Ancient female philopatry, asymmetric male gene flow, and synchronous population expansion support the influence of climatic oscillations on the evolution of South American sea lion (Otaria flavescens)

The South American sea lion (Otaria flavescens) is widely distributed along the southern Atlantic and Pacific coasts of South America with a history of significant commercial exploitation. We aimed to evaluate the population genetic structure and the evolutionary history of South American sea lion along its distribution by analyses of mitochondrial DNA (mtDNA) and 10 nuclear microsatellites loci. We analyzed 147 sequences of mtDNA control region and genotyped 111 individuals of South American sea lion for 10 microsatellite loci, representing six populations (Peru, Northern Chile, Southern Chile, Uruguay (Brazil), Argentina and Falkland (Malvinas) Islands) and covering the entire distribution of the species. The mtDNA phylogeny shows that haplotypes from the two oceans comprise two very divergent clades as observed in previous studies, suggesting a long period (>1 million years) of low inter-oceanic female gene flow. Bayesian analysis of bi-parental genetic diversity supports significant (but less pronounced than mitochondrial) genetic structure between Pacific and Atlantic populations, although also suggested some inter-oceanic gene flow mediated by males. Higher male migration rates were found in the intra-oceanic population comparisons, supporting very high female philopatry in the species. Demographic analyses showed that populations from both oceans went through a large population expansion ~10,000 years ago, suggesting a very similar influence of historical environmental factors, such as the last glacial cycle, on both regions. Our results support the proposition that the Pacific and Atlantic populations of the South American sea lion should be considered distinct evolutionarily significant units, with at least two managements units in each ocean.Fil: Rosa de Oliveira, Larissa. Universidade do Vale do Rio dos Sinos; Brasil. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; BrasilFil: Gehara, Marcelo C. M.. American Museum Of Natural History; Estados Unidos. Pontificia Universidade Católica do Rio Grande do Sul; BrasilFil: Fraga, Lúcia D.. Universidade do Vale do Rio dos Sinos; Brasil. Pontificia Universidade Católica do Rio Grande do Sul; BrasilFil: Lopes, Fernando. Universidade do Vale do Rio dos Sinos; Brasil. Pontificia Universidade Católica do Rio Grande do Sul; BrasilFil: Tunez, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Luján; ArgentinaFil: Cassini, Marcelo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina. Universidad Nacional de Luján; ArgentinaFil: Majluf, Patricia. Universidad Peruana Cayetano Heredia; PerúFil: Cárdenas Alayza, Susana. Universidad Peruana Cayetano Heredia; PerúFil: Pavés, Héctor J.. Universidad Santo Tomas; ChileFil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Garcia, Nestor Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Loizaga de Castro, Rocio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Hoelzel, A. Rus. University Of Durham; Reino UnidoFil: Sepúlveda, Maritza. Facultad de Ciencias, Universidad de Valparaíso; Chile. Millenium Nucleus of Invasive Salmonids; ChileFil: Olavarría, Carlos. Centro de Estudios Avanzados en Zonas Aridas; ChileFil: Valiati, Victor Hugo. Universidade do Vale do Rio dos Sinos; BrasilFil: Quiñones, Renato. Universidad de Concepción; ChileFil: Pérez Alvarez, Maria Jose. Universidad de Chile; ChileFil: Ott, Paulo Henrique. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidade Estadual do Rio Grande do Sul; BrasilFil: Bonatto, Sandro Luis. Pontificia Universidade Católica do Rio Grande do Sul; Brasi