Marine Biology

, Volume 131, Issue 3, pp 505–514

Assessment of natural selection in a hybrid population of mussels: evaluation of exogenous vs endogenous selection models

  • R. Wilhelm
  • T. J. Hilbish
Article

DOI: 10.1007/s002270050342

Cite this article as:
Wilhelm, R. & Hilbish, T. Marine Biology (1998) 131: 505. doi:10.1007/s002270050342

Abstract

We examined natural selection within a population of marine mussels, sampled in southwestern England in June 1991, containing a high frequency of hybrids between Mytilus edulis L. and M. galloprovincialis Lmk. This system is particularly tractable for the assessment of natural selection because hybridization is common and individual mussels can be aged, allowing changes in the frequency of hybrid genotypes among age classes to be determined. We show that strong viability selection occurs among hybrid genotypes which results in the virtual elimination of M. edulis–like genotypes from the population over a period of 3 years. Recombinant hybrid genotypes are intermediate in fitness, with M. edulis–like genotypes having a lower survival rate and M. galloprovincialis–like genotypes having a higher survival rate than genotypes of mixed ancestry. Since intermediate fitness for hybrid genotypes is inconsistent with endogenous selection models we conclude that the structure and position of this hybrid zone is probably generated by exogenous selection. This pattern of selection is a recurring feature of this hybrid population and likely occurs elsewhere in the hybrid zone. Selection against M. edulis–like genotypes appears to be offset by extensive immigration of larvae dispersed from pure populations of M. edulis.

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • R. Wilhelm
    • 1
  • T. J. Hilbish
    • 1
  1. 1.Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USAUS