Reproductive isolation in a three-way contact zone
Reproductive isolation in a three-way contact zone
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DOI：
10.1111/mec.17275
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发表时间：
2024-01-18
影响因子：
4.9
通讯作者：
MacColl，Andrew D. C.
中科院分区：
文献类型：
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作者：
Dean，Laura L.;Whiting，James R.;MacColl，Andrew D. C.
一个物种内不同形式之间的接触区提供了对基因流在适应和物种形成中的作用的深入了解。以前的工作集中在接触区，只涉及两种不同的形式，但在自然界中，两个以上的人口可能同时重叠，并经历基因流。因此，野生种群中的基因渗入模式可能比通常假设的要复杂得多。我们开始，以解决目前的知识差距，通过调查模式的分歧和渗入整个复杂的自然接触区。我们使用表型和基因组数据来确认苏格兰西部岛屿北尤斯特岛上不同的淡水居民，咸水居民和咸水迁移三棘鱼（Gasterosteus aculeatus）之间存在三方接触区。我们发现杂交的证据，主要是咸水居民和咸水迁移形式之间。尽管杂交，基因组分析揭示了所有形式之间的分歧，保持在整个接触区的成对岛屿。基因组无性系分析也提供了证据的选择和/或杂交不相容性在不同的地区。不同的基因组区域发生在多条染色体上，涉及许多已知的适应性基因座和几种染色体倒位。我们还确定了不同的免疫基因表达谱之间的形式，但没有证据越界表达的杂交。我们的研究结果表明，尽管有一些杂交，生殖隔离仍保持在这个三向接触区中，并且染色体倒位中的重组减少可能在维持这种隔离中发挥重要作用。
Contact zones between divergent forms within a species provide insight into the role of gene flow in adaptation and speciation. Previous work has focused on contact zones involving only two divergent forms, but in nature, many more than two populations may overlap simultaneously and experience gene flow. Patterns of introgression in wild populations are, therefore, likely much more complicated than is often assumed. We begin to address this gap in current knowledge by investigating patterns of divergence and introgression across a complex natural contact zone. We use phenotypic and genomic data to confirm the existence of a three‐way contact zone among divergent freshwater resident, saltwater resident and saltwater migratory three‐spined stickleback (Gasterosteus aculeatus) on the island of North Uist, Scottish Western Isles. We find evidence for hybridization, mostly between saltwater resident and saltwater migratory forms. Despite hybridization, genomic analyses reveal pairwise islands of divergence between all forms that are maintained across the contact zone. Genomic cline analyses also provide evidence for selection and/or hybrid incompatibilities in divergent regions. Divergent genomic regions occur across multiple chromosomes and involve many known adaptive loci and several chromosomal inversions. We also identify distinct immune gene expression profiles between forms, but no evidence for transgressive expression in hybrids. Our results suggest that reproductive isolation is maintained in this three‐way contact zone, despite some hybridization, and that reduced recombination in chromosomal inversions may play an important role in maintaining this isolation.