Population structure of riverine and coastal dolphins Sotalia fluviatilis and Sotalia guianensis: PATTERNS of nuclear and mitochondrial diversity AND implications for conservation

Coastal and freshwater cetaceans are particularly vulnerable due to their proximity to human activity, localized distributions and small home ranges. These species include Sotalia guianensis, found in the Atlantic and Caribbean coastal areas of central and South America, and Sotalia fluviatilis, distributed in the Amazon River and tributaries. We investigated the population structure and genetic diversity of these two species by analyses of mtDNA control region and 8-10 microsatellite loci. MtDNA analyses revealed strong regional structuring for S. guianensis (i.e. Colombian Caribbean vs. Brazilian Coast, FST= 0.807, ΦST = 0.878, P <0.001) especially north and south of the Amazon River mouth. For S. fluviatilis, population structuring was detected between the western and eastern Amazon (i.e. Colombian Amazon vs. Brazilian Amazon, FST= 0.085, ΦST = 0.277, P <0.001). Haplotype and nucleotide diversity were higher for S. fluviatilis. Population differentiation was supported by ana...