Incomplete reproductive isolation and low genetic differentiation despite floral divergence across varying geographic scales in Castilleja
Incomplete reproductive isolation and low genetic differentiation despite floral divergence across varying geographic scales in Castilleja
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DOI：
10.1002/ajb2.1700
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发表时间：
2021-07-21
影响因子：
3
通讯作者：
Skogen，Krissa A.
中科院分区：
文献类型：
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作者：
Wenzell，Katherine E.;McDonnell，Angela J.;Skogen，Krissa A.
优势分化取决于选择的强度和分类群间基因流动的频率，而生殖隔离取决于交配障碍和地理距离。关于这些过程在物种形成的早期阶段是如何相互作用的，人们知之甚少。在此，我们比较了最近分化的卡斯蒂利亚属在花型和遗传序列水平上的分化，以探索不同生殖隔离情景下的多样性模式。方法利用被子植物353探针组启动的靶浓缩，我们估计了4个卡斯蒂利亚属50个居群的遗传距离。我们调查了在两个焦点群中，遗传分化模式是否由花性状变异或地理距离来解释：广谱C。无菌花和限制较多的C。结果我们记录了这一点。Sessiliflora和C.紫色复合体的特点是在不同的地理范围内花卉颜色高度多样化。尽管在表型上存在差异，但群体在系统发育分析中没有得到很好的支持，并且在目标被子植物353个基因座上几乎没有发现遗传分化。尽管如此，单核苷酸多态的主坐标分析显示了inC基因的分化。无菌花在花型和地理分布上均有差异，且种间分化较小。结论遗传距离公司的模式。尽管花的性状不同，但在很长的距离内仍保持着最高的物种凝聚力。在C区。紫色复合体，在狭窄的地理斜坡之间的花色差异可能是由最近对花色的选择所驱动的。这些花卉和遗传分化的对比模式表明，分化可以通过多种生态进化途径产生。
PremiseDivergence depends on the strength of selection and frequency of gene flow between taxa, while reproductive isolation relies on mating barriers and geographic distance. Less is known about how these processes interact at early stages of speciation. Here, we compared population‐level differentiation in floral phenotype and genetic sequence variation among recently divergedCastillejato explore patterns of diversification under different scenarios of reproductive isolation.MethodsUsing target enrichment enabled by the Angiosperms353 probe set, we assessed genetic distance among 50 populations of fourCastillejaspecies. We investigated whether patterns of genetic divergence are explained by floral trait variation or geographic distance in two focal groups: the widespreadC. sessilifloraand the more restrictedC. purpureaspecies complex.ResultsWe document thatC. sessilifloraand theC. purpureacomplex are characterized by high diversity in floral color across varying geographic scales. Despite phenotypic divergence, groups were not well supported in phylogenetic analyses, and little genetic differentiation was found across targeted Angiosperms353 loci. Nonetheless, a principal coordinate analysis of single nucleotide polymorphisms revealed differentiation withinC. sessilifloraacross floral morphs and geography and less differentiation among species of theC. purpureacomplex.ConclusionsPatterns of genetic distance inC. sessiliflorasuggest species cohesion maintained over long distances despite variation in floral traits. In theC. purpureacomplex, divergence in floral color across narrow geographic clines may be driven by recent selection on floral color. These contrasting patterns of floral and genetic differentiation reveal that divergence can arise via multiple eco‐evolutionary paths.