Comparative linkage mapping uncovers recombination suppression across massive chromosomal inversions associated with local adaptation in Atlantic silversides
Comparative linkage mapping uncovers recombination suppression across massive chromosomal inversions associated with local adaptation in Atlantic silversides
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DOI：
10.1111/mec.16472
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发表时间：
2022-04-24
影响因子：
4.9
通讯作者：
Therkildsen, Nina O.
中科院分区：
文献类型：
--
作者：
Akopyan, Maria;Tigano, Anna;Therkildsen, Nina O.
重组在基因组进化中的作用早已在理论上进行了研究，但直到最近，实证研究还局限于少数模式物种。在这里，我们比较了大西洋银鱼（Menidia Menidia）两个种群的重组景观和基因组共线性，这是一种分布在北美大西洋海岸陡峭的纬度气候梯度上的小鱼。我们为来自纽约和乔治亚州的本地适应种群及其种群间实验室杂交构建了单独的连锁图谱。首先，我们使用其中一个连锁图谱，通过将三个大的未放置支架固定在两条染色体上，来改善当前的银侧基因组组装。其次，我们估计了性别特异性重组率，发现雌性的重组率比雄性高2.3倍——这是鱼类中异交最极端的例子之一。虽然重组在女性染色体中相对均匀地发生，但它仅限于男性染色体的末端。此外，对女性连锁图谱的比较显示，沿着几个巨大的染色体倒位抑制重组，跨越近16%的基因组。这些倒置在适应当地环境的种群之间是分离的，并且与野生种群之间高度升高的基因组分化几乎完全吻合。最后，我们发现北方种群的染色体重组率明显高于南方种群。除了为正在进行的进化和比较基因组研究提供宝贵的资源外，我们的研究结果还代表了结构变异影响适应性不同种群之间重组的显著例子，为促进基因流动的适应性的理论基因组机制提供了经验支持。
The role of recombination in genome evolution has long been studied in theory, but until recently empirical investigations had been limited to a small number of model species. Here, we compare the recombination landscape and genome collinearity between two populations of the Atlantic silverside (Menidia menidia), a small fish distributed across the steep latitudinal climate gradient of the North American Atlantic coast. We constructed separate linkage maps for locally adapted populations from New York and Georgia and their interpopulation laboratory cross. First, we used one of the linkage maps to improve the current silverside genome assembly by anchoring three large unplaced scaffolds to two chromosomes. Second, we estimated sex-specific recombination rates, finding 2.3-fold higher recombination rates in females than males-one of the most extreme examples of heterochiasmy in a fish. While recombination occurs relatively evenly across female chromosomes, it is restricted to only the terminal ends of male chromosomes. Furthermore, comparisons of female linkage maps revealed suppressed recombination along several massive chromosomal inversions spanning nearly 16% of the genome. These inversions segregate between locally adapted populations and coincide near perfectly with blocks of highly elevated genomic differentiation between wild populations. Finally, we discerned significantly higher recombination rates across chromosomes in the northern population compared to the southern. In addition to providing valuable resources for ongoing evolutionary and comparative genomic studies, our findings represent a striking example of structural variation that impacts recombination between adaptively divergent populations, providing empirical support for theorized genomic mechanisms facilitating adaptation despite gene flow.