Mechanisms underlying speciation and adaptation processes in two closely related Drosophila virilis group species
Speciation is a slow process that proceeds through populations’ ecological divergence and the development of reproductive barriers. Populations living in the same area (sympatry) are susceptible to the disruptive effects of gene flow and recombination, which can slow down or prevent their divergence. Accordingly, natural selection may favour genetic mechanisms, like chromosomal inversions, which protect divergent loci from the homogenising effects of gene exchange and promote speciation. In this dissertation, I investigated the central aspects of speciation and adaptation using two closely related fly species, Drosophila montana and D. flavomontana. In the first chapter, I found the reproductive barriers between these species to be strong, but not complete. In D. flavomontana, the prezygotic barriers showed signs of reinforcement in sympatric populations, the type of barriers varying according to the length of species coexistence and/or species abundancies. The second chapter showed ecological isolation between D. montana and D. flavomontana to be enhanced by multiple environmental variables and to be largely based on species differences in cold tolerance. The third chapter suggested that chromosomal inversions had originated already before the species’ split, where they may have played an important role in the development of early reproductive barriers and/or ecological differences between local populations of the ancestral form. The last chapter, where I performed repeated interspecific backcrosses, indicated that the X chromosomal inversions, together with an incompatibility locus residing within them, effectively prevent gene flow from D. montana to D. flavomontana. Overall, this dissertation gives a comprehensive overview of the mechanisms underlying speciation and adaptation processes in these two species. It supports the existing speciation theories, but also brings up new perspectives, and shows that finding the final answers in speciation research is extremely challenging.
...
Publisher
Jyväskylän yliopistoISBN
978-951-39-8581-3ISSN Search the Publication Forum
2489-9003Contains publications
- Artikkeli I: Poikela, N., Kinnunen, J., Wurdack, M., Kauranen, H., Schmitt, T., Kankare, M., . . . , & Hoikkala, A. (2019). Strength of sexual and postmating prezygotic barriers varies between sympatric populations with different histories and species abundances. Evolution, 73 (6), 1182-1199. DOI: 10.1111/evo.13732. JYX: jyx.jyu.fi/handle/123456789/65424.
- Artikkeli II: Poikela, N., Tyukmaeva, V., Hoikkala, A. and Kankare, M. (2021). Multiple paths to cold tolerance: the role of environmental cues, morphological traits and the circadian clock gene vrille. Submitted manuscript. bioRxiv DOI: 10.1101/2020.04.20.050351.
- Artikkeli III: Poikela, N., Laetsch, D. R., Lohse, K. and Kankare, M. Ancestrally polymorphic chromosomal inversions as potential drivers of speciation. Manuscript.
- Artikkeli IV: Poikela, N., Laetsch, D. R., Kankare, M., Hoikkala, A. and Lohse, K. Experimental introgression in Drosophila species: asymmetric postzygotic isolation associated with chromosomal inversions and an incompatibility locus on the X chromosome. Manuscript.
Keywords
Metadata
Show full item recordCollections
- JYU Dissertations [846]
- Väitöskirjat [3559]
License
Related items
Showing items with similar title or keywords.
-
Adaptation and ecological speciation in seasonally varying environments at high latitudes : Drosophila virilis group
Hoikkala, Anneli; Poikela, Noora (Informa UK Limited, 2022)Living in high latitudes and altitudes sets specific requirements on species’ ability to forecast seasonal changes and to respond to them in an appropriate way. Adaptation into diverse environmental conditions can also ... -
Chromosomal Inversions and the Demography of Speciation in Drosophila montana and Drosophila flavomontana
Poikela, Noora; Laetsch, Dominik R; Hoikkala, Ville; Lohse, Konrad; Kankare, Maaria (Oxford University Press, 2024)Chromosomal inversions may play a central role in speciation given their ability to locally reduce recombination and therefore genetic exchange between diverging populations. We analyzed long- and short-read whole-genome ... -
Transposable elements in Drosophila montana from harsh cold environments
Tahami, Mohadeseh S.; Vargas-Chavez, Carlos; Poikela, Noora; Coronado-Zamora, Marta; González, Josefa; Kankare, Maaria (BioMed Central, 2024)Background Substantial discoveries during the past century have revealed that transposable elements (TEs) can play a crucial role in genome evolution by affecting gene expression and inducing genetic rearrangements, among ... -
Direct and correlated responses to bi-directional selection on pre-adult development time in Drosophila montana
Kauranen, Hannele; Kinnunen, Johanna; Hopkins, David; Hoikkala, Anneli (Elsevier Ltd., 2019)Selection experiments offer an efficient way to study the evolvability of traits that play an important role in insects’ reproduction and/or survival and to trace correlations and trade-offs between them. We have exercised ... -
Cold adaptation drives population genomic divergence in the ecological specialist, Drosophila montana
Wiberg, R. A. W.; Tyukmaeva, V.; Hoikkala, A.; Ritchie, M. G.; Kankare, M. (Wiley, 2021)Detecting signatures of ecological adaptation in comparative genomics is challenging, but analysing population samples with characterised geographic distributions, such as clinal variation, can help identify genes showing ...