The contribution of ancient admixture to reproductive isolation between European sea bass lineages
The contribution of ancient admixture to reproductive isolation between European sea bass lineages
复制标题
DOI：
10.1002/evl3.169
复制
发表时间：
2020-06-01
影响因子：
5
通讯作者：
Gagnaire, Pierre-Alexandre
中科院分区：
文献类型：
--
作者：
Duranton, Maud;Allal, Francois;Gagnaire, Pierre-Alexandre
了解新物种是如何通过逐步建立不同种群之间的生殖隔离（RI）障碍而产生的，是进化生物学的一个主要目标。物种形成基因组学研究的一个重要结果是，RI所涉及的基因组区域经常具有古老的分化单倍型，这些单倍型早于物种分化的重建历史。这些古老等位基因的可能起源仍然存在很大争议，因为它们与尚未完全理解的物种形成机制有关。在欧洲海鲈鱼（Dicentrarchus labrax），基因组区域参与RI大西洋和地中海血统之间的丰富的古老分歧的等位基因来源不明。在这里，我们使用单倍型解析的全基因组序列来测试不同的单倍型是否可能起源于一个密切相关的物种，斑点鲈鱼（Dicentrarchus punctatus）。我们发现D. labrax和D. punctatus是负责的存在共享的衍生等位基因，分离在低频率的两个谱系的D。拉布拉多一个例外，这是发现在两个D之间的RI所涉及的区域内。拉布拉多血统在这些地区，起源于D. punctatus在大西洋的基因组中出现频率很高，甚至固定下来，但在地中海几乎不存在。我们发现，古代混合事件最有可能发生在D。punctatus和D. Labrax大西洋血统，而大西洋和地中海D.拉布拉多谱系正在经历异地隔离。我们的研究结果表明，当地的适应性渐渗和/或古老的混合物引起的基因组冲突的决议可能有助于建立两个之间的RI。拉布拉多血统
Understanding how new species arise through the progressive establishment of reproductive isolation (RI) barriers between diverging populations is a major goal in Evolutionary Biology. An important result of speciation genomics studies is that genomic regions involved in RI frequently harbor anciently diverged haplotypes that predate the reconstructed history of species divergence. The possible origins of these old alleles remain much debated, as they relate to contrasting mechanisms of speciation that are not yet fully understood. In the European sea bass (Dicentrarchus labrax), the genomic regions involved in RI between Atlantic and Mediterranean lineages are enriched for anciently diverged alleles of unknown origin. Here, we used haplotype-resolved whole-genome sequences to test whether divergent haplotypes could have originated from a closely related species, the spotted sea bass (Dicentrarchus punctatus). We found that an ancient admixture event betweenD. labraxandD. punctatusis responsible for the presence of shared derived alleles that segregate at low frequencies in both lineages ofD. labrax. An exception to this was found within regions involved in RI between the twoD. labraxlineages. In those regions, archaic tracts originating fromD. punctatuslocally reached high frequencies or even fixation in Atlantic genomes but were almost absent in the Mediterranean. We showed that the ancient admixture event most likely occurred betweenD. punctatusand theD. labraxAtlantic lineage, while Atlantic and MediterraneanD. labraxlineages were experiencing allopatric isolation. Our results suggest that local adaptive introgression and/or the resolution of genomic conflicts provoked by ancient admixture have probably contributed to the establishment of RI between the twoD. labraxlineages.