TAKAKURA Koichi

写真a

Title

Associate Professor

Campus Career 【 display / non-display

  • University of Shiga Prefecture  School of Environmental Science  Department of Biological Resources Management  Associate Professor   2014.04 - Now

 

Papers 【 display / non-display

  • Reproductive interference between two serious pests, oriental fruit flies Bactrocera carambolae and B. dorsalis (Diptera: Tephritidae), with very wide but partially overlapping host ranges

    Kitano D., Fujii N., Sujiono, Yamaue S., Kitamura T., Honma A., Tsukada M., Nishida T., Sawada H., Takakura K.

    Applied Entomology and Zoology  Applied Entomology and Zoology  53 (4)   525 - 533  2018.11

    10.1007/s13355-018-0584-6  Joint Work  

    [Abstract]

    © 2018, The Japanese Society of Applied Entomology and Zoology. Bactrocera carambolae and B. dorsalis (Diptera: Tephritidae) are extremely destructive pests of fruits and vegetables in the Asia-Pacific region. Earlier reports have described that B. carambolae and B. dorsalis, respectively, use mainly star fruit and mango, suggesting a certain level of host partitioning which can be ascribed neither to differences in larval food qualities nor host-specific parasitoid mortality. This study specifically examined reproductive interference (antagonistic sexual interaction) between B. carambolae and B. dorsalis as a potential factor strongly affecting their host partitioning. We observed mating behaviors, especially interspecific courtships and mating, by cohabiting the conspecific and heterospecific pairs together. Consequently, we quantified their effects on the reproductive success of females. Males of both species frequently courted their own females, but they also courted females of other species. Courtship refusal by females was not selective in males of either species. This incomplete discrimination of both sexes led to frequent occurrences of interspecific sexual interactions in both species, but only B. carambolae females showed reduced reproductive success. These results suggest that B. dorsalis, superior in reproductive interference, can occupy high-quality mango, whereas B. carambolae, inferior in reproductive interference, must use low-quality star fruit.

  • Does simultaneous and sympatric reproduction between two native spined loaches lead to reproductive interference and local extinction?

    Morii K., Nakano M., Takakura K.

    Environmental Biology of Fishes  Environmental Biology of Fishes  101 (9)   1407 - 1416  2018.09

    10.1007/s10641-018-0787-2  Joint Work  

    [Abstract]

    © 2018, Springer Nature B.V. Reproductive interference occurs when fitness of females of one species decreases because of misdirected courtship behaviors by males of another species. Reproductive interference strongly excludes either species in the interaction but it does not persist for long on an evolutionary time scale. Therefore, reproductive interference between a pair of co-evolved native species is difficult to observe because exclusion ends the interaction even if even the potential for reproductive interference still exists. However, anthropogenic environmental changes can bring about secondary contact between two species and trigger reproductive interference, leading to local species extinction. We demonstrated this phenomenon with two native spined loaches: Cobitis magnostriata (Cmag) and C. minamorii oumiensis (Cmio). In 2015 and 2016, we investigated the spatiotemporal dynamics of adults and juveniles of both species to estimate the effects of the relative abundance of adults on reproductive success. Additionally, we surveyed the distribution of juveniles and investigated the proportion of gravid females which failed to reproduce at the end of the spawning season. In 2016, Cmio juveniles were fewer than in 2015, although the abundances of Cmio adults were similarly low in both years and the Cmag adults were more abundant in 2016 than in 2015. The juveniles of the two species exhibited similar spatiotemporal dynamics. At the end of the spawning season, Cmag males were abundant and most Cmio females failed to reproduce. These results suggest that the two species share spawning habitats and seasons and that Cmag males exert reproductive interference on Cmio females. This report is the first of a study suggesting that anthropogenic environmental changes triggered reproductive interference between native species in the field.

  • Skewed male reproductive success and pollen transfer in a small fragmented population of the heterodichogamous tree Machilus thunbergii

    Watanabe S., Takakura K., Kaneko Y., Noma N., Nishida T.

