Koch, Eva L.; Ravinet, Mark; Westram, Anja MISTA ; Johannesson, Kerstin; Butlin, Roger K.
Chromosomal inversions have been shown to play a major role in a local adaptation by suppressing recombination between alternative arrangements and maintaining beneficial allele combinations. However, so far, their importance relative to the remaining genome remains largely unknown. Understanding the genetic architecture of adaptation requires better estimates of how loci of different effect sizes contribute to phenotypic variation. Here, we used three Swedish islands where the marine snail Littorina saxatilis has repeatedly evolved into two distinct ecotypes along a habitat transition. We estimated the contribution of inversion polymorphisms to phenotypic divergence while controlling for polygenic effects in the remaining genome using a quantitative genetics framework. We confirmed the importance of inversions but showed that contributions of loci outside inversions are of similar magnitude, with variable proportions dependent on the trait and the population. Some inversions showed consistent effects across all sites, whereas others exhibited site-specific effects, indicating that the genomic basis for replicated phenotypic divergence is only partly shared. The contributions of sexual dimorphism as well as environmental factors to phenotypic variation were significant but minor compared to inversions and polygenic background. Overall, this integrated approach provides insight into the multiple mechanisms contributing to parallel phenotypic divergence.
We thank everyone who helped with fieldwork, snail processing, and DNA extractions, particularly Laura Brettell, Mårten Duvetorp, Juan Galindo, Anne-Lise Liabot, Irena Senčić, and Zuzanna Zagrodzka. We also thank Rui Faria and Jenny Larsson for their contributions, with inversions and shell shape respectively. KJ was funded by the Swedish research council Vetenskapsrådet, grant number 2017-03798. R.K.B. and E.K. were funded by the European Research Council (ERC-2015-AdG-693030-BARRIERS). R.K.B. was also funded by the Natural Environment Research Council and the Swedish Research Council Vetenskapsrådet.
Koch EL, Ravinet M, Westram AM, Johannesson K, Butlin RK. Genetic architecture of repeated phenotypic divergence in Littorina saxatilis evolution. Evolution. 2022;76(10):2332-2346. doi:10.1111/evo.14602
Koch, E. L., Ravinet, M., Westram, A. M., Johannesson, K., & Butlin, R. K. (2022). Genetic architecture of repeated phenotypic divergence in Littorina saxatilis evolution. Evolution. Wiley. https://doi.org/10.1111/evo.14602
Koch, Eva L., Mark Ravinet, Anja M Westram, Kerstin Johannesson, and Roger K. Butlin. “Genetic Architecture of Repeated Phenotypic Divergence in Littorina Saxatilis Evolution.” Evolution. Wiley, 2022. https://doi.org/10.1111/evo.14602.
E. L. Koch, M. Ravinet, A. M. Westram, K. Johannesson, and R. K. Butlin, “Genetic architecture of repeated phenotypic divergence in Littorina saxatilis evolution,” Evolution, vol. 76, no. 10. Wiley, pp. 2332–2346, 2022.
Koch EL, Ravinet M, Westram AM, Johannesson K, Butlin RK. 2022. Genetic architecture of repeated phenotypic divergence in Littorina saxatilis evolution. Evolution. 76(10), 2332–2346.
Koch, Eva L., et al. “Genetic Architecture of Repeated Phenotypic Divergence in Littorina Saxatilis Evolution.” Evolution, vol. 76, no. 10, Wiley, 2022, pp. 2332–46, doi:10.1111/evo.14602.
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