Quintela María, Johansson Magnus P, Kristjánsson Bjarni K, Barreiro Rodolfo, Laurila Anssi
Dept of Animal Biology, Plant Biology and Ecology, Faculty of Science, University of A Coruña, A Coruña, Spain; Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
PLoS One. 2014 Jul 9;9(7):e101821. doi: 10.1371/journal.pone.0101821. eCollection 2014.
The way environmental variation shapes neutral and adaptive genetic variation in natural populations is a key issue in evolutionary biology. Genome scans allow the identification of the genetic basis of local adaptation without previous knowledge of genetic variation or traits under selection. Candidate loci for divergent adaptation are expected to show higher FST than neutral loci influenced solely by random genetic drift, migration and mutation. The comparison of spatial patterns of neutral markers and loci under selection may help disentangle the effects of gene flow, genetic drift and selection among populations living in contrasting environments. Using the gastropod Radix balthica as a system, we analyzed 376 AFLP markers and 25 mtDNA COI haplotypes for candidate loci and associations with local adaptation among contrasting thermal environments in Lake Mývatn, a volcanic lake in northern Iceland. We found that 2% of the analysed AFLP markers were under directional selection and 12% of the mitochondrial haplotypes correlated with differing thermal habitats. The genetic networks were concordant for AFLP markers and mitochondrial haplotypes, depicting distinct topologies at neutral and candidate loci. Neutral topologies were characterized by intense gene flow revealed by dense nets with edges connecting contrasting thermal habitats, whereas the connections at candidate loci were mostly restricted to populations within each thermal habitat and the number of edges decreased with temperature. Our results suggest microgeographic adaptation within Lake Mývatn and highlight the utility of genome scans in detecting adaptive divergence.
环境变异如何塑造自然种群中的中性和适应性遗传变异是进化生物学中的一个关键问题。基因组扫描能够在无需预先了解遗传变异或选择性状的情况下，识别局部适应性的遗传基础。预计适应性分化的候选基因座比仅受随机遗传漂变、迁移和突变影响的中性基因座表现出更高的FST值。比较中性标记和选择基因座的空间模式，可能有助于厘清生活在不同环境中的种群间基因流、遗传漂变和选择的影响。我们以腹足纲动物巴氏萝卜螺作为研究系统，分析了376个AFLP标记和25个线粒体COI单倍型，以寻找冰岛北部火山湖米湖不同热环境下的候选基因座及其与局部适应性的关联。我们发现，所分析的AFLP标记中有2%受到定向选择，12%的线粒体单倍型与不同的热栖息地相关。AFLP标记和线粒体单倍型的遗传网络是一致的，在中性和候选基因座呈现出不同的拓扑结构。中性拓扑结构的特征是基因流强烈，由连接不同热栖息地的密集网络显示，而候选基因座的连接大多局限于每个热栖息地内的种群，并且边的数量随温度降低。我们的结果表明米湖内存在微地理适应性，并突出了基因组扫描在检测适应性分化方面的效用。
