Genetic variation in the massive coral Porites lobata

In recent years, corals have faced increasing anthropogenic disturbances, leading to regional or local reduction in coral species diversity and reduction in genetic variation. The ability of corals to withstand anthropogenic stress, however, differs between genotypes. To be able to estimate survival and recovery potentials, understanding coral genetic variation is therefore of prime scientific interest. This study investigated genetic variation in the massive coral Porites lobata from Moorea, French Polynesia. Colonies were sampled in “family” patches (one large colony surrounded by medium and small sized individuals). We analyzed the allelic diversity of different patches as well as the genotypic variability and relatedness of individual coral colonies. Additionally, intracolonial genetic variability, the harboring of more than a single genotype within a single colony (individual), was analyzed in this species for the first time. In total, 120 coral colonies from three different size clusters (small, medium and large) were investigated with nine microsatellite markers. The three size clusters were used as an assumed proxy for age (juvenile, young adult and adult). The results showed high levels of genetic variation and low levels of relatedness among and within different size classes. All colonies had individual genotypes, suggesting predominantly sexual reproduction. Intracolonial genetic variability was detectable in 25% of the large adults, 15.6% of young adult colonies and 8.8% of juvenile colonies. This is the first evidence of heterogeneous coral colonies in different age classes of P. lobata. The high levels of genetic variation found between and within individuals indicate that P. lobata might have high levels of potential to adapt to a range of natural and anthropogenic disturbances.