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.

在海洋生态系统中，由于幼虫具备极强的扩散潜力，部分生殖隔离的分类群（taxa）之间的差异化基因交流可引发基因渐渗（introgression），并使其传播至远距离范围。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，目前仍未明确。本研究以印度-太平洋花鳗鲡（Anguilla marmorata）为研究对象，采用基因组扫描（genome-scan）技术，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，以此解析种群间遗传分化水平、基因渐渗速率以及种群内遗传模式。通过聚类分析，本研究共鉴定出3个分化种群。个体遗传归属分析结果显示，存在多种杂种类型，这些杂种往往与亲本基因型共同存在于三个种群接触带中。基于AFLP标记的分析表明，种群间的遗传分化水平存在显著异质性，且部分高度分化的位点上基因渐渗速率有所降低。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，这类模式从远距离尺度上界定了种群内部的遗传结构。本研究结果提示，在解读其他海洋鱼类种群中外围位点所呈现的空间变异模式时，分化种群内的差异化渐渗过程或具备重要的参考意义。