Speciation as a positive feedback loop between postzygotic and prezygotic barriers to gene flow

Speciation is intimately associated with the evolution of sex-and-reproduction-related traits, including those affecting hybrid incompatibility (postzygotic isolation) and species recognition (prezygotic isolation). Genes controlling such traits are not randomly distributed in the genome but are par...

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Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 2003-07, Vol.270 (1523), p.1473-1479
Main Authors: Servedio, Maria R., Sætre, Glenn-Peter
Format: Article
Language:English
Subjects:
Adaptation, Biological
Alleles
Animals
Biological Evolution
Computer Simulation
Evolution
Evolutionary genetics
Gene Flow
Genes
Genetic Linkage
Genetic loci
Genotypes
Haldane's Rule
Hitchhiking
Hybridity
Hybridization, Genetic
Infertility - genetics
Mating behavior
Models, Genetic
Reinforcement
Sex Chromosome
Sex Chromosomes
Sex Linkage
Sexual Behavior, Animal
Speciation
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Summary:Speciation is intimately associated with the evolution of sex-and-reproduction-related traits, including those affecting hybrid incompatibility (postzygotic isolation) and species recognition (prezygotic isolation). Genes controlling such traits are not randomly distributed in the genome but are particularly abundant on the sex chromosomes. However, the evolutionary consequences of the sex linkage of genes involved in speciation have been little explored. Here, we present simulations of a continent-island diploid model that examines the effects of reduced recombination using both autosomal and sex-linked inheritance. We show first that linkage between genes affecting postzygotic and prezygotic isolation leads to a positive feedback loop in which both are strengthened. As species recognition evolves, genes causing hybrid incompatibility will hitchhike along with those improving premating isolation, leading to stronger hybrid incompatibility and thus increased pressure for further preference divergence. Second, we show that this loop effect is generally enhanced by sex linkage, because recombination is eliminated in the heterogametic sex, leading to tighter effective linkage between the two classes of genes and because natural selection is more efficient at sex-linked loci, as recessive alleles are not masked by dominance in the heterogametic sex. Accordingly, hitchhiking can be important in promoting speciation and can also lead to increased postzygotic isolation through adaptive evolution.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.2003.2391