Scleractinian corals of the genus Pocillopora (Lamarck, 1816) are notoriously difficult to identify morphologically with considerable debate on the degree to which phenotypic plasticity, introgressive hybridization and incomplete lineage sorting obscure well-defined taxonomic lineages. Here, we used RAD-seq to resolve the phylogenetic relationships among seven species of Pocillopora represented by 15 coral holobiont metagenomic libraries. We found strong concordance between the coral holobiont datasets, reads that mapped to the Pocillopora damicornis (Linnaeus, 1758) transcriptome, nearly complete mitochondrial genomes, 430 unlinked high-quality SNPs shared across all Pocillopora taxa, and a conspecificity matrix of the holobiont dataset. These datasets also show strong concordance with previously published clustering of the mitochondrial clades based on the mtDNA open reading frame (ORF). We resolve seven clear monophyletic groups, with no evidence for introgressive hybridization among any but the most recently derived sister species. In contrast, ribosomal and histone datasets, which are most commonly used in coral phylogenies to date, were less informative and contradictory to these other datasets. These data indicate that extant Pocillopora species diversified from a common ancestral lineage within the last ~3 million years. Key to this evolutionary success story may be the high phenotypic plasticity exhibited by Pocillopora species.

Winter, K. B., N. K. Lincoln, F. Berkes, R. A. Alegado, N. Kurashima, K. L. Frank, P. Pascua, Y. M. Rii, F. Reppun, I. S. S. Knapp, W. C. McClatchey, T. Ticktin, C. Smith, E. C. Franklin, K. Oleson, M. R. Price, M. A. McManus, M. J. Donahue, K. S. Rodgers, B. W. Bowen, C. E. Nelson, B. Thomas, J.-A. Leong, E. M. P. Madin, M. A. J. Rivera, K. A. Falinski, L. L. Bremer, J. L. Deenik, S. M. Gon III, B. Neilson, R. Okano, A. Olegario, B. Nyberg, A. H. Kawelo, K. Kotubetey, J. K. Kukea-Shultz, and R. J. Toonen. 2020. Ecomimicry in Indigenous resource management: optimizing ecosystem services to achieve resource abundance, with examples from Hawaiʻi. Ecology and Society 25(2):26. https://doi.org/10.5751/ES-11539-250226

Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building organisms, for example crustose coralline algae (CCA). Here, we use coralline fungal disease (CFD), a previously described CCA disease from the Pacific, to examine these simultaneous effects using both field observations and experimental manipulations. We identify the associated fungus as belonging to the subphylumUstilaginomycetesand show linear lesion expansion rates on individual hosts can reach 6.5 mm per day. Further, we demonstrate for the first time, to our knowledge, that ocean-warming events could increase the frequency of CFD outbreaks on coral reefs, but that OA-induced lowering of pH may ameliorate outbreaks by slowing lesion expansion rates on individual hosts. Lowered pH may still reduce overall host survivorship, however, by reducing calcification and facilitating fungal bio-erosion. Such complex, interactive effects between simultaneous extrinsic environmental stressors on disease dynamics are important to consider if we are to accurately predict the response of coral reef communities to future climate change.