Genomic differentiation across the speciation continuum in three hummingbird species pairs
Genomic differentiation across the speciation continuum in three hummingbird species pairs
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DOI：
10.1186/s12862-020-01674-9
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发表时间：
2020-09-03
影响因子：
3.4
通讯作者：
Brelsford, Alan
中科院分区：
文献类型：
--
作者：
Henderson, Elisa C.;Brelsford, Alan
随着高分辨率基因组数据的可获得性和可负担性的增加，物种形成的研究已经扩大。基因组如何在分化过程中进化，以及基因组的哪些区域负责引起和维持这种分化一直是最近工作的核心问题。在这里，我们使用三对物种从最近分歧蜜蜂蜂鸟分支调查基因组中的差异在不同阶段的物种形成，使用分歧时间作为代理的物种形成连续体。结果杂交种间相对分化的群体测量表明，不同的染色体类型在不同的物种形成阶段发生分化。使用F（ST）作为我们的分化的相对措施，我们发现，性染色体在物种形成早期显示出分歧的迹象。接下来，小的常染色体（微染色体）积累高度分化的基因组区域，而大的常染色体（大染色体）在物种形成的后期积累分化的基因组区域。结论我们的发现，在小的常染色体上积累的F（ST）升高的基因组窗口早于较大的常染色体上的物种形成，这与F（ST）随染色体大小增加（即重组率降低）的预测相反，并且当每个染色体的加权平均F（ST）与染色体大小相比时，并不代表。本研究的结果表明，重组率和基因密度等多种染色体特征联合收割机会影响分歧特征的基因组位置。
Background The study of speciation has expanded with the increasing availability and affordability of high-resolution genomic data. How the genome evolves throughout the process of divergence and which regions of the genome are responsible for causing and maintaining that divergence have been central questions in recent work. Here, we use three pairs of species from the recently diverged bee hummingbird clade to investigate differences in the genome at different stages of speciation, using divergence times as a proxy for the speciation continuum. Results Population measures of relative differentiation between hybridizing species reveal that different chromosome types diverge at different stages of speciation. Using F(ST)as our relative measure of differentiation we found that the sex chromosome shows signs of divergence early in speciation. Next, small autosomes (microchromosomes) accumulate highly diverged genomic regions, while the large autosomes (macrochromosomes) accumulate genomic regions of divergence at a later stage of speciation. Conclusions Our finding that genomic windows of elevated F(ST)accumulate on small autosomes earlier in speciation than on larger autosomes is counter to the prediction that F(ST)increases with size of chromosome (i.e. with decreased recombination rate), and is not represented when weighted average F(ST)per chromosome is compared with chromosome size. The results of this study suggest that multiple chromosome characteristics such as recombination rate and gene density combine to influence the genomic locations of signatures of divergence.