Data from: 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 analysis of the microsatellite loci (S. guianensis, northern South
America vs. southern South America FST= 0.275, Jost´s D = 0.476,
P<0.001; S. fluviatilis, western and eastern Amazon FST= 0.197,
Jost´s D = 0.364, P<0.001). Most estimated migration rates in both
species overlapped with zero, suggesting no measurable migration between
most of the sampling locations. However, for S. guianensis, there was
measurable migration in neighboring sampling locations. These results
indicate that the small home ranges of these species may act to restrict
gene flow between populations separated by relatively short distances,
increasing the risk of extirpation of some localized populations in the
future if existing threats are not minimized.