Not out of the Mediterranean: Atlantic populations of the gorgonian Paramuricea clavata are a separate sister species under further lineage diversification

The accurate delimitation of species boundaries in non-bilaterian marine taxa is notoriously difficult, with consequences for many studies in ecology and evolution. Anthozoans are a diverse group of key structural organisms worldwide, but the lack of reliable morphological characters and informative genetic markers hampers our ability to understand species diversification. We investigated population differentiation and species limits in Atlantic (Iberian Peninsula) and Mediterranean lineages of the octocoral genus Paramuricea previously identified as P. clavata. We used a diverse set of molecular markers (microsatellites, RNA-seq derived single-copy orthologues [SCO] and mt-mutS [mitochondria]) at 49 locations. Clear segregation of Atlantic and Mediterranean lineages was found with all markers. Species-tree estimations based on SCO strongly supported these two clades as distinct, recently diverged sister species with incomplete lineage sorting, P. cf. grayi and P. clavata, respectively...., ,非两侧对称海洋类群的物种边界精准界定向来极具挑战性，这对诸多生态学与进化生物学研究均会产生连锁影响。珊瑚虫纲是全球范围内种类多样的关键造架生物类群，但可靠形态学特征与有效遗传标记的匮乏，阻碍了我们对物种多样化过程的认知。本研究针对此前被鉴定为P. clavata的八放珊瑚Paramuricea属大西洋（伊比利亚半岛区域）与地中海支系，开展种群分化与物种界限探究。我们在49个采样位点中，采用了涵盖微卫星标记、RNA测序获得的单拷贝同源基因（SCO）以及线粒体mt-mutS基因在内的多类分子标记。所有标记均显示大西洋与地中海支系存在清晰的谱系分化。基于单拷贝同源基因的物种树推断结果强烈支持，这两个演化支为存在不完全谱系分选的、新近分化的姊妹物种，分别对应P. cf. grayi与P. clavata。