Application of phylogenomic tools to unravel anthozoan evolution

Comprising approximately 7500 living species of various corals and sea anemones, Anthozoa ranks among the most ecologically and economically valuable marine taxa. However, the taxonomy and systematics of anthozoans remain in flux as several facets of their biology (e.g. cryptic speciation, hybridisation and introgression, morphological plasticity and convergence) confound taxonomists even today. Rapid advancements in molecular sequencing and analyses have made available vast quantities of genomic data on an increasing number of species across the anthozoan tree of life. While whole genome assemblies are expected to result in the most robust phylogenetic trees, reduced-representation techniques such as genome skimming, RAD-seq, phylotranscriptomics and hybrid capture have led to well-supported inferences at various taxonomic levels and may still be favoured at this stage due to the high cost associated with even a single genome assembly. Here, we examine the different genotyping and analytical approaches used in anthozoan phylogeny reconstructions, their applicability across different divergences, and the coverage of studies among anthozoan clades to date. Based on our review of 82 phylogenomic studies, we describe the suitability of methods employed relative to their aims, highlight the imbalanced coverage of taxonomic groups studied and assess immediate and long-term needs where consolidation and streamlining of approaches would further advance the field. Overall, we find that Scleractinia (Anthozoa) is the most phylogenetically sampled group and studies on Octocorallia (Anthozoa) and its subclades are emerging. Nevertheless, we emphasise the need for more phylotranscriptomic, hybrid capture and whole genome sequencing across all anthozoans to increase topological support and generate more precise divergence time estimates. The enhanced phylogenetic understanding of Anthozoa is expected to provide insights into the evolution of genes and adaptations to environmental stressors amidst the current climate and mass extinction crises.

Automated summary

Anthozoa, consisting of approximately 7500 living species of corals and sea anemones, is one of the most ecologically and economically valuable marine taxa. However, taxonomy and systematics of anthozoans remain uncertain due to factors like cryptic speciation and morphological plasticity. Advances in molecular sequencing have provided vast genomic data on anthozoans, but reduced-representation techniques are still favored due to the high cost associated with whole genome assemblies. Further studies are needed to enhance the phylogenetic understanding of Anthozoa and to generate more precise divergence time estimates.