Together stronger: intracolonial genetic variability occurrence in Pocillopora corals suggests potential benefits

We investigated the occurrence of intracolonial genetic variability (IGV) in Pocillopora corals in the Southwestern Indian Ocean. Ninety-six colonies were threefold-sampled from three sites in Reunion Island. Nubbins were genotyped using 13 microsatellite loci and their multilocus genotypes compared. Over 50% of the colonies presented at least two different genotypes among their three nubbins and IGV was found abundant in all sites (from 36.7 to 58.1%). To define the threshold distinguishing mosaicism from chimerism, we developed a new method based on different evolution models by computing the number of different alleles for the Infinite Allele Model (IAM) and the Bruvo’s distance for the Stepwise Mutation Model (SMM). Colonies were considered as chimeras if their nubbins differed from more than four alleles and if the pairwise Bruvo’s distance was higher than 0.12. Thus 80% of the IGV colonies were mosaics and 20% chimeras (representing almost 10% of the total sampling). IGV seems widespread in scleractinians and beyond the disabilities of this phenomenon reported in several studies, it should also bring benefits. Next steps are to identify these benefits and to understand processes leading to IGV, as well as factors influencing them.

This dataset contains the 12 loci genotypes of the 288 nubbins.

本研究针对西南印度洋海域杯形珊瑚属（Pocillopora）珊瑚的群体内遗传变异（intracolonial genetic variability, IGV）发生情况展开调查。研究团队从留尼汪岛的3个采样点采集了96组珊瑚群体，每组均进行3次重复取样。以13个微卫星位点（microsatellite loci）对获取的珊瑚断枝（nubbins）进行基因分型，并对其多位点基因型开展比对分析。结果显示，超过50%的珊瑚群体在其3份断枝样本中至少存在2种不同的基因型；且所有采样点均存在大量IGV现象，占比区间为36.7%至58.1%。为明确区分体细胞镶嵌现象（mosaicism）与嵌合现象（chimerism）的临界阈值，本研究基于不同进化模型开发了一种全新分析方法：分别针对无限等位基因模型（Infinite Allele Model, IAM）计算差异等位基因数量，针对逐步突变模型（Stepwise Mutation Model, SMM）计算布鲁沃距离（Bruvo’s distance）。当珊瑚群体的断枝样本间差异等位基因数超过4个，且两两间布鲁沃距离高于0.12时，该群体即被判定为嵌合体。据此统计，存在IGV的珊瑚群体中80%为体细胞镶嵌体，20%为嵌合体，整体占总采样样本的比例接近10%。群体内遗传变异现象在石珊瑚（scleractinians）中分布广泛；现有多项研究不仅报道了该现象带来的潜在弊端，同时其也可能赋予珊瑚一定益处。后续研究将聚焦于明确此类益处，并解析引发IGV的生物学过程及其影响因素。本数据集包含288份珊瑚断枝的12个位点基因型数据。