Environment-specific heterozygote deficiency and developmental instability in hybrid Mytilus

Abstract

The multiple discrete hybrid zones that characterize Mytilus blue mussels allow a novel, non-manipulative, examination of the selective pressures that create and maintain species. If endogenous genetic incompatibility is solely responsible for post-zygotic isolation, then individuals of a specified hybrid genotype are expected to show similar average fitness across environments. However, if hybrid fitness differs across environments, then exogenous selection is implicated, either via ecological selection or environment-specific expression of intrinsic genetic incompatibilities. Correspondence between developmental instability of hybrids and heterozygote deficiency, estimated in two M. trossulus×M. galloprovincialis hybrid zones on the coast of North America, indicates that environment-dependent selection against hybrids may contribute to reproductive isolation among Pacific Mytilus species.

Keywords:

• Developmental stability
• environment-dependent selection
• heterozygote deficiency
• Mytilus

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We thank J. Heath, M. Heath, T. Heath, V. Heath, C. Langdon and R. Burton, for collecting mussels. L. Rankin and S. Henry assisted in laboratory analysis. Fieldwork was supported by Yellow Island Aquaculture Limited, laboratory analysis by a Natural Sciences and Engineering Research Council of Canada (NSERC) research grant to DDH.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark