Multilocus coalescent analysis of haemoglobin differentiation between low- and high-altitude populations of crested ducks (Lophonetta specularioides)
Multilocus coalescent analysis of haemoglobin differentiation between low- and high-altitude populations of crested ducks (Lophonetta specularioides)
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DOI：
10.1111/j.1365-294x.2011.05400.x
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发表时间：
2012-01-01
影响因子：
4.9
通讯作者：
McCracken, Kevin G.
中科院分区：
文献类型：
--
作者：
Bulgarella, Mariana;Peters, Jeffrey L.;McCracken, Kevin G.
缺氧是决定生存的关键因素，血红蛋白是高海拔地区物种选择的目标。我们研究了种群遗传结构和评估的证据，当地适应的凤头鸭（Lophonetta specularioides）。对3个血红蛋白基因（α（A）、α（D）、β（A））的高地和低地人群之间的分化、基因流和分化时间进行了评估，并与7个参考位点（6个常染色体内含子和mtDNA）进行了比较。在安第斯高地和巴塔哥尼亚低地之间的Phi ST值升高的珠蛋白基因中发现了四个衍生的氨基酸替换。一个单一的β（A）-珠蛋白多态性在一个已知的影响O-2亲和力的网站是固定的两个群体中的不同等位基因，而三个α（A）-和α（D）-珠蛋白多态性表现出高杂合性在高地，但不是在低地。合并分析支持血红蛋白等位基因和线粒体DNA的限制基因流，但内含子的非零基因流。在选择中性的漂移-迁移模型下模拟遗传数据，β（A）-珠蛋白落在模拟数据的95%置信限之外，表明定向选择在对比的海拔环境中保持不同的变体，从而限制β（A）-珠蛋白等位基因的迁移。相比之下，α（A）-和α（D）-球蛋白与模拟值没有差异，这表明这些基因中的变体要么是选择性中性的，要么选择的影响不能从群体结构和连锁不平衡的背景水平中区分出来。这项研究说明了选择和人口的历史推断水平的人口分化分布在一个海拔梯度，其中耐缺氧选择可能发挥了重要作用的物种的综合影响。
Hypoxia is a key factor determining survival, and haemoglobins are targets of selection in species native to high-altitude regions. We studied population genetic structure and evaluated evidence for local adaptation in the crested duck (Lophonetta specularioides). Differentiation, gene flow and time since divergence between highland and lowland populations were assessed for three haemoglobin genes (alpha(A), alpha(D), beta(A)) and compared to seven reference loci (six autosomal introns and mtDNA). Four derived amino acid replacements were found in the globin genes that had elevated Phi ST values between the Andean highlands and Patagonian lowlands. A single beta(A)-globin polymorphism at a site known to influence O-2 affinity was fixed for different alleles in the two populations, whereas three alpha(A)- and alpha(D)-globin polymorphisms exhibited high heterozygosity in the highlands but not in the lowlands. Coalescent analyses supported restricted gene flow for haemoglobin alleles and mitochondrial DNA but nonzero gene flow for the introns. Simulating genetic data under a drift-migration model of selective neutrality, the beta(A)-globin fell outside the 95% confidence limit of simulated data, suggesting that directional selection is maintaining different variants in the contrasting elevational environments, thereby restricting migration of beta(A)-globin alleles. The alpha(A)- and alpha(D)-globins, by contrast, did not differ from the simulated values, suggesting that variants in these genes are either selectively neutral, or that the effects of selection could not be differentiated from background levels of population structure and linkage disequilibrium. This study illustrates the combined effects of selection and population history on inferring levels of population divergence for a species distributed across an altitudinal gradient in which selection for hypoxia resistance has likely played an important role.