Data from: Genetic structure of a naturally regenerating post-fire seedling population: Pinus halepensis as a case study

To study the effects of wildfire on population genetics of a wind pollinated and wind dispersed tree, we have analyzed the genetic structure of a post-fire, naturally regenerating seedling population of Pinus halepensis Miller, on Mt. Carmel, Israel. We tested the existence of spatial genetic structure, which is expected due to the special spatial demographic structure of the post-fire seedling and sapling populations of this species. Explicitly, we asked whether or not seedlings that germinated under large, burned, dead pine trees are also their offspring. The results revealed that the post-fire seedling population is polymorphic, diverse, and reflects the pre-fire random mating system. In contrast to our prediction, we found no division of the post-fire seedling population to distinct sub-populations. Furthermore, as a result of post-fire seed dispersal to longer range than the average pre-fire inter-tree distance, seedlings found under individual burned trees were not necessarily their sole offspring. Although the population as a whole showed a Hardy-Weinberg equilibrium, significant excess of heterozygotes was found within each tallest seedlings group growing under single, large, burned pine trees. Our finding indicates the possible existence of intense natural selection for the most vigorous heterozygous genotypes that are best adapted to the special post-fire regeneration niche, which is the thick ash bed under large, dead, pine trees.

为探究野火对风媒传粉、风播树木种群遗传学的影响，我们对以色列卡梅尔山（Mt. Carmel）地区一处火灾后自然更新的阿勒颇松（Pinus halepensis Miller）幼苗种群的遗传结构展开了分析。鉴于该物种种火后幼苗及幼树种群具备独特的空间种群统计结构，我们检验了本应存在的空间遗传结构是否确实存在。具体而言，我们探究了在大型过火枯松树下萌发的幼苗是否即为该母树的后代。研究结果显示，该火后幼苗种群具备多态性与遗传多样性，且契合火灾前的随机交配体系。与我们的预测相悖的是，我们并未发现火后幼苗种群分化为显著的亚种群。此外，由于火后种子传播距离相较于火灾前树木间的平均距离有所增加，单株过火树下的幼苗未必仅为该母树的后代。尽管该种群整体符合哈迪-温伯格平衡（Hardy-Weinberg equilibrium），但在单株大型过火松树下生长的各组最高幼苗中，均检测到杂合子显著过量的现象。我们的研究结果表明，可能存在针对最具活力的杂合基因型的强烈自然选择——这类基因型最适配大型枯松树下厚积灰烬这一特殊的火后更新生态位。