Patterns of male sterility in a grasshopper hybrid zone imply accumulation of hybrid incompatibilities without selection

David Michael Shuker, K Underwood, TM King, RK Butlin

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)

Abstract

It is now widely accepted that post-zygotic reproductive isolation is the result of negative epistatic interactions between derived alleles fixed independently at different loci in diverging populations (the Dobzhansky-Muller model). What is less clear is the nature of the loci involved and whether the derived alleles increase in frequency through genetic drift, or as a result of natural or sexual selection. If incompatible alleles are fixed by selection, transient polymorphisms will be rare and clines for these alleles will be steep where divergent populations meet. If they evolve by drift, populations are expected to harbour substantial genetic variation in compatibility and alleles will introgress across hybrid zones once they recombine onto a genetic background with which they are compatible. Here we show that variation in male sterility in a naturally occurring Chorthippus parallelus grasshopper hybrid zone conforms to the neutral expectations. Asymmetrical clines for male sterility have long tails of introgression and populations distant from the zone centre show significant genetic variation for compatibility. Our data contrast with recent observations on 'speciation genes' that have diverged as a result of strong natural selection.

Original languageEnglish
Pages (from-to)2491-2497
Number of pages7
JournalProceedings of the Royal Society of London Series B: Biological Sciences
Volume272
Issue number1580
DOIs
Publication statusPublished - 7 Dec 2005

Keywords

  • Dobzhansky-Muller incompatibilities
  • epistasis
  • hybrid zone
  • speciation
  • hybrid male sterility
  • CHORTHIPPUS-PARALLELUS-ERYTHROPUS
  • POSTMATING REPRODUCTIVE ISOLATION
  • POSTZYGOTIC ISOLATION
  • HALDANE RULE
  • TRIBOLIUM-CASTANEUM
  • TESTING HYPOTHESES
  • T-FREEMANI
  • ORTHOPTERA
  • SPECIATION
  • DROSOPHILA

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