Limited pollen dispersal, small genetic neighborhoods, and biparental inbreeding in Vallisneria americana Michx. (Hydrocharitaceae)

Premise of the study: Pollen dispersal is a key process that influences ecological and evolutionary dynamics of plant populations by facilitating sexual reproduction and gene flow. Habitat loss and fragmentation have the potential to reduce pollen dispersal within and among habitat patches. We assessed aquatic pollen dispersal and mating system characteristics in Vallisneria americana -- a water-pollinated plant with a distribution that has been reduced from historic levels. Methods: We examined pollen neighborhood size, biparental inbreeding, and pollen dispersal, based on seed paternity using the indirect paternity method KinDist, from samples of 18 - 39 mothers and 14 - 20 progeny per mother from 3 sites across 2 years. Key Results: On average, fruits contained seeds sired by 7 fathers. We found significant biparental inbreeding and limited pollen dispersal distances (0.8 - 4.34 m). However, in a number of cases correlated paternity did not decline with distance and dispersal could n...

研究背景：花粉扩散是通过促进有性生殖与基因流，进而影响植物种群生态与进化动态的关键过程。栖息地丧失与生境破碎化可能会降低生境斑块内部及斑块间的花粉扩散水平。本研究针对美洲苦草（Vallisneria americana）——一种分布范围较历史水平有所缩减的水媒传粉植物——评估其水生花粉扩散与交配系统特征。
研究方法：本研究基于种子父本信息，采用间接父本分析方法（indirect paternity method）KinDist，对2年间3个采样位点的18至39株母本以及每株母本对应的14至20株子代样本进行分析，以此探究花粉邻域大小、双亲近交及花粉扩散情况。
主要研究结果：平均而言，每个果实内的种子由7个父本完成授粉。本研究发现了显著的双亲近交现象，且花粉扩散距离受限（0.8~4.34米）。然而在部分案例中，相关父本比例并未随距离增加而降低，且扩散可能...