Abstract

Habitat fragmentation strongly affects the genetic diversity of plant populations, and this has always attracted much research interest. Although numerous studies have investigated the effects of habitat fragmentation on the genetic diversity of plant populations, fewer studies have compared species with contrasting breeding systems while accounting for phylogenetic distance. Here, we compare the levels of genetic diversity and differentiation within and among subpopulations in metapopulations (at fine-scale level) of two closely related Zingiber species, selfing Zingiber corallinum and outcrossing Zingiber nudicarpum. Comparisons of the genetic structure of species from unrelated taxa may be confounded by the effects of correlated ecological traits or/and phylogeny. Thus, we possibly reveal the differences in genetic diversity and spatial distribution of genetic variation within metapopulations that relate to mating systems. Compared to outcrossing Z. nudicarpum, the subpopulation genetic diversity in selfing Z. corallinum was significantly lower, but the metapopulation genetic diversity was not different. Most genetic variation resided among subpopulations in selfing Z. corallinum metapopulations, while a significant portion of variation resided either within or among subpopulations in outcrossing Z. nudicarpum, depending on whether the degree of subpopulation isolation surpasses the dispersal ability of pollen and seed. A stronger spatial genetic structure appeared within subpopulations of selfing Z. corallinum potentially due to restricted pollen flow and seed dispersal. In contrast, a weaker genetic structure was apparent in subpopulations of outcrossing Z. nudicarpum most likely caused by extensive pollen movement. Our study shows that high genetic variation can be maintained within metapopulations of selfing Zingiber species, due to increased genetic differentiation intensified primarily by the stochastic force of genetic drift among subpopulations. Therefore, maintenance of natural variability among subpopulations in fragmented areas is key to conserve the full range of genetic diversity of selfing Zingiber species. For outcrossing Zingiber species, maintenance of large populations is an important factor to enhance genetic diversity.Compared to outcrossing Z. nudicarpum, the subpopulation genetic diversity in selfing Z. corallinum was significantly lower, but the metapopulation genetic diversity did not differ. Most genetic variation resided among subpopulations in selfing Z. corallinum metapopulations, while a significant portion of variation resided either within or among subpopulations in outcrossing Z. nudicarpum, depending on whether the degree of subpopulation isolation surpasses the dispersal ability of pollen and seed. Our study shows that selfing Z. corallinum could maintain high genetic diversity through differentiation intensified primarily by the stochastic force of genetic drift among subpopulations at fine-scale level, but not local adaptation.

中文翻译：

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两种密切相关的自交和异交的Zingiber物种（Zingiberaceae）的种群内的遗传变异和遗传结构

摘要

栖息地碎片化强烈影响植物种群的遗传多样性，这一直吸引着许多研究兴趣。尽管许多研究调查了生境破碎化对植物种群遗传多样性的影响，但很少有研究将物种与对比育种系统进行比较，同时考虑了系统发生距离。在这里，我们比较了两个紧密相关的Zingiber物种，自交Zingiber珊瑚和自交Zingiber的Nindcarpum的亚种群（细规模水平）的亚种群内和亚种群之间的遗传多样性和分化水平。。来自不相关的分类单元的物种的遗传结构的比较可能会因相关的生态性状或/和系统发育的影响而混淆。因此，我们可能揭示与交配系统有关的种群中遗传多样性和遗传变异空间分布的差异。与异形Z相比。nudicarpum，在自交子群的遗传多样性ž。Corallinum显着降低，但其种群遗传多样性没有差异。大多数遗传变异都位于自交Z的亚种群之间。珊瑚群体，而变异的很大一部分位于异交Z的亚群体之内或之中。裸核果，取决于亚群分离的程度是否超过花粉和种子的分散能力。自交Z的亚群内出现了较强的空间遗传结构。可能由于花粉流动受限和种子扩散而导致的珊瑚。相反，在异型Z的亚群中遗传结构较弱。莲carp很可能是花粉大量运动引起的。我们的研究表明，在自交姜的自交群中可以保持较高的遗传变异物种，由于增加的遗传分化，主要是由于亚群之间遗传漂移的随机作用而加剧的。因此，维持零散区域中亚种群之间自然变异性是保护自交姜类物种完整遗传多样性的关键。对于异交姜种，大量人口的维护是提高遗传diversity.Compared异型杂交的一个重要因素Z. nudicarpum，在自交子群的遗传多样性Z. corallinum是显著回落，但集合种群的遗传多样性没有差异。大多数遗传变异都存在于自交Z. Corallinum的亚种群中种群，而变异的很大一部分驻留在异交Z. nudicarpum的亚种群内部或之中，这取决于亚种群分离的程度是否超过花粉和种子的分散能力。我们的研究表明，自交的Z. Corallinum可以通过分化而维持较高的遗传多样性，而分化主要是由细种群水平的亚种群间遗传漂移的随机力增强的，而不是局部适应的。