Replicated hybrid zones of Xiphophorus swordtails along an elevational gradient
Replicated hybrid zones of Xiphophorus swordtails along an elevational gradient
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DOI：
10.1111/j.1365-294x.2010.04949.x
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发表时间：
2011-01-01
影响因子：
4.9
通讯作者：
Rosenthal, G. G.
中科院分区：
文献类型：
--
作者：
Culumber, Z. W.;Fisher, H. S.;Rosenthal, G. G.
自然杂交区提供了研究从物种形成到适合度相关性状的遗传基础等一系列进化现象的机会。我们发现，广泛的杂交发生在两个新热带流鱼与部分生殖隔离。系统发育分析表明，剑尾鱼Xiphophorusbirchmanni是单系的，X。malinche是一个独立的单系分支与其他物种的一部分。使用信息的单核苷酸多态性在一个线粒体和三个核内含子位点，我们从23个站点收集的776个样本的基因型沿着7个独立的流到达。混合带在所有河段沿沿着由高到低的梯度重复出现。基因分型显示，地方之间的父母和杂交频率的重大变化。F-IS和连锁不平衡（LD）的测试显示，一般低F-IS和LD，除了在5个群体中，父母种和杂种被发现表明不完全生殖隔离。在这些地点，杂合子缺陷和LD是高的，这表明要么选择对早代杂交或选择性交配。这些数据奠定了基础，以研究复制的混合区结构的适应性基础，并为未来的行为和遗传学的整合，以确定导致在这些混合区观察到的人口遗传模式的过程。
Natural hybrid zones provide opportunities to study a range of evolutionary phenomena from speciation to the genetic basis of fitness-related traits. We show that widespread hybridization has occurred between two neo-tropical stream fishes with partial reproductive isolation. Phylogenetic analyses of mitochondrial sequence data showed that the swordtail fish Xiphophorus birchmanni is monophyletic and that X. malinche is part of an independent monophyletic clade with other species. Using informative single nucleotide polymorphisms in one mitochondrial and three nuclear intron loci, we genotyped 776 specimens collected from twenty-three sites along seven separate stream reaches. Hybrid zones occurred in replicated fashion in all stream reaches along a gradient from high to low elevation. Genotyping revealed substantial variation in parental and hybrid frequencies among localities. Tests of F-IS and linkage disequilibrium (LD) revealed generally low F-IS and LD except in five populations where both parental species and hybrids were found suggesting incomplete reproductive isolation. In these locations, heterozygote deficiency and LD were high, which suggests either selection against early generation hybrids or assortative mating. These data lay the foundation to study the adaptive basis of the replicated hybrid zone structure and for future integration of behaviour and genetics to determine the processes that lead to the population genetic patterns observed in these hybrid zones.