Sex-linked genomic variation reveals reproductive skew and male-biased dispersal in polygynous sea lions

In the polygynous Galapagos sea lion (Otaria flavescens), genomic signatures indicate mild polygyny and a moderately elevated rate of male migration, especially across habitat boundaries.

• Why it matters: Sex-biased dispersal shapes gene flow, but quantifying it in nature is hard because sex-specific reproductive skew can confound genetic signals. Integrating multiple genomic compartments may help disentangle these processes.
• What they did: Using whole-genome resequencing, the study analyzed variation from mitochondria (MT), X and autosomes (X, AUT), and Y to infer mating system and test sex-specific migration across geographic and environmental boundaries in two polygynous sea lion species.
• The result: For Otaria flavescens, male-biased migration was moderately elevated and habitat-boundary–focused, while in the Steller sea lion (Eumetopias jubatus) male reproductive skew was substantially greater and male-biased migration more pronounced and less habitat-dependent.

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