Adaptation to Low Salinity Promotes Genomic Divergence in Atlantic Cod (Gadus morhua L.).
Adaptation to Low Salinity Promotes Genomic Divergence in Atlantic Cod (Gadus morhua L.).
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DOI：
10.1093/gbe/evv093
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发表时间：
2015-05-20
影响因子：
3.3
通讯作者：
André C
中科院分区：
文献类型：
--
作者：
Berg PR;Jentoft S;Star B;Ring KH;Knutsen H;Lien S;Jakobsen KS;André C
基因组选择如何使物种适应不同的环境是生态学和进化中的一个基本问题。我们调查了大西洋鳕鱼（Gadus morhua L.）沿着自然盐度梯度，从北海的35‰到波罗的海的7‰。通过利用12 K SNP芯片，我们同时评估了大西洋鳕鱼基因组的中性和适应性遗传差异。结合离群值分析与景观基因组的方法，我们确定了一组定向选择的位点，强烈相关的盐度，氧气和温度的栖息地差异。我们的研究结果表明，大西洋鳕鱼基因组内的离散区域受到定向选择和适应当地的环境条件在波罗的海和北海，表明分歧搭便车和存在的基因组岛屿的分歧。我们报告了一套离群单核苷酸多态性内或密切定位于与β调节相关的基因，以及已知在卵母细胞的水合和发育中发挥重要作用的基因。这些基因很可能在一个一般的鱼的监管框架内的关键功能，是重要的卵和幼虫的生存，有助于建立低盐度适应的波罗的海鳕鱼和邻近的鳕鱼种群之间的生殖隔离。因此，我们的数据表明，在波罗的海的环境条件的适应性反应可能有助于强大而有效的生殖屏障，波罗的海鳕鱼可以被视为正在进行的物种形成的一个例子。
How genomic selection enables species to adapt to divergent environments is a fundamental question in ecology and evolution. We investigated the genomic signatures of local adaptation in Atlantic cod (Gadus morhua L.) along a natural salinity gradient, ranging from 35‰ in the North Sea to 7‰ within the Baltic Sea. By utilizing a 12 K SNPchip, we simultaneously assessed neutral and adaptive genetic divergence across the Atlantic cod genome. Combining outlier analyses with a landscape genomic approach, we identified a set of directionally selected loci that are strongly correlated with habitat differences in salinity, oxygen, and temperature. Our results show that discrete regions within the Atlantic cod genome are subject to directional selection and associated with adaptation to the local environmental conditions in the Baltic- and the North Sea, indicating divergence hitchhiking and the presence of genomic islands of divergence. We report a suite of outlier single nucleotide polymorphisms within or closely located to genes associated with osmoregulation, as well as genes known to play important roles in the hydration and development of oocytes. These genes are likely to have key functions within a general osmoregulatory framework and are important for the survival of eggs and larvae, contributing to the buildup of reproductive isolation between the low-salinity adapted Baltic cod and the adjacent cod populations. Hence, our data suggest that adaptive responses to the environmental conditions in the Baltic Sea may contribute to a strong and effective reproductive barrier, and that Baltic cod can be viewed as an example of ongoing speciation.
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