Allopatric divergence and secondary contact with gene flow: a recurring theme in rattlesnake speciation
Allopatric divergence and secondary contact with gene flow: a recurring theme in rattlesnake speciation
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DOI：
10.1093/biolinnean/blz077
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发表时间：
2019-06
影响因子：
1.9
通讯作者：
Drew R. Schield;B. W. Perry;Richard H. Adams;D. Card;Tereza Jezkova;G. M. Pasquesi;Zachary L. Nikolakis;Kristopher W. Row;J. Meik;Cara F. Smith;S. Mackessy;T. Castoe
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文献类型：
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作者：
Drew R. Schield;B. W. Perry;Richard H. Adams;D. Card;Tereza Jezkova;G. M. Pasquesi;Zachary L. Nikolakis;Kristopher W. Row;J. Meik;Cara F. Smith;S. Mackessy;T. Castoe
对地理范围相接触的最近分化的谱系的研究可以深入了解物种形成的早期阶段以及生殖隔离在产生和维持物种中的潜在作用。这种洞察力也可以是重要的理解的战略和挑战，界定物种在最近分化的物种复合体。在这里，我们使用线粒体和核遗传数据来研究人口结构，基因流和人口历史在地理上广泛分布的响尾蛇分支，西部响尾蛇物种复杂（Crotalus cerberus，Crotalus viridis，Crotalus oreganus和亲戚），其中包含多个谱系，范围在地理上重叠或相互接触。我们发现的证据表明，这一组的进化历史不符合分叉树模型和普遍的基因流广泛影响了当今的遗传多样性模式。我们的研究结果表明，谱系多样性已形成主要是由漂移和分歧的选择隔离，其次是二次接触，生殖隔离机制显得薄弱，不足以防止基因渗入，即使在古代分歧的谱系。分歧的复杂性和与谱系之间的基因流的二次接触也提供了新的背景，为什么在这个复杂的范围内划分物种在历史上一直是困难和有争议的。
The study of recently diverged lineages whose geographical ranges come into contact can provide insight into the early stages of speciation and the potential roles of reproductive isolation in generating and maintaining species. Such insight can also be important for understanding the strategies and challenges for delimiting species within recently diverged species complexes. Here, we use mitochondrial and nuclear genetic data to study population structure, gene flow and demographic history across a geographically widespread rattlesnake clade, the western rattlesnake species complex (Crotalus cerberus, Crotalus viridis, Crotalus oreganus and relatives), which contains multiple lineages with ranges that overlap geographically or contact one another. We find evidence that the evolutionary history of this group does not conform to a bifurcating tree model and that pervasive gene flow has broadly influenced patterns of present-day genetic diversity. Our results suggest that lineage diversity has been shaped largely by drift and divergent selection in isolation, followed by secondary contact, in which reproductive isolating mechanisms appear weak and insufficient to prevent introgression, even between anciently diverged lineages. The complexity of divergence and secondary contact with gene flow among lineages also provides new context for why delimiting species within this complex has been difficult and contentious historically.