Perini, Samuel; Rafajlović, Marina; Westram, Anja MIST Austria ; Johannesson, Kerstin; Butlin, Roger K.
When divergent populations are connected by gene flow, the establishment of complete reproductive isolation usually requires the joint action of multiple barrier effects. One example where multiple barrier effects are coupled consists of a single trait that is under divergent natural selection and also mediates assortative mating. Such multiple‐effect traits can strongly reduce gene flow. However, there are few cases where patterns of assortative mating have been described quantitatively and their impact on gene flow has been determined. Two ecotypes of the coastal marine snail, Littorina saxatilis , occur in North Atlantic rocky‐shore habitats dominated by either crab predation or wave action. There is evidence for divergent natural selection acting on size, and size‐assortative mating has previously been documented. Here, we analyze the mating pattern in L. saxatilis with respect to size in intensively sampled transects across boundaries between the habitats. We show that the mating pattern is mostly conserved between ecotypes and that it generates both assortment and directional sexual selection for small male size. Using simulations, we show that the mating pattern can contribute to reproductive isolation between ecotypes but the barrier to gene flow is likely strengthened more by sexual selection than by assortment.
We are very grateful to I. Sencic, L. Brettell, A.‐L. Liabot, J. Galindo, M. Ravinet, and A. Butlin for their help with field sampling and mating experiments. This work was funded by the Natural Environment Research Council, European Research Council and Swedish Research Council VR and we are also very grateful for the support of the Linnaeus Centre for Marine Evolutionary Biology at the University of Gothenburg. The simulations were performed on resources at Chalmers Centre for Computational Science and Engineering (C3SE) provided by the Swedish National Infrastructure for Computing (SNIC). AMW was funded by the European Union's Horizon 2020 research and innovation program under Marie Skłodowska‐Curie grant agreement no. 797747.
Perini S, Rafajlović M, Westram AM, Johannesson K, Butlin RK. Assortative mating, sexual selection, and their consequences for gene flow in Littorina. Evolution. 2020;74(7):1482-1497. doi:10.1111/evo.14027
Perini, S., Rafajlović, M., Westram, A. M., Johannesson, K., & Butlin, R. K. (2020). Assortative mating, sexual selection, and their consequences for gene flow in Littorina. Evolution. Wiley. https://doi.org/10.1111/evo.14027
Perini, Samuel, Marina Rafajlović, Anja M Westram, Kerstin Johannesson, and Roger K. Butlin. “Assortative Mating, Sexual Selection, and Their Consequences for Gene Flow in Littorina.” Evolution. Wiley, 2020. https://doi.org/10.1111/evo.14027.
S. Perini, M. Rafajlović, A. M. Westram, K. Johannesson, and R. K. Butlin, “Assortative mating, sexual selection, and their consequences for gene flow in Littorina,” Evolution, vol. 74, no. 7. Wiley, pp. 1482–1497, 2020.
Perini S, Rafajlović M, Westram AM, Johannesson K, Butlin RK. 2020. Assortative mating, sexual selection, and their consequences for gene flow in Littorina. Evolution. 74(7), 1482–1497.
Perini, Samuel, et al. “Assortative Mating, Sexual Selection, and Their Consequences for Gene Flow in Littorina.” Evolution, vol. 74, no. 7, Wiley, 2020, pp. 1482–97, doi:10.1111/evo.14027.
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