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Lower reproductive success in hybrid fur seal males indicates fitness costs to hybridization

Lancaster, Melanie L., Bradshaw, Corey J. A., Goldsworthy, Simon D. and Sunnucks, Paul (2007). Lower reproductive success in hybrid fur seal males indicates fitness costs to hybridization. Molecular Ecology,16(15):3187-3197.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 18 times in Scopus Article | Citations

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IRMA ID A00003xPUB53
Title Lower reproductive success in hybrid fur seal males indicates fitness costs to hybridization
Author Lancaster, Melanie L.
Bradshaw, Corey J. A.
Goldsworthy, Simon D.
Sunnucks, Paul
Journal Name Molecular Ecology
Publication Date 2007
Volume Number 16
Issue Number 15
ISSN 0962-1083   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-34447642903
Start Page 3187
End Page 3197
Total Pages 11
Place of Publication Oxford, England
Publisher Blackwell Publishing
HERDC Category C1 - Journal Article (DEST)
Abstract Hybridization among organisms can potentially contribute to the processes of evolution, but this depends on the fitness of hybrids relative to parental species. A small, recently formed population of fur seals on subantarctic Macquarie Island contains a high proportion of hybrids (17-30%) derived from combinations of three parental species: Antarctic, subantarctic and New Zealand fur seals. Mitochondrial control-region data (restriction fragment length polymorphisms) and nine microsatellites were used to determine the species composition of breeding adults, and hybrid male fitness was measured by comparing reproductive success (number of genetically inferred paternities) of hybrid and pure-species territory males over 6 years. No correlations were found between male reproductive success and three genetic measures of outbreeding, but this may be due to a relatively small number of dominant males analysed. Territory males fathered 63% of pups, but hybrid males had lower reproductive success than pure-species males despite having the same ability to hold territories. A greater proportion of females in hybrid male territories conceived extra-territorially than those in territories of pure-species males, and most (70 of 82) mated with conspecifics. This suggests the presence of reproductive isolating mechanisms that promote positive assortative mating and reduce the production of hybrid offspring. Although we found no evidence for male sterility in the population, mechanisms that reduce lifetime reproductive success may act to decrease the frequency of hybrids. Our study has identified a disadvantage of hybridization - reduced reproductive success of hybrid sons - that may be contributing to the persistence of pure lineages at Macquarie Island and the temporal decline in hybridization observed there.
Keywords Arctocephalus
hybrid fitness
mean d(2)
reproductive isolation
grey seal
parental relatedness
multimodel inference
paternity inference
haldanes rule
red deer
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