雌雄异株植物种子性别比例对其种群遗传有重要影响。棋盘模拟模型是推断这类植物种子性别比例非常有力的依据。经该模拟模型推断可得，随着花粉传播距离减少，种子同生群更偏雌性。我们在广东黑石顶保护区多年的野外观察发现：罗浮柿种群繁殖大小年交替进行；由于大年有更多开花雌雄株，其空间间距比小年更小。最近，对保护区内50公顷样地中的所有2271株胸径大于1cm的罗浮柿作性比研究得到：不同径级的亚群体性别比例呈规律地震荡波动；胸径小于2cm的亚群体显著偏雌。据此我们提出假设：罗浮柿在大年，开花的雌雄株彼此空间距离缩小，出现更频繁的短距离传粉事件，导致种子同生群性别比例比小年更偏雌性。本项目拟对样地中罗浮柿繁殖大小年的种子同生群进行调查研究，用分子标记鉴定性别和基因分型，计算大小年种子同生群的性别比例与花粉和种子的平均传播距离，验证假说，检验棋盘模拟模型推断种子性别比例的适用性。

Sex ratio in seeds has profound impacts on population genetics in dioecious plants. The chessboard simulation model provides a useful tool for inferring sex ratio in seeds and predicts that sex ratio in seeds tends to be female-biased with decreasing pollen dispersal distance. We observed an alternate bearing of Diospyros morrisiana in in the Heishiding (HSD) Nature Reserve, Guangdong province, and spatial distance between the flowering male and female individuals significantly decreased in the “on-year” compared to the “off-year”. Recently, we identified sexuality of 2271 individuals of D. morrisiana with diameter at breast height (DBH) ≥1 cm in a 50-ha forest plot in the HSD using a male-linked gene locus (OGI). Our results suggest that the sex ratios of sub-populations with different DBH classes fluctuated regularly and the sub-population with DBH ≤2 cm was significantly female-biased. In this project, we will test the hypothesis that the sex ratio in seeds of D. morrisiana will be more female-baised in the ‘on-year’ compared to the ‘off-year’ due to shorter pollen dispersal distance. To test the hypothesis，we will estimate sex ratios of different seed cohorts and the average pollen dispersal distance and seed dispersal distance in an “on-year” and “off-year”.