Experimental introgression in Drosophila: Asymmetric postzygotic isolation associated with chromosomal inversions and an incompatibility locus on the X chromosome.

Autor: Poikela N; Department of Biological and Environmental Science, University of Jyväskylä, Jyvaskyla, Finland., Laetsch DR; Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK., Kankare M; Department of Biological and Environmental Science, University of Jyväskylä, Jyvaskyla, Finland., Hoikkala A; Department of Biological and Environmental Science, University of Jyväskylä, Jyvaskyla, Finland., Lohse K; Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK.
Jazyk: angličtina
Zdroj: Molecular ecology [Mol Ecol] 2023 Feb; Vol. 32 (4), pp. 854-866. Date of Electronic Publication: 2022 Dec 22.
DOI: 10.1111/mec.16803
Abstrakt: Interspecific gene flow (introgression) is an important source of new genetic variation, but selection against it can reinforce reproductive barriers between interbreeding species. We used an experimental approach to trace the role of chromosomal inversions and incompatibility genes in preventing introgression between two partly sympatric Drosophila virilis group species, D. flavomontana and D. montana. We backcrossed F 1 hybrid females from a cross between D. flavomontana female and D. montana male with the males of the parental species for two generations and sequenced pools of parental strains and their reciprocal second generation backcross (BC 2 mon and BC 2 fla) females. Contrasting the observed amount of introgression (mean hybrid index, HI) in BC 2 female pools along the genome to simulations under different scenarios allowed us to identify chromosomal regions of restricted and increased introgression. We found no deviation from the HI expected under a neutral null model for any chromosome for the BC 2 mon pool, suggesting no evidence for genetic incompatibilities in backcrosses towards D. montana. In contrast, the BC 2 fla pool showed high variation in the observed HI between different chromosomes, and massive reduction of introgression on the X chromosome (large X-effect). This observation is compatible with reduced recombination combined with at least one dominant incompatibility locus residing within the X inversion(s). Overall, our study suggests that genetic incompatibilities arising within chromosomal inversions can play an important role in speciation.
(© 2022 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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