Shuhei Matsuyama | Rakuno Gakuen University (original) (raw)
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Papers by Shuhei Matsuyama
Sexual dimorphisms are often found in reproductive allocation and vegetative growth, and these se... more Sexual dimorphisms are often found in reproductive allocation and vegetative growth, and these sexual dimor-phisms may lead to a reduction of subsequent reproductive allocation in woody dioecious species. However, in some species , female-biased reproductive allocation does not result in a reduction of subsequent reproductive allocation in females. To clarify the mechanisms underlying this phenomenon, we studied the dioecious tree Zanthoxylum ailanthoides Sieb. et Zucc., in which leafing and inflorescence development occur sequentially. Reproductive allocation and vegetative growth were examined in both sexes at the shoot and tree levels. At tree level, they were evaluated with respect to flowering frequency and annual tree-ring width over 5 years. Reproductive allocation per shoot in females was 1.7Â that in males. The ratio of reproductive to total current-year shoots per tree in males was 1.2Â that in females. Reproductive allocation in females exceeded that of males by a factor of 1.5 at the tree level, which was less than that at the shoot level, owing to modular integrity. Biased vegetative growth was not detected at the leaf, shoot, or tree level, suggesting that a compensatory mechanism is not employed by this species. The results support the conclusion that a species-specific phenophase sequence of Z. ailanthoides enables females to achieve consecutive reproductive allocation.
We examined the floral display size and potential pollinators of female and male Rhus trichocarpa... more We examined the floral display size and potential pollinators of female and male Rhus trichocarpa in northern Kyoto, Japan, in June 2005. The entomophilous pollination system comprised 431 insects and one spider belonging to 124 species. Most pollinators were non-social bees and occasional Diptera and Coleoptera, whereas eusocial bees were not dominant in the pollination system. Male-biased frequencies were observed in the eusocial bees and in some of the non-social bees, probably because they are sensitive to the larger male floral rewards. A pollinator introduction experiment confirmed that malebiased, unbiased and infrequent non-social bees can pollinate R. trichocarpa, indicating that non-social bees can contribute to fruit set. The results suggest that there are likely to be two different functional groups of generalist pollinators: (i) the majority of the pollinators may contribute to reproductive success through unbiased and occasional visits; and (ii) a minority group of eusocial bees may contribute to reproductive success through male-biased visits.
Sexual dimorphisms are often found in reproductive allocation and vegetative growth, and these se... more Sexual dimorphisms are often found in reproductive allocation and vegetative growth, and these sexual dimor-phisms may lead to a reduction of subsequent reproductive allocation in woody dioecious species. However, in some species , female-biased reproductive allocation does not result in a reduction of subsequent reproductive allocation in females. To clarify the mechanisms underlying this phenomenon, we studied the dioecious tree Zanthoxylum ailanthoides Sieb. et Zucc., in which leafing and inflorescence development occur sequentially. Reproductive allocation and vegetative growth were examined in both sexes at the shoot and tree levels. At tree level, they were evaluated with respect to flowering frequency and annual tree-ring width over 5 years. Reproductive allocation per shoot in females was 1.7Â that in males. The ratio of reproductive to total current-year shoots per tree in males was 1.2Â that in females. Reproductive allocation in females exceeded that of males by a factor of 1.5 at the tree level, which was less than that at the shoot level, owing to modular integrity. Biased vegetative growth was not detected at the leaf, shoot, or tree level, suggesting that a compensatory mechanism is not employed by this species. The results support the conclusion that a species-specific phenophase sequence of Z. ailanthoides enables females to achieve consecutive reproductive allocation.
We examined the floral display size and potential pollinators of female and male Rhus trichocarpa... more We examined the floral display size and potential pollinators of female and male Rhus trichocarpa in northern Kyoto, Japan, in June 2005. The entomophilous pollination system comprised 431 insects and one spider belonging to 124 species. Most pollinators were non-social bees and occasional Diptera and Coleoptera, whereas eusocial bees were not dominant in the pollination system. Male-biased frequencies were observed in the eusocial bees and in some of the non-social bees, probably because they are sensitive to the larger male floral rewards. A pollinator introduction experiment confirmed that malebiased, unbiased and infrequent non-social bees can pollinate R. trichocarpa, indicating that non-social bees can contribute to fruit set. The results suggest that there are likely to be two different functional groups of generalist pollinators: (i) the majority of the pollinators may contribute to reproductive success through unbiased and occasional visits; and (ii) a minority group of eusocial bees may contribute to reproductive success through male-biased visits.