Deep genetic subdivision within a continuously distributed and highly vagile marine mammal, the Steller's sea lion (Eumetopias jubatus)

The Steller's sea lion Eumetopias jubatus is an endangered marine mammal that has experienced dramatic population declines over much of its range during the past five decades. Studies using mitochondrial DNA (mtDNA) have shown that an apparently continuous population includes a strong division,...

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Bibliographic Details
Published in:Molecular ecology 2006-09, Vol.15 (10), p.2821-2832
Main Authors: HOFFMAN, J.I, MATSON, C.W, AMOS, W, LOUGHLIN, T.R, BICKHAM, J.W
Format: Article
Language:English
Subjects:
Animal populations
Animals
Bayes Theorem
Cluster Analysis
conservation genetics
Endangered & extinct species
Eumetopias jubatus
Female
gene flow
Genetic diversity
genetic structure
Genotype & phenotype
Geography
Heterozygote
isolation by distance
Linkage Disequilibrium - genetics
Marine
Marine mammals
microsatellite
Microsatellite Repeats - genetics
Mitochondrial DNA
Phylogeny
phylogeography
pinniped
Population Dynamics
Sampling Studies
Sea Lions - genetics
Sea Lions - physiology
stocks
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Summary:The Steller's sea lion Eumetopias jubatus is an endangered marine mammal that has experienced dramatic population declines over much of its range during the past five decades. Studies using mitochondrial DNA (mtDNA) have shown that an apparently continuous population includes a strong division, yielding two discrete stocks, western and eastern. Based on a weaker split within the western stock, a third Asian stock has also been defined. While these findings indicate strong female philopatry, a recent study using nuclear microsatellite markers found little evidence of any genetic structure, implying extensive paternal gene flow. However, this result was at odds with mark-recapture data, and both sample sizes and genetic resolution were limited. To address these concerns, we increased analytical power by genotyping over 700 individuals from across the species' range at 13 highly polymorphic microsatellite loci. We found a clear phylogenetic break between populations of the eastern stock and those of the western and Asian stocks. However, our data provide little support for the classification of a separate Asian stock. Our findings show that mtDNA structuring is not due simply to female philopatry, but instead reflects a genuine discontinuity within the range, with implications for both the phylogeography and conservation of this important marine mammal.
ISSN:0962-1083
1365-294X
DOI:10.1111/j.1365-294X.2006.02991.x