Eighteen Coral Genomes Reveal the Evolutionary Origin of Acropora Strategies to Accommodate Environmental Changes

• Published in: Molecular biology and evolution Vol. 38; no. 1; pp. 16 - 30
• Main Authors: Shinzato, Chuya, Khalturin, Konstantin, Inoue, Jun, Zayasu, Yuna, Kanda, Miyuki, Kawamitsu, Mayumi, Yoshioka, Yuki, Yamashita, Hiroshi, Suzuki, Go, Satoh, Noriyuki
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.01.2021
• Subjects: Acropora; Adaptation, Biological; Air pollution; Algae; Animals; Anthozoa - genetics; Antimicrobial peptides; Biological Evolution; Climate Change; Coccoliths; Coral reefs; Coral reefs and islands; Corals; Cretaceous; Dimethyl sulfide; Discoveries; Environmental changes; Enzymes; Eocene; Evolution; Fossils; Gene duplication; Gene transfer; Genes; Genetic aspects; Genome; Genomes; Genomics; Greenhouse gases; Horizontal transfer; Marine ecosystems; Marine environment; Peptides; Positive selection; Sea ice; Sea-water; Seawater; Symbionts; Symbiosis; Water temperature; Whole genome sequencing; Japan; genome sequencing; environment; gene duplicatoin; scleractinian corals
• DOI: 10.1093/molbev/msaa216
• ISSN: 1537-1719; 0737-4038

The genus Acropora comprises the most diverse and abundant scleractinian corals (Anthozoa, Cnidaria) in coral reefs, the most diverse marine ecosystems on Earth. However, the genetic basis for the success and wide distribution of Acropora are unknown. Here, we sequenced complete genomes of 15 Acropora species and 3 other acroporid taxa belonging to the genera Montipora and Astreopora to examine genomic novelties that explain their evolutionary success. We successfully obtained reasonable draft genomes of all 18 species. Molecular dating indicates that the Acropora ancestor survived warm periods without sea ice from the mid or late Cretaceous to the Early Eocene and that diversification of Acropora may have been enhanced by subsequent cooling periods. In general, the scleractinian gene repertoire is highly conserved; however, coral- or cnidarian-specific possible stress response genes are tandemly duplicated in Acropora. Enzymes that cleave dimethlysulfonioproprionate into dimethyl sulfide, which promotes cloud formation and combats greenhouse gasses, are the most duplicated genes in the Acropora ancestor. These may have been acquired by horizontal gene transfer from algal symbionts belonging to the family Symbiodiniaceae, or from coccolithophores, suggesting that although functions of this enzyme in Acropora are unclear, Acropora may have survived warmer marine environments in the past by enhancing cloud formation. In addition, possible antimicrobial peptides and symbiosis-related genes are under positive selection in Acropora, perhaps enabling adaptation to diverse environments. Our results suggest unique Acropora adaptations to ancient, warm marine environments and provide insights into its capacity to adjust to rising seawater temperatures.