Changes in the demographic trends of Pink river dolphins (Inia) at the microgeographical level in peruvian and bolivian rivers and within the upper amazon: Microsatellites and mtDNA analyses and insights into Inia's origin

More than 200 pink river dolphins (Inia geoffrensis and Inia boliviensis) were sampled in diverse rivers of Colombia, Peru, Brazil and Bolivia. Ten microsatellites and 400 bp of the mitochondrial control region (D-loop) gene were analyzed with special emphasis on three Peruvian rivers (Ucayali, Marañon and Napo-Curaray) and the Bolivian Mamoré River (and tributaries). Of the different evolutionary demographic tests applied to the microsatellite and mtDNA data, the tests of Kimmel et al., (2008) and Zhivotovsky et al., (2000) provided the most insights about the demographic history of the pink river dolphin. These tests showed that initial bottlenecks occurred prior to very recent population expansions in the diverse areas studied. Two tests (Zhivotovsky and Garza & Williamson) revealed a very strong bottleneck in the origin of the Bolivian population and not during its population expansion. Together, the microsatellite and mtDNA, analyses revealed a strong population expansion for the overall upper Amazon sample and supported that the population expansion and colonization of Inia throughout the Amazon, Orinoco and Beni-Mamore´ basins occurred in the last 200,000 years agoand in the majority of cases between 4,000-50,000 years ago) and not several millions of years ago as was claimed by other authors. Furthermore, the original population was the Amazon one, and not the Bolivian population as has been previously defended by several authors, such as Grabert (1984 a, b, c), Pilleri & Ghir (1977, 1980) and Pilleri et al. (1982).