Department of Genetics, Institute of Experimental Biology, Kazimierz Wielki University, 85064 Bydgoszcz, Poland.
Ann Bot. 2013 Aug;112(3):561-74. doi: 10.1093/aob/mct131. Epub 2013 Jun 19.
Sexual reproduction is one of the most important moments in a life cycle, determining the genetic composition of individual offspring. Controlled pollination experiments often show high variation in the mating system at the individual level, suggesting a persistence of individual variation in natural populations. Individual variation in mating patterns may have significant adaptive implications for a population and for the entire species. Nevertheless, field data rarely address individual differences in mating patterns, focusing rather on averages. This study aimed to quantify individual variation in the different components of mating patterns.
Microsatellite data were used from 421 adult trees and 1911 seeds, structured in 72 half-sib families collected in a single mixed stand of Quercus robur and Q. petraea in northern Poland. Using a Bayesian approach, mating patterns were investigated, taking into account pollen dispersal, male fecundity, possible hybridization and heterogeneity in immigrant pollen pools.
Pollen dispersal followed a heavy-tailed distribution (283 m on average). In spite of high pollen mobility, immigrant pollen pools showed strong genetic structuring among mothers. At the individual level, immigrant pollen pools showed highly variable divergence rates, revealing that sources of immigrant pollen can vary greatly among particular trees. Within the stand, the distribution of male fecundity appeared highly skewed, with a small number of dominant males, resulting in a ratio of census to effective density of pollen donors of 5·3. Male fecundity was not correlated with tree diameter but showed strong cline-like spatial variation. This pattern can be attributed to environmental variation. Quercus petraea revealed a greater preference (74 %) towards intraspecific mating than Q. robur (36 %), although mating preferences varied among trees.
Mating patterns can reveal great variation among individuals, even within a single even-age stand. The results show that trees can mate assortatively, with little respect for spatial proximity. Such selective mating may be a result of variable combining compatibility among trees due to genetic and/or environmental factors.
有性繁殖是生命周期中最重要的时刻之一，决定了个体后代的遗传组成。受控授粉实验经常显示个体水平交配系统的高度变异性，表明自然种群中个体变异的持续存在。交配模式的个体变异可能对种群和整个物种具有重要的适应性意义。然而，实地数据很少涉及交配模式的个体差异，而是侧重于平均值。本研究旨在量化交配模式不同组成部分的个体变异。
使用来自波兰北部一个混合的欧洲山毛榉和欧洲栓皮栎林分中 421 棵成年树和 1911 颗种子的微卫星数据，这些数据构成了 72 个半同胞家系。使用贝叶斯方法，考虑到花粉传播、雄性繁殖力、可能的杂交和异质的外来花粉库，研究了交配模式。
花粉传播遵循长尾分布（平均 283 米）。尽管花粉迁移率很高，但外来花粉库在母树之间表现出强烈的遗传结构。在个体水平上，外来花粉库的分化速率差异很大，表明特定树木的外来花粉源可能有很大差异。在林分内，雄性繁殖力的分布呈高度偏态分布，少数优势雄性导致普查到的花粉供体与有效密度之比为 5.3。雄性繁殖力与树径无关，但表现出强烈的类峰度空间变异。这种模式可归因于环境变化。欧洲栓皮栎比欧洲山毛榉（74%对 36%）表现出更强的种内交配偏好，尽管交配偏好因树木而异。
交配模式可以揭示个体之间的巨大差异，即使在单个同龄林分内也是如此。结果表明，树木可以进行选择性交配，很少考虑空间接近度。这种选择性交配可能是由于树木之间遗传和/或环境因素导致的可变结合相容性的结果。
