雌雄异株植物曲尾藓（曲尾藓科）在种群内和种群间的空间遗传结构中，有性和无性繁殖的影响。
The impact of asexual and sexual reproduction in spatial genetic structure within and between populations of the dioecious plant Marchantia inflexa (Marchantiaceae).
机构信息
Department of Biology, University of Kentucky, Lexington, KY, USA.
出版信息
Ann Bot. 2018 Nov 30;122(6):993-1003. doi: 10.1093/aob/mcy106.
BACKGROUND AND AIMS
In dioecious plants, sexual reproduction requires close proximity to potential mates, but clonal growth can increase this distance and, therefore, reduce the probability of mating. Reduction in sexual propagules can lead to decreased dispersal and gene flow between populations. Gene flow and clonal growth may be further influenced by the size of the habitat patch. The effects of habitat size and reproductive mode (sexual or asexual reproduction) on spatial genetic structure and segregation of the sexes were tested by quantifying the distributions of genotypes and the sexes using the dioecious liverwort Marchantia inflexa.
METHODS
Plants were sampled from five pairs of small-large habitat patches to identify within- and among-population spatial genetic structure using 12 microsatellite markers. Spatial distributions were calculated as the likelihood that pairs of individuals were the same sex or genotype, and it was determined how that likelihood was affected by habitat patch size (small/large).
KEY RESULTS
Asexual reproduction dominates within populations, and asexual dispersal also occurred across populations. Spatial segregation of the sexes was observed within populations; males were more likely to be near individuals of the same sex than were females. Although the likelihood of both sexes being near members of the same sex was similarly greater on small habitat patches, on large habitat patches male genotypes were almost 15 % more likely to be near clonemates than were female genotypes.
CONCLUSIONS
The results show a sex difference in clonal clumping that was dependent upon habitat size, suggesting differential colonization and/or survival between males and females. The sexes and genotypes being structured differently within and among populations have implications for the persistence of populations and the interactions between them. This study demonstrates that studying only the sexes and not their genotypes (or vice versa) can limit our understanding of the extent to which reproductive modes (sexual or asexual) influence genetic structure both within and between populations.
背景和目的
在雌雄异株植物中，有性繁殖需要与潜在的配偶近距离接触，但克隆生长会增加这种距离，从而降低交配的可能性。有性繁殖体的减少会导致种群间的扩散和基因流减少。基因流和克隆生长可能会进一步受到栖息地斑块大小的影响。通过量化雌雄同体的基因型和性别分布，检验了栖息地大小和繁殖方式（有性或无性繁殖）对空间遗传结构和性别分离的影响。
方法
从五个小-大栖息地斑块对雌雄同体的肝蕨进行采样，使用 12 个微卫星标记来识别种群内和种群间的空间遗传结构。空间分布被计算为个体对为同一性别或基因型的可能性，并确定栖息地斑块大小（小/大）如何影响这种可能性。
主要结果
无性繁殖在种群内占主导地位，无性扩散也发生在种群之间。在种群内观察到性别空间分离；雄性比雌性更有可能靠近同一性别个体。尽管在小栖息地斑块上，两性都更有可能靠近同一性别成员的可能性相似，但在大栖息地斑块上，雄性基因型比雌性基因型更有可能靠近克隆体，几乎高出 15%。
结论
研究结果表明，在依赖于栖息地大小的情况下，克隆聚集存在性别差异，这表明雌雄个体之间的定植和/或存活存在差异。种群内和种群间存在不同的性别和基因型结构，这对种群的持续存在及其相互作用都有影响。本研究表明，仅研究性别而不研究其基因型（或反之亦然）会限制我们对有性和无性繁殖方式在种群内和种群间影响遗传结构的程度的理解。
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