Publication Date:
2012-06-14
Description:
Background: When genetic structure is identified using mitochondrial DNA (mtDNA), but no structure isidentified using biparentally-inherited nuclear DNA, the discordance is often attributed todifferences in dispersal potential between the sexes. Results: We sampled the intertidal rocky shore mussel Perna perna in a South African bay and alongthe nearby open coast, and sequenced maternally-inherited mtDNA (there is no evidence forpaternally-inherited mtDNA in this species) and a biparentally-inherited marker. By treatingmales and females as different populations, we identified significant genetic structure on thebasis of mtDNA data in the females only. Conclusions: This is the first study to report sex-specific differences in genetic structure based onmatrilineally-inherited mtDNA in a passively dispersing species that lacks social structure orsexual dimorphism. The observed pattern most likely stems from females being morevulnerable to selection in habitats from which they did not originate, which also manifestsitself in a male-biased sex ratio. Our results have three important implications for theinterpretation of population genetic data. First, even when mtDNA is inherited exclusively inthe female line, it also contains information about males. For that reason, using it to identifysex-specific differences in genetic structure by contrasting it with biparentally-inheritedmarkers is problematic. Second, the fact that sex-specific differences were found in apassively dispersing species in which sex-biased dispersal is unlikely highlights the fact thatsignificant genetic structure is not necessarily a function of low dispersal potential or physicalbarriers. Third, even though mtDNA is typically used to study historical demographicprocesses, it also contains information about contemporary processes. Higher survival ratesof males in non-native habitats can erase the genetic structure present in their mothers withina single generation.
Electronic ISSN:
1471-2156
Topics:
Biology
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