Blind to morphology: genetics identifies several widespread ecologically common species and few endemics among Indo‐Pacific cauliflower corals (Pocillopora, Scleractinia)

Abstract

Aim Using high-resolution genetic markers on samples gathered from across their wide distributional range, we endeavoured to delimit species diversity in reef-building Pocillopora corals. They are common, ecologically important, and widespread throughout the Indo-Pacific, but their phenotypic plasticity in response to environmental conditions and their nearly featureless microskeletal structures confound taxonomic assignments and limit an understanding of their ecology and evolution.Location Indo-Pacific, Red Sea, Arabian/Persian Gulf.Methods Sequence analysis of nuclear ribosomal (internal transcribed spacer 2, ITS2) and mitochondrial (open reading frame) loci were combined with population genetic data (seven microsatellite loci) for Pocillopora samples collected throughout the Indo-Pacific, Red Sea and Arabian Gulf, in order to assess the evolutionary divergence, reproductive isolation, frequency of hybridization and geographical distributions of the genus.Results Between five and eight genetically distinct lineages comparable to species were identified with minimal or no hybridization between them. Colony morphology was generally incongruent with genetics across the full range of sampling, and the total number of species is apparently consistent with lower estimates from competing morphologically based hypotheses (about seven or eight taxa). The most commonly occurring genetic lineages were widely distributed and exhibited high dispersal and gene flow, factors that have probably minimized allopatric speciation. Uniquely among scleractinian genera, this genus contains a monophyletic group of broadcast spawners that evolved recently from an ancestral brooder.Main conclusions The delineation of species diversity guided by genetics fundamentally advances our understanding of Pocillopora geographical distributions, ecology and evolution. Because traditional diagnostic features of colony and branch morphology are proving to be of limited utility, the identification of Pocillopora species for future ecological and experimental work should rely on genetic characters that will improve research and aid in conservation strategies for these and other reef-building corals, including the detection of real and mistaken endemic populations.

The New Systematics of Scleractinia: Integrating Molecular and Morphological Evidence

“…Larger geographic contrasts such as between Red Sea and Pacific Ocean populations of Dipsastraea and Stylophora have also revealed molecular separation between regions Arrigoni et al 2012;Keshavmurthy et al 2013). However, to reach a stage where taxonomic revisions can be attempted, broad geographic sampling across the Indo-Pacific and detailed studies of closely-related species are necessary, such as in the case of species in Astreopora (Suzuki and Nomura 2013), Pocillopora (Pinzón and LaJeunesse 2010;Pinzón et al 2012Pinzón et al , 2013Torda et al 2013a, b;Marti-Puig et al 2014;Schmidt-Roach et al 2013, 2014 and Psammocora (Benzoni et al 2010;Stefani et al 2008a). In particular, boundaries among Psammocora species were clarified through a series of rigorous molecular and morphological analyses (Stefani et al 2008a, b;Benzoni et al 2007Benzoni et al , 2010, which saw 24 nominal species reorganised as seven valid species-P. albopicta, P.…”

Marginal coral populations: the densest known aggregation of Pocillopora in the Galápagos Archipelago is of asexual origin

“…Lineages 3a and 3b are only separated by 2 nucleotide changes whereas types 3 and 1 are separated by 14 nucleotide differences (Pinzón and Lajeunesse, 2011). It is not known if mitochondrial lineage types 3a and 3b are sexually compatible (i.e., if they represent different species), however type 3b appears to be rare in the Eastern Pacific (Cunning et al, 2013;Pinzón et al, 2013). Therefore, it is possible that the Isabela colonies represent a founder or remnant genet.…”

“…Here, we extend previous efforts (Combosch and Vollmer, 2011;Pinzón and Lajeunesse, 2011;Cunning et al, 2013;Pinzón et al, 2013) to evaluate the genetic diversity and population structure of Pocillopora in the Eastern Pacific at the geographic margins of this genus' range. By applying multilocus genotyping methods we discovered that the high density stand of Pocillopora corals at Isabela Islands was monogenotypic and aimed to determine whether this clone was a recent colonizer or a survivor of the large-scale ENSO events in 1982/83 and 1997/98.…”

“…Only three evolutionary divergent lineages were found based on mitochondrial sequencing phylogenies and Bayesian clustering analysis (Flot et al, 2008;Pinzón and Lajeunesse, 2011). The mismatch between genetic data and traditional species designations based on morphology calls into question previously published species distributions and occurrences of Pocillopora in the TEP and elsewhere (Combosch and Vollmer, 2011;Pinzón et al, 2013;Schmidt-Roach et al, 2013). A re-evaluation of Pocillopora species distribution in the TEP is thus necessary especially in light of recent large-scale disturbances during ENSO events that can cause local extirpations (Glynn and Deweerdt, 1991;Toth et al, 2012).…”

“…Morphological identification is a challenge (Combosch et al, 2008;Souter, 2010) but sequencing of the mitochondrial ORF allows for designation of distinct lineages (Flot et al, 2008;Souter et al, 2009;Pinzón and Lajeunesse, 2011;Pinzón et al, 2013). Three types (Type 1-3) can be distinguished genetically that appear to be broadcast spawners (Toonen unpubl.…”