Range expansion as an explanation for introgression in European wildcats

Nussberger, Beatrice; Currat, Mathias; Quilodrán, Claudio S.; Ponta, N.; Keller, Lukas F.

doi:10.1016/j.biocon.2017.12.009

Cited by 35 publications

(64 citation statements)

References 43 publications

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“…While natural hybridization has been widely acknowledged as a powerful evolutionary force 6,7 , during last decades anthropogenic hybridization considerably contributed to threat the genomic integrity and survival of a number of taxa through the introgression of alien or domestic alleles in the gene pool of natural populations 3,11,12,15,41,42,59 . In particular, though some studies documented cases of beneficial introgression of domestic mutations in wild populations of North American wolves 27 and Alpine ibexes 28 , introgressive hybridization with www.nature.com/scientificreports www.nature.com/scientificreports/ domestic forms is globally recognized as a significant risk factor for the conservation of several wild taxa 14,24,28,[60][61][62] . However, though being essential to understand the real impact of the phenomenon and to design sound conservation strategies 16,23 , the identification of hybrids and their backcrosses remains far from trivial even in the genomic era [3][4][5]10,13 .…”

Section: Discussionmentioning

confidence: 99%

A standardized approach to empirically define reliable assignment thresholds and appropriate management categories in deeply introgressed populations

Caniglia

Galaverni

Velli

et al. 2020

Sci Rep

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Anthropogenic hybridization is recognized as a major threat to the long-term survival of natural populations. While identifying F1 hybrids might be simple, the detection of older admixed individuals is far from trivial and it is still debated whether they should be targets of management. Examples of anthropogenic hybridization have been described between wolves and domestic dogs, with numerous cases detected in the Italian wolf population. After selecting appropriate wild and domestic reference populations, we used empirical and simulated 39-autosomal microsatellite genotypes, Bayesian assignment and performance analyses to develop a workflow to detect different levels of wolf x dog admixture. Membership proportions to the wild cluster (q iw ) and performance indexes identified two qthresholds which allowed to efficiently classify the analysed genotypes into three assignment classes: pure (with no or negligible domestic ancestry), older admixed (with a marginal domestic ancestry) and recent admixed (with a clearly detectable domestic ancestry) animals. Based on their potential to spread domestic variants, such classes were used to define three corresponding management categories: operational pure, introgressed and operational hybrid individuals. Our multiple-criteria approach can help wildlife managers and decision makers in more efficiently targeting the available resources for the long-term conservation of species threatened by anthropogenic hybridization.Over the last decades, thanks to the growing availability of genetic and genomic data, hybridization has been increasingly studied for its evolutionary and conservational implications on the long-term survival of the involved taxa 1-5 . However, while natural hybridization between closely related taxa is frequently acknowledged as an evolutionary process providing novel adaptive gene assemblages 6,7 , anthropogenic hybridization (AH), mainly caused by intentional admixture, translocations, habitat modifications and climate changes 8-10 , is globally considered a serious conservation threat to the genetic integrity of local populations, which might be compromised by gene introgression from alien or domesticated species [11][12][13][14][15][16] . Thus, the consequences of such human-mediated process should be continuously monitored to evaluate their real effects on the viability of natural populations 5,17 .However, to date, even in the era of genomics 4,18 , the concept of hybrid itself is rather fleeting and, consequently, legal status and management of hybrids are often poorly regulated by national and international laws, hampering the conservation of endangered species 12,14,[19][20][21][22]

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Section: Discussionmentioning

confidence: 99%

A standardized approach to empirically define reliable assignment thresholds and appropriate management categories in deeply introgressed populations

Caniglia

Galaverni

Velli

et al. 2020

Sci Rep

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“…Under a spatially explicit simulation framework using SPLATCHE2, Nussberger et al. () were able to detect a recent range expansion of European wildcats in this area over the last 50 years, despite the fact that wildcats were considered to be almost extinct in 1962 when there was a change in protection policy. We thus extended the simulation framework used in Nussberger et al.…”

Section: Methodsmentioning

confidence: 99%

“…We thus extended the simulation framework used in Nussberger et al. () to investigate if the incorporation of density‐dependent dispersal may improves the accuracy of the model of wildcat expansion with hybridization to explain the observed evidence of introgression. Note that in this case, the expanding population is the indigenous one (wildcats) recovering its past habitat.…”

Section: Methodsmentioning

confidence: 99%

“…In a recent study, Nussberger et al. () used spatially explicit simulations to show that a range expansion of wildcats during the last 50 years, involving hybridization with domestic cats, explains better the observed patterns of introgression compare with other possible scenarios noninvolving wildcat spatial expansion. This example illustrates the fact that in contrast to the usual situation with an expanding invasive species and a native local species, the situation can be reversed in cases where threatened species recolonize formerly occupied habitat after successful conservation actions are taken.…”

mentioning

confidence: 99%

“…Here we extended this analysis by incorporating density‐dependent dispersal into the simulation framework designed by Nussberger et al. () to investigate (1) which spatial dispersal behavior explains best this recent range expansion and the associated genetic evidence of introgression; and (2) if modeling density‐dependent dispersal improves the accuracy of predictions of the extent of introgression under range expansion.…”

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

et al. 2019

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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.

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Wildcat population density in NE Portugal: A regional stronghold for a nationally threatened felid

et al. 2021

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Population density data on depleted and endangered wildlife species are essential to assure their effective management and, ultimately, conservation. The European wildcat is an elusive and threatened species inhabiting the Iberian Peninsula, with fragmented populations and living in low densities. We fitted spatial capture–recapture models on camera‐trap data, to provide the first estimate of wildcat density for Portugal and assess the most influential drivers determining it. The study was implemented in Montesinho Natural Park (NE Portugal), where we identified nine individuals, over a total effort of 3,477 trap‐nights. The mean density estimate was 0.032 ± 0.012 wildcat/km2, and density tended to increase with distance to humanized areas, often linked to lower human disturbance and domestic cat presence, with forest and herbaceous vegetation cover and with European rabbit abundance. Although, this density estimate is within the range of values estimated for protected areas elsewhere in the Iberian Peninsula, our estimates are low at the European level. When put in context, our results highlight that European wildcats may be living in low population densities across the Iberian Mediterranean biogeographic region. No phenotypic domestic or hybrid cats were detected, suggesting potentially low admixture rates between the two species, although genetic sampling would be required to corroborate this assertion. We provide evidence that Montesinho Natural Park may be a suitable area to host a healthy wildcat population, and thus be an important protected area in this species' conservation context.

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Range expansion as an explanation for introgression in European wildcats

Cited by 35 publications

References 43 publications

A standardized approach to empirically define reliable assignment thresholds and appropriate management categories in deeply introgressed populations

A standardized approach to empirically define reliable assignment thresholds and appropriate management categories in deeply introgressed populations

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

Wildcat population density in NE Portugal: A regional stronghold for a nationally threatened felid

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