CANCELLED - Difference in female reproductive success between hermaphrodite and female individuals in a subdioecious shrub plant Eurva japonica Thunb.

Background/Question/Methods Subdioecy is a sexual expression that has female, male, and hermaphroditic individuals in a population. The reason why subdioecious plant species exist is thought to be a reproductive strategy to adapt the growth environment including light and soil condition, resource allocation, the effect of phytophagous insects and pollinators. Therefore, to elucidate the mechanism of a complex sexual expression not only helps to understand abiotic and biotic factors and plant-animal interaction that influence the reproductive success, but also contributes to understand the origin of the sexual expression. Female individuals contribute to the next generation only via seeds, while hermaphrodite individuals produce both seeds and pollens. The difference in resource allocation between hermaphrodite and female individuals might cause the difference in female reproductive success. Therefore, the objectives of this study is to determine and compare female reproductive success (fruit set, seed number, fruit and seed weights, and seed germination rate) between hermaphrodite and female individuals, together with identification of pollinators and existence of resource and pollen limitations, in a subdioecious shrub Eurva japonica.

Results/Conclusions The study was conducted in a secondary forest of Nagoya University, Japan. The main pollinators were gall midges in Cecidomyiidae. The results from control and cross pollination showed that there was pollen limitation in both hermaphrodite and female individuals. On the other hand, we found no significant relationship between light condition (rPPFD) or tree size (D₀) and female reproductive success, indicating that there might be little resource limitation in E. japonica. We also found that the female reproductive success (except for seed weight) of female individuals was significantly higher than that of hermaphrodite individuals. These results suggest that female individuals may have higher advantage of female reproductive success than hermaphrodite individuals because of more attractive traits for pollinators in female flowers.