Population genomics of the critically endangered Brazilian merganser

Abstract

The Brazilian merganser (Mergus octosetaceus) is one of the most endangered bird species in South America that comprises less than 250 mature individuals in the wild environments. This is a species extremely sensitive to environmental disturbances and restricted to few “pristine” freshwater habitats in Brazil, and it has been classified as Critically Endangered on the IUCN Red List since 1994. Understanding its current genetic diversity to promote in situ and ex situ management strategies was considered urgent for conservation of the remaining populations. To understand the evolutionary dynamics of remaining Brazilian merganser populations we have used "Genotyping by Sequencing" approach to characterize 923 SNPs in 31 individuals from all known areas of occurrence. The remaining populations of the Brazilian merganser present a low genetic diversity and high inbreeding levels likely due to recent population decline associated to habitat loss. Furthermore, it revealed a moderate level of genetic differentiation between all populations located in four separated areas of the highly threatened Cerrado biome. The results indicate that urgent actions for conservation of the species should be accompanied by a careful genetic monitoring to allow appropriate in situ and ex situ management to increase the long-term species survival in its natural environment.