Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, the Chinese Academy of Sciences, Wuhan, China.
PLoS One. 2012;7(10):e48731. doi: 10.1371/journal.pone.0048731. Epub 2012 Oct 31.
Flowering synchrony and floral sex ratio have the potential to influence the mating opportunities and reproductive success through female function. Here, we examine the variances in synchronous display of female and male function, ratio of male to female flowers per day and subsequently reproductive output in small populations of two monoecious plants, Sagittaria trifolia and Sagittaria graminea.
METHODOLOGY/PRINCIPAL FINDING: We created plant populations of size 2, 4, 10 and 20 and recorded the daily number of blooming male and female flowers per plant to determine daily floral display, flowering synchrony index and ratio of male to female flowers per day. We also harvested the fruits, counted the seeds and calculated the number of fruits and seeds per flower to measure reproductive success through female function. There is less overlap in flowering time of female and male function in smaller populations than in larger populations. Most importantly, we found that male-biased floral sex ratio and imbalanced display period of female and male function for individual plant can lead to a population-size-dependent ratio of male to female flowers per day. Increasing ratio of male to female flowers per day was generally associated with a greater percentage of fruit production.
CONCLUSIONS/SIGNIFICANCE: Our results highlight the importance of flowering synchrony of female and male function and population-size-dependent ratio of male to female flowers per day for female reproductive success. This finding improves our understanding of a mechanism that reduces reproductive success in small populations.
花的同步性和花的性别比例有可能通过雌性功能影响交配机会和繁殖成功率。在这里，我们研究了两个雌雄同体植物，箭叶慈姑和长瓣慈姑的小种群中雌性和雄性功能同步显示、每日雄花与雌花的比例以及随后的繁殖输出的方差。
方法/主要发现：我们创建了大小为 2、4、10 和 20 的植物种群，并记录了每株植物每天开花的雄花和雌花的数量，以确定每日花卉展示、开花同步指数和每日雄花与雌花的比例。我们还收获了果实，数了种子，并计算了每朵花的果实和种子数量，以衡量雌性功能的繁殖成功率。与较大的种群相比，较小种群中雌性和雄性功能的开花时间重叠较少。最重要的是，我们发现个体植物中雄性偏向的花性别比例和雌性和雄性功能展示期的不平衡会导致种群大小依赖的每日雄花与雌花的比例。每日雄花与雌花的比例增加通常与果实产量的百分比增加相关。
结论/意义：我们的研究结果强调了雌性和雄性功能的开花同步性以及每日雄花与雌花的比例对雌性繁殖成功率的重要性。这一发现提高了我们对减少小种群繁殖成功率的机制的理解。
