Analyzing drivers of speciation in the Southern Ocean using the sea spider species complex Colossendeis megalonyx as a test case
Analyzing drivers of speciation in the Southern Ocean using the sea spider species complex Colossendeis megalonyx as a test case
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DOI：
10.1007/s00300-020-02636-z
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发表时间：
2020-02
期刊：
影响因子：
1.7
通讯作者：
Jana S. Dömel;Lars Dietz;Till-Hendrik Macher;Andrey Rozenberg;C. Mayer;Johanna M. Spaak;R. Melzer;F. Leese
中科院分区：
文献类型：
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作者：
Jana S. Dömel;Lars Dietz;Till-Hendrik Macher;Andrey Rozenberg;C. Mayer;Johanna M. Spaak;R. Melzer;F. Leese
巨型巨蜘蛛是南大洋中分布最广的海蜘蛛。以前的研究已经在这个分类群中发现了几个进化上年轻的谱系，并将其解释为冰川鼎盛时期几个陆架避难所异地物种形成的结果。然而，共生生态物种形成等替代方案很少被考虑或测试。在这里，我们生成了C上最广泛的基因组和形态测量数据。(1)全面描述物种多样性，(2)探索南极洲周围种群之间的种内连通性，(3)系统地测试指示适应性物种形成的正选择。我们成功地应用了目标杂交富集法，回收了所有目标1607个基因。系统发育学分析与以前的发现一致，而且提高了谱系内分支的分辨率。我们发现，在系统发育上分离良好的谱系样本在遗传上彼此不同，相同谱系的地理上分离的种群之间的基因流动受到限制。在与结构和神经功能相关的四个基因中发现了阳性选择的证据。因此，在C中有一个积极选择的迹象。巨型玛瑙物种复杂，但其对物种形成进程的具体贡献仍有待进一步探讨。最后，形态计量分析揭示了不同血统之间的多重显著差异，但事实证明，很难明确区分。我们的研究强调了正向选择作为南大洋物种形成的潜在驱动因素的相关性。
Colossendeis megalonyxHoek, 1881 has the broadest distribution of all sea spiders in the Southern Ocean. Previous studies have detected several evolutionarily young lineages within this taxon and interpreted them as a result of allopatric speciation in a few shelf refuges during glacial maxima. However, alternative scenarios such as ecological speciation in sympatry have rarely been considered or tested. Here, we generated the most extensive genomic and morphometric data set on theC. megalonyxspecies complex to (i) comprehensively describe species diversity, (ii) explore intraspecific connectivity between populations located around Antarctica, and (iii) systematically test for positive selection indicative of adaptive speciation. We successfully applied a target hybrid enrichment approach and recovered all 1607 genes targeted. Phylogenomic analysis was consistent with previous findings and, moreover, increased the resolution of branching within lineages. We found specimens of phylogenetically well-separated lineages occurring in sympatry to be genetically distinct from each other and gene flow between geographically separated populations of the same lineages to be restricted. Evidence for positive selection was found for four genes associated with structural and neuronal functions. Hence, there is an indication for positive selection in theC. megalonyxspecies complex, yet its specific contribution to the speciation process remains to be explored further. Finally, morphometric analyses revealed multiple significant differences between lineages, but a clear separation proved difficult. Our study highlights the relevance of positive selection as a potential driver for speciation in the Southern Ocean.