Evol Ecol Res 12: 523-544 (2010)     Full PDF if your library subscribes.

Recombination and epistasis facilitate introgressive hybridization across reproductively isolated populations: a gamete-based simulation

Yoshinari Tanaka

Center for Environmental Risk, National Institute for Environmental Studies, Tsukuba, Japan

Correspondence: Y. Tanaka, Center for Environmental Risk, National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-8506, Japan.
e-mail: ytanaka@nies.go.jp


Questions: Why can invasive species sometimes genetically contaminate closely related indigenous species by introgressive hybridization, resisting the post-zygotic isolating mechanism? How do recombination rates and epistasis among incompatibility genes, and the number of loci affect the introgression?

Features of models: The individual-based model and gamete-based model, which tracks changes in the number of invasive genes per gamete due to selection and recombination by assuming random arrangement of genes within gamete.

Range of key variables: The recombination rate between adjacent loci ranges from 0 to 0.4. The epistatic effect between loci is measured by the exponent of the geometric function of heterozygosities representing individual fitness. It ranges from 1 (additive) to 4 (strong epistasis). The number of loci is set to 2–10 for the gamete-based model.

Conclusions: Provided that the number of loci is not very small and the fitness of the F1 hybrid is not extremely low, complete genetic replacement by introgressive hybridization is accelerated by an increase in rates of total recombination across all loci and by the epistatic fitness effect among incompatibility loci.

Keywords: Dobzhansky-Mueller model, epistasis, gamete-based model, introgressive hybridization, multi-locus underdominance, post-zygotic isolation.

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