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Evolution. 2019 Apr;73(4):750-761. doi: 10.1111/evo.13704. Epub 2019 Mar 6.

Hybridization and introgression during density-dependent range expansion: European wildcats as a case study.

Author information

1
Laboratory of Anthropology, Genetics and Peopling History, Department of Genetics and Evolution, Anthropology Unit, University of Geneva, Geneva, Switzerland.
2
Laboratory of Vertebrate Evolution, Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland.
3
Department of Zoology, University of Oxford, Oxford, United Kingdom.
4
Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
5
Institute of Genetics and Genomics in Geneva (IGE3), Geneva, Switzerland.

Abstract

Interbreeding between historically allopatric species with incomplete reproductive barriers may result when species expand their range. The genetic consequences of such hybridization depend critically on the dynamics of the range expansion. Hybridization models during range expansion have been developed but assume dispersal to be independent from neighboring population densities. However, organisms may disperse because they are attracted by conspecifics or because they prefer depopulated areas. Here, through spatially explicit simulations, we assess the effect of various density-dependent dispersal modes on the introgression between two species. We find huge introgression from the local species into the invasive one with all dispersal modes investigated, even when the hybridization rate is relatively low. This represents a general expectation for neutral genes even if the dispersal modes differ in colonization times and amount of introgression. Invasive individuals attracted by conspecifics need more time to colonize the whole area and are more introgressed by local genes, whereas the opposite is found for solitary individuals. We applied our approach to a recent expansion of European wildcats in the Jura Mountains and the hybridization with domestic cats. We show that the simulations explained better the observed level of introgression at nuclear, mtDNA, and Y chromosome markers, when using solitary dispersal for wildcats instead of random or gregarious dispersal, in accordance with ecological knowledge. Thus, use of density-dependent dispersal models increases the predictive power of the approach.

KEYWORDS:

Density-dependent dispersal; Felis silvestris; gene flow; invasive species; spatially explicit simulation

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