Range-wide phylogeography of South American sea lion (Otaria flavescens) reveals an extremely ancient female philopatry and an asymmetric male gene flow between Pacific and Atlantic oceans

DE OLIVEIRA, LARISSA ROSA; GEHARA, MARCELO C. M.; FRAGA LÚCIA D.; LOPEZ F; TUNEZ J. I.; CASSINI, MARCELO H.; MAJLUF, PATRICIA; CARDENAS ALAYSA S; PAVÉS, HÉCTOR J.; CRESPO ENRIQUE ALBERTO; GARCÍA NÉSTOR ANÍBAL; LOIZAGA DE CASTRO, ROCÍO; HOELZEL, A. RUS; MARITZA SEPÚLVEDA; OLAVARRÍA, CARLOS; VALIATI, VICTOR HUGO; QUIÑONES, RENATO; PEREZ ALVAREZ M. J.; OTT, PAULO HENRIQUE; BONATTO, SANDRO L.

Valparaiso

Congreso; 17° Reunión de Trabajo de Especialistas en Mamíferos Acuáticos de América del Sur y XI Congreso de la Solamac; 2016

SOLAMAC y Centro de Investigación y Gestión de Recursos Naturales (CIGREN) de la Universidad de Valparaíso

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 lions along its distribution by analyses of mitochondrial DNA (mtDNA) and 10 nuclear microsatellites loci. In this context, we analyzed 147 sequences of mtDNA control region and genotyped 111 individualsof 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 (>1 million years), suggesting a long period of no 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 suggestedsome 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 shown 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.