Estuarine habitats protect hybrid mussels from selection

The marine mussels, Mytilus edulis and Mytilus galloprovincialis, form an extensive hybrid zone in Europe where F 2 hybrids and mussels of mixed genetic ancestry are often locally abundant. Hybrid zones are maintained by the interplay of dispersal and selection on hybrid genotypes but there has been...

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Bibliographic Details
Published in:Journal of experimental marine biology and ecology 2003-08, Vol.292 (2), p.177-186
Main Authors: Hilbish, T.J., Timmons, J., Agrawal, V., Schneider, K.R., Gilg, M.R.
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Autoecology
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Genetics of eukaryotes. Biological and molecular evolution
Habitat
Invertebrata
Mussel
Mytilus edulis
Mytilus galloprovincialis
Population genetics, reproduction patterns
Protozoa. Invertebrata
Selection
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Summary:The marine mussels, Mytilus edulis and Mytilus galloprovincialis, form an extensive hybrid zone in Europe where F 2 hybrids and mussels of mixed genetic ancestry are often locally abundant. Hybrid zones are maintained by the interplay of dispersal and selection on hybrid genotypes but there has been vigorous debate on the form of selection that may occur in these systems. Tension zone models argue that selection is against hybrids because of developmental misregulation and is independent of the external environment. Exogenous selection models argue that selection is habitat-dependent and the structure of the hybrid zone is due to the distribution of habitat patches that vary in selection intensity. We test this prediction by comparing the genetic structure of mussel populations in open-coast habitats, where selection on hybrids is strong, to those within two independent estuaries. We show that mussels within these estuaries are protected from selection and thus selection is strongly dependent on habitat, which supports the exogenous selection hypothesis. Hybrid mussel populations on the open-coast experience strong selection against M. edulis-like genotypes, which has been postulated to be the result of differential dislodgment by waves. This hypothesis is supported by our results since mussels within sheltered habitats are protected from selection. There was, despite previous suggestions, no evidence of selection in favor of M. edulis-like mussels within either estuary.
ISSN:0022-0981
1879-1697
DOI:10.1016/S0022-0981(03)00161-8