Effect of tropical storms on sexual and asexual reproduction in coral Pocillopora verrucosa subpopulations in the Gulf of California

Abstract

Pocillopora verrucosa is a branching, reef-building coral, and a simultaneous hermaphrodite that reproduces sexually and asexually by fragmentation. In the Gulf of California, local P. verrucosa populations have mixed modes of reproduction which vary in frequency by site. Sexual and asexual reproductions were assessed using multi-locus genotypes deriving from six microsatellite loci at every location. Clone frequencies varied from 0.30 at Loreto to 0.96 in the San Lorenzo Channel. Isla Espiritu Santo and the San Lorenzo Channel were mostly asexual subpopulations, presented the lowest genotypic richness (N g /N = 0.1–0.12) and genotypic diversity (G o /G e = 0.04), and were dominated by one or two multi-loci genotypes (G o /N g = 0.35–0.45). Loreto, El Portugues, and Cabo Pulmo were mostly sexual with high Ng/N (0.80–0.74) and G o /G e (0.52–0.58) and did not show domination by a single multi-locus genotype (G o /N g = 0.70–0.74). There was a significant relationship (P < 0.05) between tropical storm frequency and the genotypic indexes of richness and diversity modeling an inverted U-shape, which indicates that the sites where storm frequencies were the highest had mostly clonal populations; sites exposed to intermediate or low storm frequencies had mostly sexual populations. The study included a restored area (San Lorenzo Channel) where genotypic analyses showed a high level of clonality similar to natural conditions occurring in a nearby subpopulation (Isla Espiritu Santo), which demonstrates the low natural genetic diversity of the area. This study showed that a species with mixed reproduction modes has different maintenance strategies at a regional and even local level among populations indicating the crucial role that storms play in population structure.