Data from: Within-population structure highlighted by differential introgression across semipermeable barriers to gene flow in Anguilla marmorata

In the marine environment, differential gene exchange between partially reproductively isolated taxa can result in introgression that extends over long distances due to high larval dispersal potential. However, the degree to which this process contributes to inter-locus variance of genetic differentiation within introgressed populations remains unclear. Using a genome-scan approach in the Indo-Pacific eel Anguilla marmorata, we investigated the degree of interpopulation genetic differentiation, the rate of introgression, and within-population genetic patterns at 858 AFLP markers genotyped in 1117 individuals. Three divergent populations were identified based on clustering analysis. Genetic assignments of individuals revealed the existence of different types of hybrids that tended to co-occur with parental genotypes in three population contact zones. Highly variable levels of genetic differentiation were found between populations across the AFLP markers, and reduced rates of introgression were shown at some highly differentiated loci. Gene flow across semipermeable genetic barriers was shown to generate spatial introgression patterns at some loci which define within-population structure over long distances. These results suggest that differential introgression in subdivided populations may be relevant when interpreting spatial variation patterns displayed by outlying loci in other marine fish populations.

在海洋环境中，部分生殖隔离的类群间的差异化基因交换，可因幼体具备高扩散潜力而产生远距离渐渗（introgression）。然而，该过程对渐渗种群内遗传分化的位点间方差的贡献程度，目前仍不明确。本研究以印度-太平洋海域的花鳗鲡（Anguilla marmorata）为研究对象，采用基因组扫描（genome scan）方法，对1117个个体的858个扩增片段长度多态性（Amplified Fragment Length Polymorphism, AFLP）标记进行基因分型，进而解析种群间遗传分化程度、渐渗速率与种群内遗传模式。通过聚类分析，本研究共鉴定出3个分化种群。个体遗传分型结果显示，存在多种杂交型个体，且这些杂交型往往与亲本基因型共同出现于三个种群接触带中。基于AFLP标记的分析发现，种群间的遗传分化水平存在显著差异；同时部分高度分化的位点表现出较低的渐渗速率。跨越半透性遗传屏障的基因流，可在部分位点形成空间渐渗模式，该模式可在大尺度上塑造种群内的遗传结构。本研究结果提示，在解读其他海洋鱼类种群中离群位点所呈现的空间变异模式时，亚分化种群内的差异化渐渗过程或具有关键参考价值。