Combosch David J, Vollmer Steven V
Northeastern University, Marine Science Center, 430 Nahant Road, 01908 Nahant, MA, USA.
Northeastern University, Marine Science Center, 430 Nahant Road, 01908 Nahant, MA, USA.
Mol Phylogenet Evol. 2015 Jul;88:154-62. doi: 10.1016/j.ympev.2015.03.022. Epub 2015 Apr 4.
Discrepancies between morphology-based taxonomy and phylogenetic systematics are common in Scleractinian corals. In Pocillopora corals, nine recently identified genetic lineages disagree fundamentally with the 17 recognized Pocillopora species, including 5 major Indo-Pacific reef-builders. Pocillopora corals hybridize in the Tropical Eastern Pacific, so it is possible that some of the disagreement between the genetics and taxonomy may be due to introgressive hybridization. Here we used 6769 genome-wide SNPs from Restriction-site Associated DNA Sequencing (RAD-Seq) to conduct phylogenomic comparisons among three common, Indo-Pacific Pocillopora species - P. damicornis, P. eydouxi and P. elegans - within and between populations in the Tropical Eastern Pacific (TEP) and the Central Pacific. Genome-wide RAD-Seq comparisons of Central and TEP Pocillopora confirm that the morphospecies P. damicornis, P. eydouxi and P. elegans are not monophyletic, but instead fall into three distinct genetic groups. However, hybrid samples shared fixed alleles with their respective parental species and, even without strict monophyly, P. damicornis share a common set of 33 species-specific alleles across the Pacific. RAD-Seq data confirm the pattern of one-way introgressive hybridization among TEP Pocillopora, suggesting that introgression may play a role in generating shared, polyphyletic lineages among currently recognized Pocillopora species. Levels of population differentiation within genetic lineages indicate significantly higher levels of population differentiation in the Tropical Eastern Pacific than in the Central West Pacific.
基于形态学的分类法与系统发育系统学之间的差异在石珊瑚中很常见。在鹿角珊瑚属珊瑚中，最近确定的9个遗传谱系与17个已确认的鹿角珊瑚属物种根本不一致，其中包括5种主要的印度-太平洋造礁珊瑚。鹿角珊瑚属珊瑚在热带东太平洋杂交，因此遗传学与分类学之间的一些分歧可能是由于渐渗杂交。在这里，我们使用来自限制性位点相关DNA测序（RAD-Seq）的6769个全基因组单核苷酸多态性（SNP），对热带东太平洋（TEP）和中太平洋的三个常见的印度-太平洋鹿角珊瑚属物种——多孔鹿角珊瑚、艾氏鹿角珊瑚和秀丽鹿角珊瑚——种群内部和种群之间进行系统发育基因组比较。对中太平洋和热带东太平洋鹿角珊瑚属的全基因组RAD-Seq比较证实，形态物种多孔鹿角珊瑚、艾氏鹿角珊瑚和秀丽鹿角珊瑚并非单系的，而是分为三个不同的遗传群体。然而，杂交样本与其各自的亲本物种共享固定等位基因，并且即使没有严格的单系性，多孔鹿角珊瑚在整个太平洋也共享一组33个物种特异性等位基因。RAD-Seq数据证实了热带东太平洋鹿角珊瑚属之间单向渐渗杂交的模式，这表明渐渗可能在目前公认的鹿角珊瑚属物种中产生共享的多系谱系中发挥作用。遗传谱系内的种群分化水平表明，热带东太平洋的种群分化水平明显高于中西部太平洋。
