A1 Journal article (refereed)
Experimental introgression in Drosophila : asymmetric postzygotic isolation associated with chromosomal inversions and an incompatibility locus on the X chromosome (2023)

Poikela, N., Laetsch, D. R., Kankare, M., Hoikkala, A., & Lohse, K. (2023). Experimental introgression in Drosophila : asymmetric postzygotic isolation associated with chromosomal inversions and an incompatibility locus on the X chromosome. Molecular Ecology, 32(4), 854-866. https://doi.org/10.1111/mec.16803

JYU authors or editors

Publication details

All authors or editors: Poikela, N.; Laetsch, D. R.; Kankare, M.; Hoikkala, A.; Lohse, K.

Journal or series: Molecular Ecology

ISSN: 0962-1083

eISSN: 1365-294X

Publication year: 2023

Publication date: 02/12/2022

Volume: 32

Issue number: 4

Pages range: 854-866

Publisher: Wiley-Blackwell

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1111/mec.16803

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/84341

Web address of parallel published publication (pre-print): https://www.biorxiv.org/content/10.1101/2022.07.07.499141v1

Abstract

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 F1 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 2nd generation backcross (BC2mon and BC2fla) females. Contrasting the observed amount of introgression (mean hybrid index, HI) in BC2 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 BC2mon pool, suggesting no evidence for genetic incompatibilities in backcrosses towards D. montana. In contrast, the BC2fla 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.

Keywords: hybrids (biology); genetics; genome; genes; chromosomes; population genetics

Free keywords: chromosomal inversions; experimental evolution; genetic incompatibilities; hybridization; introgression; X-effect

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Ministry reporting: Yes

VIRTA submission year: 2023

JUFO rating: 3