Evolutionary biogeography of the reef-building coral genus Galaxea across the Indo-Pacific ocean

• Published in: Molecular phylogenetics and evolution 2020-10, Vol.151, p.106905-106905, Article 106905
• Main Authors: Wepfer, Patricia H., Nakajima, Yuichi, Sutthacheep, Makamas, Radice, Veronica Z., Richards, Zoe, Ang, Put, Terraneo, Tullia, Sudek, Mareike, Fujimura, Atsushi, Toonen, Robert J., Mikheyev, Alexander S., Economo, Evan P., Mitarai, Satoshi
• Format: Article
• Language: English
• Subjects: Animals; Anthozoa - classification; Anthozoa - genetics; Base Sequence; Biogeography; Chagos; Coral Reefs; Cryptic species; DNA, Mitochondrial - genetics; Galaxea; Genetic Variation; Haplotypes - genetics; Indian Ocean; Indo-Pacific; Mitochondria - genetics; Mitochondrial haplotype analysis; Pacific Ocean; Phylogenetics; Phylogeny; Phylogeography; Principal Component Analysis; RAD-seq; Scleractinia
• ISSN: 1055-7903; 1095-9513
• DOI: 10.1016/j.ympev.2020.106905

[Display omitted] •Galaxea contains three distinct clades: an Indo-Pacific, a Pacific, and one restricted to the Chagos Archipelago.•Galaxea fascicularis is polyphyletic and may be divided into six cryptic lineages throughout the Indo-Pacific.•The non-coding region between mt-cytb and -ND is highly conserved apart from a characteristic deletion in lineage S of G. fascicularis.•Galaxea horrescens is the only monophyletic species confirmed. Stony corals (Scleractinia) form the basis for some of the most diverse ecosytems on Earth, but we have much to learn about their evolutionary history and systematic relationships. In order to improve our understanding of species in corals we here investigated phylogenetic relationships between morphologically defined species and genetic lineages in the genus Galaxea (Euphyllidae) using a combined phylogenomic and phylogeographic approach. Previous studies revealed the nominal species G. fascicularis included three genetically well-differentiated lineages (L, S & L+) in the western Pacific, but their distribution and relationship to other species in the genus was unknown. Based on genomic (RAD-seq) and mitochondrial sequence data (non-coding region between cytb and ND2) we investigated whether the morphological taxa represent genetically coherent entities and what is the phylogenetic relationship and spatial distribution of the three lineages of G. fascicularis throughout the observed species range. Using the RAD-seq data, we find that the genus Galaxea is monophyletic and contains three distinct clades: an Indo-Pacific, a Pacific, and a small clade restricted to the Chagos Archipelago. The three lineages of G. fascicularis were associated with different RAD-seq clades, with the ‘L’ lineage showing some morphological distinction from the other two lineages (larger more asymmetrical polyps). In addition to these, three more genetic lineages in G. fascicularis may be distinguished – a Chagossian, an Ogasawaran, and one from the Indian-Red Sea. Among nominal taxa for which we have multiple samples, G. horrescens was the only monophyletic species. The mitochondrial non-coding region is highly conserved apart of the length polymorphism used to define L, S & L+ lineages and lacks the power to distinguish morphological and genetic groups resolved with genomic RAD-sequencing. The polyphyletic nature of most species warrants a careful examination of the accepted taxonomy of this group with voucher collections and their comparison