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Recovery from hybrid breakdown reveals a complex genetic architecture of mitonuclear incompatibilities
Molecular Ecology ( IF 4.9 ) Pub Date : 2021-05-18 , DOI: 10.1111/mec.15985
Ricardo J Pereira 1 , Thiago G Lima 2 , N Tessa Pierce-Ward 2 , Lin Chao 3 , Ronald S Burton 2
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Reproductive isolation is often achieved when genes that are neutral or beneficial in their genomic background become functionally incompatible in a foreign genomic background, causing inviability, sterility or other forms of low fitness in hybrids. Recent studies suggest that mitonuclear interactions are among the initial incompatibilities to evolve at early stages of population divergence across taxa. Yet, the genomic architecture of mitonuclear incompatibilities has rarely been elucidated. We employ an experimental evolution approach starting with low-fitness F2 interpopulation hybrids of the copepod Tigriopus californicus, in which frequencies of compatible and incompatible nuclear alleles change in response to an alternative mitochondrial background. After about nine generations, we observe a generalized increase in population size and in survivorship, suggesting efficiency of selection against maladaptive phenotypes. Whole genome sequencing of evolved populations showed some consistent allele frequency changes across three replicates of each reciprocal cross, but markedly different patterns between mitochondrial backgrounds. In only a few regions (~6.5% of the genome), the same parental allele was overrepresented irrespective of the mitochondrial background. About 33% of the genome showed allele frequency changes consistent with divergent selection, with the location of these genomic regions strongly differing between mitochondrial backgrounds. In 87% and 89% of these genomic regions, the dominant nuclear allele matched the associated mitochondrial background, consistent with mitonuclear co-adaptation. These results suggest that mitonuclear incompatibilities have a complex polygenic architecture that differs between populations, potentially generating genome-wide barriers to gene flow between closely related taxa.

中文翻译:

从杂种分解中恢复揭示了线粒体核不相容性的复杂遗传结构

当基因组背景中性或有益的基因在外来基因组背景中变得功能不相容时,通常会实现生殖隔离,从而导致杂交种不可行、不育或其他形式的低适应性。最近的研究表明,有丝核相互作用是在跨类群种群分化的早期阶段演变的最初不相容性之一。然而,线粒体核不相容性的基因组结构很少被阐明。我们采用了一种实验进化方法,从桡足类Tigriopus californicus的低适应度 F 2种群间杂种开始,其中相容和不相容的核等位基因的频率响应于替代的线粒体背景而变化。大约九代后,我们观察到种群规模和存活率普遍增加,这表明选择针对适应不良表型的效率。进化种群的全基因组测序显示,在每个相互交叉的三个重复中,有一些一致的等位基因频率变化,但线粒体背景之间的模式明显不同。仅在少数区域(约 6.5% 的基因组)中,无论线粒体背景如何,相同的亲本等位基因都被过度表达。大约 33% 的基因组显示出与不同选择一致的等位基因频率变化,这些基因组区域的位置在线粒体背景之间存在很大差异。在这些基因组区域的 87% 和 89% 中,主要的核等位基因与相关的线粒体背景相匹配,这与有丝分裂的共适应一致。这些结果表明,线粒体核不相容性具有复杂的多基因结构,在种群之间存在差异,可能会在密切相关的分类群之间产生全基因组障碍。
更新日期:2021-05-18
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