Data from: More than one genotype: How common is intracolonial genetic variability in scleractinian corals?

In recent years, a few colonial marine invertebrates have shown intracolonial genetic variability, a previously unreported phenomenon. Intracolonial genetic variability describes the occurrence of more than a single genotype within an individual colony. This variability can be traced back to two underlying processes: chimerism and mosaicism. Chimerism is the fusion of two or more individuals, whereas mosaicism mostly derives from somatic cell mutations. Until now, it remained unclear to what degree the ecologically important group of hermatypic (reef building) corals might be affected. We investigate the occurrence of intracolonial genetic variability in five scleractinian corals: Acropora florida, Acropora hyacinthus, Acropora sarmentosa, Pocillopora species complex and Porites australiensis. The main focus was to test different genera for the phenomenon via microsatellite markers and to distinguish which underlying process caused the genetic heterogeneity. Our results show that intracolonial genetic variability was common (between 46.6% for A. sarmentosa and 23.8% for P. species complex) in all tested corals. The main process was mosaicism (69 cases of 222 tested colonies), but at least one chimera existed in every species. This suggests that intracolonial genetic variability is widespread in scleractinian corals and could challenge the view of a coral colony as an individual and therefore a unit of selection. However, it might also hold potential for colony survival under rapidly changing environmental conditions.

近年来，部分群居海洋无脊椎动物已被证实存在群体内遗传变异（intracolonial genetic variability）——这是此前未被报道过的现象。群体内遗传变异指单个群居个体内存在不止一种基因型的情况。该类变异可追溯至两种潜在过程：嵌合性（chimerism）与镶嵌性（mosaicism）。其中嵌合性指两个或多个个体的融合，而镶嵌性则主要源于体细胞突变。截至目前，生态功能至关重要的造礁珊瑚（hermatypic corals）群体受该现象影响的程度仍不明确。本研究针对5种石珊瑚目珊瑚（scleractinian corals）开展了群体内遗传变异发生率的调查，受试类群包括Acropora florida、Acropora hyacinthus、Acropora sarmentosa、Pocillopora species complex及Porites australiensis。本研究的核心目标为通过微卫星标记（microsatellite markers）检测不同属珊瑚是否存在该现象，并明确导致遗传异质性（genetic heterogeneity）的潜在分子过程。研究结果显示，所有受试珊瑚中均普遍存在群体内遗传变异，检出率范围为Acropora sarmentosa的46.6%至Pocillopora species complex的23.8%。其中主要的潜在过程为镶嵌性：222个受试群居个体中共有69例符合该特征，但所有受试珊瑚物种中均至少存在1例嵌合性案例。这表明群体内遗传变异在石珊瑚目珊瑚中广泛存在，或将颠覆“珊瑚群居个体为单一进化个体、进而作为选择单元”的传统认知。但该现象也可能为群居个体在快速变化的环境条件下的存活提供潜在优势。