Projecting introgression from domestic cats into European wildcats in the Swiss Jura.

Claudio S Quilodrán,Mathias Currat,David W Macdonald,Juan I Montoya-Burgos,Beatrice Nussberger

doi:10.1111/eva.12968

Claudio S Quilodrán, Mathias Currat + Show 3 more

Open Access

https://doi.org/10.1111/eva.12968

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Abstract

Hybridization between wild and domesticated organisms is a worldwide conservation issue. In the Jura Mountains, threatened European wildcats (Felis silvestris) have been demographically spreading for approximately the last 50 years, but this recovery is coupled with hybridization with domestic cats (Felis catus). Here, we project the pattern of future introgression using different spatially explicit scenarios to model the interactions between the two species, including competition and different population sizes. We project the fast introgression of domestic cat genes into the wildcat population under all scenarios if hybridization is not severely restricted. If the current hybridization rate and population sizes remain unchanged, we expect the loss of genetic distinctiveness between wild and domestic cats at neutral nuclear, mitochondrial and Y chromosome markers in one hundred years. However, scenarios involving a competitive advantage for wildcats and a future increase in the wildcat population size project a slower increase in introgression. We recommend that future studies assess the fitness of these hybrids and better characterize their ecological niche and their ecological interactions with parental species to elucidate effective conservation measures.

Highlights

Interbreeding between evolutionarily significant units leading to hybridization is of growing concern in evolutionary and conservation biology
Building on previous studies that aimed to explain the current level of introgression between wildcats and domestic cats in the Swiss Jura (Nussberger et al, 2018; Q uilodrán et al, 2019), we use spatially explicit simulation to show here that the amount of introgression in wildcats is set to increase in the near future unless hybridization is drastically stopped
Even in the cases that are the most favourable to wildcats, including a competitive advantage for wildcats and a wildcat population size equal to (Nwild = Ndom) or twice that of domestic cats (Nwild > Ndom), the amount of introgression still increases over time but to a lesser extent

Summary

| INTRODUCTION

Interbreeding between evolutionarily significant units leading to hybridization is of growing concern in evolutionary and conservation biology. Our main aim in the current study is to project possible future amounts of introgression under different ecological conditions, including varying competition and population sizes, in order to explore the implications in terms of conservation of wildcats in the Swiss Jura. To achieve this objective, we characterize the interbreeding rate that best explains current patterns of introgression at nuclear, mitochondrial and Y chromosome markers by refining the previously developed genetic and demographic models. We use an approximate Bayesian computation method to better estimate the value of interbreeding, instead of the non-linear regression method used in the previous approach (Nussberger et al, 2018; Quilodrán et al, 2019)

| METHODS

Findings

| DISCUSSION