Molecular phylogeny of the South American sheldgeese with implications for conservation of Falkland Islands (Malvinas) and continental populations of the Ruddy-headed GooseChloephaga rubidicepsand Upland GooseC. picta

Abstract

SummarySheldgeese of the genusChloephagaare waterfowl (Anatidae) endemic to mainland South America and the Falkland Islands (Malvinas). Continental populations of three speciesC. picta,C. poliocephala, andC. rubidicepsbreed in Patagonia and Tierra del Fuego and migrate northwards to winter in central Argentina and Chile. These continental populations have declined by > 50% in the past 30 years due to direct hunting to control crop damage and by the introduction of the grey foxDusicyon griseusto their breeding grounds in Tierra del Fuego. The continental population ofC. rubidicepsis critically endangered, estimated to be < 1,000 individuals. While no historic population size estimates exist forC. rubidicepsin its wintering grounds, the breeding population in Tierra del Fuego was estimated to number several thousand individuals in the 1950s. In contrast, theC. rubidicepspopulation in the Falkland Islands (Malvinas) is non-migratory and stable with > 42,000 individuals, as is the Falkland Islands (Malvinas) population ofC. picta leucopterawith > 138,000 individuals. Here we use sequence data from the mitochondrial DNA control region to quantify genetic divergence between insular and continental populations of these two species of sheldgeese.Chloephaga rubidicepsandC. pictashowed significant intraspecific differentiation of 1.0% and 0.6%, respectively. In both cases, mainland and insular populations were reciprocally monophyletic and did not share mtDNA haplotypes. These results suggest that the insular and continental populations ofC. rubidicepsandC. pictaare genetically distinct and that female-mediated gene flow is restricted. We recommend a reevaluation of the threat category status of the continentalC. rubidicepspopulation, under IUCN guidelines. It is necessary to implement urgent actions for the conservation of this critically endangered population.