Abstract
The South American sea lion, Otaria flavescens, is widely distributed along the Pacific and Atlantic coasts of South America. However, along the Brazilian coast, there are only two nonbreeding sites for the species (Refúgio de Vida Silvestre da Ilha dos Lobos and Refúgio de Vida Silvestre do Molhe Leste da Barra do Rio Grande), both in Southern Brazil. In this region, the species is continuously under the effect of anthropic activities, mainly those related to environmental contamination with organic and inorganic chemicals and fishery interactions. This paper reports, for the first time, the genetic diversity of O. flavescens found along the Southern Brazilian coast. A 287-bp fragment of the mitochondrial DNA control region (D-loop) was analyzed. Seven novel haplotypes were found in 56 individuals (OFA1-OFA7), with OFA1 being the most frequent (47.54%). Nucleotide diversity was moderate (π = 0.62%) and haplotype diversity was relatively low (67%). Furthermore, the median joining network analysis indicated that Brazilian haplotypes formed a reciprocal monophyletic clade when compared to the haplotypes from the Peruvian population on the Pacific coast. These two populations do not share haplotypes and may have become isolated some time back. Further genetic studies covering the entire species distribution are necessary to better understand the biological implications of the results reported here for the management and conservation of South American sea lions.
Highlights
The South American sea lion, Otaria flavescens (Shaw, 1800), is widely distributed along the coasts of South America, occurring from 6°S in the Pacific Ocean to 29°S in the Atlantic Ocean
The nucleotide diversity observed (0.006 ± 0.00067) is consistent with values reported by Wynen et al (8) for the same region of mtDNA of other sea lion species and populations, such as O. flavescens from the Pacific coast (π = 0.008), Eumetopias jubatus from Alaska (π = 0.004), and Phocarctus hookeri from New Zealand (π = 0.004)
The result observed for O. flavescens in the present study is within the range of nucleotide diversity described for other sea lion species
Summary
The South American sea lion, Otaria flavescens (Shaw, 1800), is widely distributed along the coasts of South America, occurring from 6°S in the Pacific Ocean to 29°S in the Atlantic Ocean. The main breeding colonies are located in Uruguay, Argentina, Falkland Islands (UK), Chile, and Peru (1). This is not a migratory species, seasonal movements occur when adult males, after the breeding season, move to the sea searching for food (2). The South American sea lion is one of the most frequent pinniped species in Brazil, occurring mainly during winter and spring. According to Rosas et al (3), specimens found along the Southern Brazilian coast are part of the breeding stock of Uruguayan rookeries. Some specimens from the Argentinian stock were recorded in Camboriú Beach (Santa Catarina, Southern Brazil) (Barreto AS, personal communication)
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