    Journal of Plant Research  Journal of Plant Research  131 (4)   623 - 631  2018.07

    10.1007/s10265-018-1018-9  Joint Work  

    [Abstract]

    © 2018, The Botanical Society of Japan and Springer Japan KK, part of Springer Nature. Heterodichogamy is defined as the presence of two flower morphs that exhibit the male and female functions at different times among individuals within a population. Heterodichogamy is regarded as an adaptation to promote outcrossing through enhanced inter-morph mating, together with a 1:1 morph ratio. However, in highly fragmented populations, the morph ratio may be more likely to be biased by stochastic events. In such a situation, individuals of a minority morph within a population are expected to have higher reproductive success than those of a majority morph, which may suffer from pollen shortages of the minority morph. In this paper, we evaluated mating patterns and male reproductive success in a highly fragmented population of Machilus thunbergii, a putative heterodichogamous evergreen laurel tree. Results of paternity analysis indicated that the selfing rate was not clearly different between the two morphs. In contrast, the proportion of intra-morph mating was higher in the majority-morph (MM) mother trees than in the minority-morph (MF) mother trees. Bayesian estimated male reproductive success indicated that male reproductive success was higher in minority-morph (MF) than in majority-morph (MM) mother trees. These findings indicate that (1) the majority morph mothers, suffering a shortage of the opposite morph pollen, could partly compensate for the reduced reproductive success by intra-morph mating rather than by selfing, and (2) negative-frequency dependent selection may be involved in the maintenance of the two morphs.

  • Growth patterns of juveniles observed at a shared spawning site in two closely related species of spined loaches endemic to the Lake Biwa riverine system; Cobitis magnostriata and C. minamorii oumiensis

    Morii K,Nakano M, Nishida T, Takakura KI

     Japanese Journal of Environmental Entomology and Zoology    2018

    Joint Work  Joint(The vice charge)

  • Age class structure of spawning populations of two endangered endemic striated spined loaches in Lake Biwa river system.

    Morii K, Takakura KI

     Japanese Journal of Environmental Entomology and Zoology  29   135 - 141  2018

    Single Work  Joint(The vice charge)

  • A Bayesian approach for estimating hexabromocyclododecane (HBCD) diastereomer compositions in water using data below limit of quantification

    Ichihara M., A. Yamamoto, M. Sudo, K.I. Takakura

     Environmental Science and Pollution Research  24 (3)   2667 - 2674  2017

    Joint Work  Joint(The vice charge)

  • Skewed male reproductive success and pollen transfer in a small fragmented population of the heterodichogamous tree Machilus thunbergii.

    Shuntaro Watanabe, Koh‑Ichi Takakura, Yuko Kaneko, Naohiko Noma, Takayoshi Nishida

     Journal of Plant Research    2017

    Joint Work  Joint(The vice charge)

  • Estimation of population size of an endangered plant, Arabidopsis kamchatica ssp. kawasakiana

    Aya Kozugi, Koh-Ichi Takakura, Naohiko Noma, Akira Kawabe, Emiko Harada

     Bulletin of Kansai Organization for Nature Conservation  38 (1)   51 - 59  2016.06

    Joint Work  Joint(The vice charge)

  • A comparison of host utilization between sibling fruit flies Bactrocera carambolae and B. papayae (Diptera: Tephritidae) in west Java, Indonesia, serious quarantine pest of fruits

     Japanese Journal of Environmental Entomology and Zoology  26 (4)   133 - 141  2016.01

    Joint Work  Joint(The vice charge)

  • Spatial distribution of flower color induced by interspecific sexual interaction

    Takahashi Y., K. Takakura and M. Kawata

     PLoS ONE  11   e0164381 -  2016

    10.1371/journal.pone.0164381  Joint Work  Joint(The vice charge)

display all >>

Conferences 【 display / non-display

  • Island biogeography of invasive vs. native plants, The 31st Annual Meeting of the Society of Population Ecology

    第31回個体群生態学会  2015.10