Data from: Mitochondrial haplotypes indicate parapatric-like phylogeographic structure in blue-spotted maskray (Neotrygon kuhlii) from the Coral Triangle region

Phylogeographic structure was investigated in the blue-spotted maskray, Neotrygon kuhlii, focusing on the Coral Triangle region. We used as genetic marker a 519-bp fragment of the cytochrome c-oxidase subunit I (COI) gene, sequenced in a total of 147 individuals from 26 sampling locations. The parsimony network of COI haplotypes was split into seven distinct clades within the Coral Triangle region. Different clades had exclusive but contiguous geographic distributions, indicating parapatric-like phylogeographic structure. Strong genetic differences were also inferred between local populations within a clade, where reciprocal monophyly between geographically adjacent samples was observed on several instances. Nearly 25% of the total molecular variance could be ascribed to differences between geographic samples within a clade, whereas interclade variation accounted for >65% of the total variance. The strong phylogeographic structure observed within a clade can be explained by either sedentarity or female philopatry. We interpret the parapatric distribution of clades as the joint result of 1) expansion from refuge populations at times of low sea level, and 2) possible enhanced competition between individuals from different clades, or assortative mating, or hybrid zones, along lines of secondary contact. The parapatric-like structure uncovered in the present study parallels regional differences at nuclear marker loci, thus pointing to incipient speciation within Coral Triangle N. kuhlii.

本研究以珊瑚三角区（Coral Triangle）为核心研究区域，针对蓝斑条尾魟（Neotrygon kuhlii）的系统地理学结构展开了调查。本研究选取细胞色素c氧化酶亚基I（cytochrome c-oxidase subunit I, COI）基因的519 bp片段作为遗传标记，对采自26个采样点的共计147个个体完成了测序。COI单倍型的简约网络在珊瑚三角区内被划分为7个独立的进化枝，各进化枝均具有排他性但连续的地理分布，这表明该类群存在类邻域（parapatric-like）系统地理学结构。在单个进化枝内部的本地种群间，同样检测到显著的遗传分化，多个案例中观察到地理相邻的样本间存在互惠单系现象。总分子变异的近25%可归因于进化枝内部地理样本间的差异，而进化枝间的变异占总变异的65%以上。进化枝内部所观察到的强系统地理学结构，可通过定居性或雌性归巢行为（female philopatry）加以解释。我们将进化枝的类邻域分布解读为两大因素共同作用的结果：1）低海平面时期从避难所种群的扩张；2）不同进化枝个体间可能存在的增强竞争、选型交配（assortative mating）或次级接触带杂交区的形成。本研究揭示的类邻域结构与核标记位点的区域差异相一致，由此表明珊瑚三角区内的蓝斑条尾魟正处于物种形成初期。