Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas, Apdo. 1056, E-41080 Sevilla, Spain.
Am J Bot. 2005 Aug;92(8):1264-9. doi: 10.3732/ajb.92.8.1264.
Gynodioecy is a dimorphic breeding system in which hermaphrodite and female individuals coexist in populations. Sex ratio and gender-relative lifetime seed production determine the stability of gynodioecy, and both genetic and ecological factors may influence these parameters. I analyzed the consequences of variation in population sex ratio and site elevation for the relative pollination success of female and hermaphrodite individuals of Daphne laureola in southern Spain, where previous studies failed to detect female fecundity advantages at two mid-elevation sites. Pollination success, estimated as stigmatic pollen loads, number of pollen tubes per style, and percentage of fertilized flowers, was higher for hermaphrodites than females in populations with 20-56% females. Furthermore, female quantitative disadvantage in pollination success increased with elevation, suggesting that the higher availability of pollen due to the increased proportion of hermaphrodites could not mitigate the negative effect that other factors associated with elevation apparently had on pollination. Supplemental hand pollinations showed that female seed production was pollen limited in populations with a proportion of females >50%, although both pollination success and natural fruit set of females in these sites were the highest recorded.
雌雄异熟是一种两性异形的繁殖系统，其中雌雄同体和雌性个体在种群中共存。性别比例和性别相对终生种子产量决定了雌雄异熟的稳定性，遗传和生态因素都可能影响这些参数。我分析了种群性别比例和地点海拔的变化对西班牙南部 Daphne laureola 中雌性和雌雄同体个体相对授粉成功率的影响，此前的研究未能在两个中海拔地点检测到雌性繁殖力优势。授粉成功率，估计为柱头花粉负荷、花柱内花粉管数量和受精花朵的百分比，在 20-56%的雌性个体的种群中，雌雄同体高于雌性个体。此外，随着海拔的升高，雌性在授粉成功率方面的定量劣势也随之增加，这表明由于雌雄同体比例增加而导致的花粉可用性增加，无法减轻与海拔相关的其他因素对授粉的负面影响。补充人工授粉表明，在雌性比例>50%的种群中，雌性种子产量受到花粉限制，尽管这些地点的授粉成功率和自然结实率都是记录到的最高值。
