Phylogeography and genetic diversity of pantropical spotted dolphin (Stenella attenuata) and other delphinids in the Caribbean

Abstract

The pantropical spotted dolphin (Stenella attenuata) is a cetacean species with a broad distribution encompassing tropical waters. However, this species can exhibit geographic variations in coloration and morphology. Such is the case for the subspecies present in the Eastern Pacific, S. attenuata graffmani, with higher proportions of spots compared to populations in territories such as Hawaii. On the other hand, S. attenuata exhibits considerable abundance compared to other cetaceans in Caribbean regions such as the Gulf of Mexico and in Eastern Pacific regions. Recent studies suggest that this species can have genetic structure associated to geographic location. Here we assessed the population structure and genetic diversity of this species in the Caribbean, comparing samples originating from different geographic locations, including Guadeloupe (French West Indies), Saint Vincent and the Grenadines (SVG), Curaçao, Dominican Republic, Bahamas, Belize, Florida (USS) and Gulf of Mexico. Sequences from the mitochondrial gene control region (CR) and 13 microsatellites were used to test the genetic population structure of individuals sampled across the region were compared with other sequences obtained from the genetic database GenBank. Significant genetic differentiation was determined between spotted dolphins from our main sampling locations, particularly SVG, Guadeloupe and other parts of the Western Atlantic. These results also show that the populations from SVG (where dolphins are locally hunted) present significant isolation from other populations sampled in the Caribbean. Also, individuals from Guadeloupe exhibit connectivity with populations from other islands in the Caribbean and the Western Atlantic. The results obtained in this study can provide new insights for the understanding of population dynamics of the pantropical spotted dolphin and can be used as a baseline for local conservation initiatives in the Caribbean.