High clonality in Acropora palmata and Acropora cervicornis populations of Guadeloupe, French Lesser Antilles

Since the 1980s, population densities of Acroporidae have dramatically declined in the Caribbean Sea. Quantitative censuses of Acroporidae provide information on the number of colonies (i.e. ramets), but not on the number of genetically distinct individuals (i.e. genets). In this context, the aim of our study was to provide an overview of the genetic status of Acropora populations in Guadeloupe by examining the genotypic richness of Acropora palmata and Acropora cervicornis. Using 14 microsatellite loci, we found extremely low genotypic richness for both species from Caye-a-Dupont reef (i.e. 0.125 for A. palmata and nearly zero for A. cervicornis). Because genetic diversity contributes to the ability of organisms to evolve and adapt to new environmental conditions, our results are alarming in the context of ongoing global warming as long periods of clonal growth without sexual recruitment may lead to the extinction of these populations.