From Population Connectivity To The Art Of Striping Russian Dolls: The Lessons From Pocillopora Corals

Here, we examined the genetic variability in the coral genus <em>Pocillopora</em>, in particular within the Primary Species Hypothesis PSH09, identified by Gélin, Postaire, Fauvelot and Magalon (2017b) using species delimitation methods [also named <em>Pocillopora eydouxi/meandrina</em> complex <em>sensu</em> Schmidt-Roach, Miller, Lundgren, &amp; Andreakis (2014)] and which was found to split into three Secondary Species Hypotheses (SSH09a, SSH09b and SSH09c) according to assignment tests using multi-locus genotypes (13 microsatellites). From a large sampling (2,507 colonies) achieved in three marine provinces [Western Indian Ocean (WIO), Tropical Southwestern Pacific (TSP) and Southeast Polynesia (SEP)], genetic structuring analysis conducted with two clustering analyses (Structure and DAPC) using 13 microsatellites revealed that SSH09a was restricted to the WIO while SSH09b and SSH09c were almost exclusively in the TSP and SEP. More surprisingly, each SSH split into two to three genetically differentiated clusters, found in sympatry at the reef scale, leading to a pattern of nested hierarchical levels (PSH &gt; SSH &gt; cluster), each level hiding highly differentiated genetic groups. Thus, rather than structured populations within a single species, these three SSHs, and even the eight clusters, likely represent distinct genetic lineages engaged in a speciation process or real species. The issue is now to understand which hierarchical level (SSH, cluster or even below) corresponds to the species one. Several hypotheses are discussed on the processes leading to this pattern of mixed clusters in sympatry, evoking formation of reproductive barriers, either by allopatric speciation or habitat selection. This submission contains the genotypes of 2507 individuals from PSH09 for 13 microsatellites.本研究针对杯形珊瑚属（Pocillopora）的遗传变异展开系统分析，重点聚焦于Gélin、Postaire、Fauvelot与Magalon（2017b）通过物种界定方法识别的首要物种假说（Primary Species Hypothesis）PSH09——该类群亦被Schmidt-Roach、Miller、Lundgren及Andreakis（2014）定义为<em>Pocillopora eydouxi/meandrina</em>复合类群（sensu）。经基于多位点基因型（13个微卫星位点）的归属分析验证，PSH09可进一步划分为3个次级物种假说（SSH09a、SSH09b与SSH09c）。研究依托覆盖3个海洋生物地理区的大规模采样（共2507个珊瑚群体），即西印度洋（Western Indian Ocean, WIO）、热带西南太平洋（Tropical Southwestern Pacific, TSP）与东南波利尼西亚（Southeast Polynesia, SEP）；利用13个微卫星位点，通过Structure与DAPC两种聚类分析方法开展遗传结构解析，结果显示SSH09a仅局限分布于WIO区域，而SSH09b与SSH09c则几乎仅见于TSP与SEP区域。更为出乎意料的是，每个次级物种假说均可进一步拆分为2至3个遗传分化显著的类群，这些类群在礁体尺度下呈现同域分布特征，由此形成了嵌套式层级结构（首要物种假说 > 次级物种假说 > 类群），每一层级均对应着遗传分化程度极高的遗传群体。据此推测，这3个次级物种假说乃至后续划分的8个类群，并非单一物种内部的结构化种群，而是极有可能代表了处于物种形成进程中的独立遗传谱系，或是真正的独立物种。当前亟需厘清的核心问题是，哪一层级（次级物种假说、类群，乃至更低层级）对应着生物学物种的界定标准。本研究还针对同域分布类群的形成机制提出多项假说并展开探讨，涉及异域物种形成或生境选择所介导的生殖隔离形成过程。 本提交数据集包含了来自PSH09的2507个个体的13个微卫星位点基因型数据。