’ ranges is complex and driven by the nature of the interactions between species as well as each species’ ecological requirements. We therefore investigated the distribution of breeding habitats for two congeneric frogs, Pelophylax nigromaculatus and Pelophylax porosus brevipodus, in a region of Japan where these species co-occur, based on observation of mating calls as an index of the abundance of males engaging in reproductive activities. Among a total of 381 surveyed sites, P. nigromaculatus and P. porosus brevipodus were found at 171 and 229 sites, respectively. Pelophylax porosus brevipodus was widely distributed throughout the study area and was more abundant than P. nigromaculatus in sympatric sites. Analysis using cumulative link mixed models revealed that the abundance of calling males was negatively affected by the presence of calling males of the other species and by landscape factors. Interspecific differences in this negative effect appear to favor P. porosus brevipodus over P. nigromaculatus in our study area. Due to differences in the primary habitat preferences of the two species during the non-breeding season, habitat partitioning during the breeding season is likely driven by negative interspecific interactions during the reproductive process (i.e., reproductive interference).

  • Quantitative estimation of reproductive interference between two alien pillbugs introduced into Japan.

    Koh-Ichi Takakura, Teruya Inoue

     Journal of Environmental Entomology and Zoology  31 (2)   43 ~ 50  2020年09月

    共著  共同(主担当)

  • Habitat partitioning in native Geranium species through reproductive interference

    Nishida S., Takakura K.I., Naiki A., Nishida T.

    Annals of botany  Annals of botany  125 (4)   651 ~ 661  2020年03月

    10.1093/aob/mcz210  共著  

    [概要]

    © The Author(s) 2020. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. BACKGROUND AND AIMS: Heterospecific pollen transfer may reduce the fitness of recipient species, a phenomenon known as reproductive interference. A theoretical study has predicted that distributions of species pairs affected by reproductive interference may be syntopic under negligible reproductive interference, sympatric but with partitioning at small spatial scale (i.e. allotopic) under weak interference, or exclusive when reproductive interference is strong. Verifying these predictions is essential for evaluation of the applicability of reproductive interference as a general assembly rule of biological communities. The aim of this study was to test these predictions in two sympatrically distributed wild Geranium species, G. thunbergii and G. wilfordii. METHODS: To measure the effect of reproductive interference, the associations between the relative abundance of the counterpart species and seed set in the focal species, and seed set reduction following mixed pollination, were analysed. The possibility of hybridization with viable offspring was examined by genotyping plants in the field and after mixed pollination. Fertility of putative hybrids was based on their seed set and the proportion of pollen grains with apertural protrusions. A transect study was conducted to examine spatial partitioning, and possible influences of environmental conditions (canopy openness and soil moisture content) on partitioning between the species were analysed. KEY RESULTS: Neither abundance of the counterpart species nor heterospecific pollen deposition significantly affected seed set in the focal species, and hybridization between species was almost symmetrical. Putative hybrids had low fertility. The two species were exclusively distributed at small scale, although environmental conditions were not significantly different between them. CONCLUSIONS: The allotopy of the two species may be maintained by relatively weak reproductive interference through bidirectional hybridization. Re-evaluation of hybridization may allow ongoing or past reproductive interference to be recognized and provide insight into the distributional relationships between the interacting plants.

  • Inhomogeneity of sediment samples in analysis of hexabromocyclododecane

    Ichihara M., Yamamoto A., Kakutani N., Takakura K., Sudo M.

    Environmental Monitoring and Assessment  Environmental Monitoring and Assessment  191 (7)    2019年07月

    10.1007/s10661-019-7553-6  共著  

    [概要]

    © 2019, Springer Nature Switzerland AG. The repeatability test of the analytical method for hexabromocyclododecane (HBCD) was conducted with sediment sample. The maximum HBCD concentration exceeded the minimum by a factor of 90 even though the identical sediment samples were used. Therefore, we examined which step of the analytical method was the factor causing variability. We examined the blank test, and confirmation test of the extraction and purified procedure. From these results, we confirmed that there was nothing wrong with the accuracy of our analytical method. These results indicate that the variability of HBCD concentration in the repeatability test was attributed not to the analytical method, but to the inhomogeneity of the sediment sample. Aluminum, silicon, and organic carbon in sediments were measured to compare the variability of these concentrations with that of HBCD concentration. These concentrations were similar values within identical samples which showed variability in HBCD concentration. HBCD concentration in several samples did not correlate with organic carbon content. These results suggests that sediment samples were homogeneous by itself, and HBCD was heterogeneously distributed in spite of homogeneity of organic carbon in sediment. The sediment sample with variability in HBCD concentration showed different HBCD diastereomer compositions in identical sediment. It implies that the sample contained HBCD derived from different histories or point sources. Even though we increased sample amounts to analyze the homogeneity of the sample, HBCD concentration varied within identical samples if the sample had a hot spot. Past monitoring data may contain overestimation or underestimation of HBCD concentration in sediment.

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研究シーズ 【 表示 / 非表示

  • 生物間相互作用の視点から身近な生物相の成立要因を解き明かす

 

競争的資金(科学研究費補助金・振興調整費・JSPS等) 【 表示 / 非表示

  • シマドジョウ種群の繁殖干渉:農環境の変化による希少種間の同所的繁殖と絶滅リスク

     科学研究費基盤研究(C)   2016年04月 ~ 2019年03月

  • 自家受粉依存性を高める在来種:外来種からの繁殖干渉と遺伝的多様性低下の検証

     科学研究費基盤研究(C)   2013年04月 ~ 2016年03月

 

学部講義等担当 【 表示 / 非表示

  • 動物生態学   2016年04月 ~ 現在

  • 環境フィールドワークⅢ   2015年04月 ~ 現在

  • 生物資源管理学実験Ⅵ   2014年04月 ~ 現在

  • 環境フィールドワークⅡ   2014年04月 ~ 現在