Evidence of strong population bottleneck in genetics of endangered Brazilian Merganser (Mergus octosetaceus)

The Brazilian Merganser is one of the rarest birds of South America with three known remnant populations in Brazil and only 250 individuals existing in the wild. Thus, evaluating the genetic variability within the remaining population is essential to its conservation. This study assessed genetic diversity of remnant populations by mtDNA (Dloop and cytb) and nDNA (MUSK 13 intron, five microsatellites) markers, giving support to management and conservation efforts. Seventy-one samples were collected during eight years from Chapada dos Veadeiros National Park (PNCV), Serra da Canastra National Park (PNSC), and Alto do Paranaíba region (APR). Cytochrome b, Dloop, and MUSK intron showed only one haplotype, indicating a loss of genetic variability for the Brazilian Merganser. The microsatellites confirmed low genetic variability (1–4 alleles). Despite the low variability observed, it was possible to infer minor differentiation between remnant populations, with PNCV locale being the most differentiated subgroup, due to its being isolated by greater distance from the others. Low genetic diversity observed in Brazilian Merganser, is expected to be found in Critically Endangered species, due to small population size, being result of high inbreeding rates, and gene drift effects. Thus, our genetic data have confirmed the extremely critical status of the Brazilian Merganser, making it necessary to create an immediate recovery program for their populations, and develop a management plan to integrate and preserve all remnant populations to avoid the species extinction.