The presence of two distinct mitochondrial lineages in the bottlenose dolphin (Tursiops truncatus) in Puerto Rico and their affinities with previously reported lineages

Abstract

Sound management of coastal resources is based on science-based decisions. Bottlenose dolphins are found around Puerto Rico; however, limited information exists on the ecology, behavior, sex ratio, distribution patterns, and population structure presenting, challenges in managing the bottlenose dolphin as defined in the Marine Mammal Protection Act of 1972. We sequenced the mitochondrial control region (mtDNA-CR) of 27 live and 11 stranded dolphins from Puerto Rico, five stranded dolphins from Guadeloupe and included sequences from the North Atlantic and the Pacific Ocean. Our genetic data from the new samples indicates the presence of distinct genetic lineages (inshore—represented by coastal individuals) and worldwide-distributed form (represented by both coastal and offshore individuals) in Puerto Rico. DNA divergence between inshore/coastal and offshore haplotypes ranged from 4.34 to 6.58%. All haplotypes from Puerto Rico have been previously reported from the Caribbean and North Atlantic. Genetic analysis yielded a complex population structure without a clear geographic signal; an expected result from a highly mobile marine mammal. A clade consisting exclusively of coastal dolphins of the Caribbean and the western North Atlantic was recovered. Offshore haplotypes from the eastern and western North Atlantic were generally clustered with offshore haplotypes of the Caribbean. Coastal and offshore haplotypes from the Pacific differed from those from the Atlantic. When we partitioned the data by form (coastal vs. offshore) and ocean (Atlantic vs. Pacific), we detected significant population differentiation (F_ST = 0.4089), indicating limited gene flow between forms and across oceans.