High levels of interspecific gene flow in an endemic cichlid fish adaptive radiation from an extreme lake environment.
High levels of interspecific gene flow in an endemic cichlid fish adaptive radiation from an extreme lake environment.
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DOI：
10.1111/mec.13247
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发表时间：
2015-07
影响因子：
4.9
通讯作者：
Day JJ
中科院分区：
文献类型：
--
作者：
Ford AG;Dasmahapatra KK;Rüber L;Gharbi K;Cezard T;Day JJ
研究最近的适应性辐射在孤立的岛屿系统避免复杂的因果事件，从而可以提供更清晰的洞察机制产生生物多样性。在这里，我们调查的进化关系和基因组分化最近的辐射Alcolapia慈鲷鱼表现出广泛的表型多样化，并仅限于极端苏打湖马加迪和纳特龙在东非。我们产生了一个广泛的RAD数据集的96个人从多个采样点，并发现证据表明，在纳特龙湖内的物种之间的遗传混合物，最高水平的混合物最近分歧的物种同域种群之间。尽管有相当大的环境分离，人口在纳特龙湖不表现出隔离的距离，表明panmixia内的湖泊，虽然个人的谱系内的人口聚集在基因组分析。我们的研究结果表明，尽管有相当大的表型营养变异，但辐射范围内的遗传分化异常低，支持以前较小数据集的研究结果;然而，随着密集采样SNP的功率增加，我们确定了Alcolapia物种之间的分化（F ST离群值）的基因组峰值。虽然在某些人群中正在进行的基因流和种间杂交的证据表明，Alcolapia物种是不完全生殖隔离，离群SNP的识别多样化的选择表明辐射正在经历适应性分歧。
Studying recent adaptive radiations in isolated insular systems avoids complicating causal events and thus may offer clearer insight into mechanisms generating biological diversity. Here, we investigate evolutionary relationships and genomic differentiation within the recent radiation of Alcolapia cichlid fish that exhibit extensive phenotypic diversification, and which are confined to the extreme soda lakes Magadi and Natron in East Africa. We generated an extensive RAD data set of 96 individuals from multiple sampling sites and found evidence for genetic admixture between species within Lake Natron, with the highest levels of admixture between sympatric populations of the most recently diverged species. Despite considerable environmental separation, populations within Lake Natron do not exhibit isolation by distance, indicating panmixia within the lake, although individuals within lineages clustered by population in phylogenomic analysis. Our results indicate exceptionally low genetic differentiation across the radiation despite considerable phenotypic trophic variation, supporting previous findings from smaller data sets; however, with the increased power of densely sampled SNPs, we identify genomic peaks of differentiation (F ST outliers) between Alcolapia species. While evidence of ongoing gene flow and interspecies hybridization in certain populations suggests that Alcolapia species are incompletely reproductively isolated, the identification of outlier SNPs under diversifying selection indicates the radiation is undergoing adaptive divergence.