Genetic Divergence and Connectivity among Gene Pools of Polyprion americanus.

Abstract

Three regional gene pools of Polyprion americanus have been described so far, i.e., the North Atlantic, the Southwest Atlantic, and the Indo-Pacific Ocean. However, there is taxonomic uncertainty about the Southeast Atlantic population and there is suspicion on the existence of a third species of Polyprion in that area. Additionally, prior studies have shown a lack of genetic structuring in the Atlantic North. Nonetheless, a more conspicuous characterization of intensity, periodicity, and direction of migration are needed to properly understand the wreckfish connectivity pattern in the North Atlantic population. This study addresses the interspecific concerns highlighted above as well as the intrapopulation structure of P. americanus from the Atlantic North, using the mitochondrial DNA Cytochrome Oxidase I gene and nuclear DNA microsatellite markers on a comprehensive sampling effort. The highly divergent gene pool from South Africa was characterized by the specific Mitochondrial DNA PamCOI.Saf haplotype. Its molecular composition and phylogenetic status were conspicuously intermediate between P. americanus and P. oxygeneios, which suggests its putative hybrid origin between those species. Microsatellite variation exhibited a high differentiation (24%) among four putative Polyprion spp. gene pools which contrasts with the large genetic homogeneity within the Atlantic North stock (FSC = 0.002). The significant migration rates inferred upon Bayesian algorithms suggest a longitudinal bi-directional connectivity pattern which strengthens the migratory hypothesis previously suggested on demographic data in the Atlantic North gene pool.