Genetic analysis shows low levels of hybridization between African wildcats (Felis silvestris lybica) and domestic cats (F. s. catus) in South Africa

Hybridization between domestic and wild animals is a major concern for biodiversity conservation, and as habitats become increasingly fragmented, conserving biodiversity at all levels, including genetic, becomes increasingly important. Except for tropical forests and true deserts, African wildcats occur across the African continent; however, almost no work has been carried out to assess its genetic status and extent of hybridization with domestic cats. For example, in South Africa it has been argued that the long‐term viability of maintaining pure wildcat populations lies in large protected areas only, isolated from human populations. Two of the largest protected areas in Africa, the Kgalagadi Transfrontier and Kruger National Parks, as well as the size of South Africa and range of landscape uses, provide a model situation to assess how habitat fragmentation and heterogeneity influences the genetic purity of African wildcats. Using population genetic and home range data, we examined the genetic purity of African wildcats and their suspected hybrids across South Africa, including areas within and outside of protected areas. Overall, we found African wildcat populations to be genetically relatively pure, but instances of hybridization and a significant relationship between the genetic distinctiveness (purity) of wildcats and human population pressure were evident. The genetically purest African wildcats were found in the Kgalagadi Transfrontier Park, while samples from around Kruger National Park showed cause for concern, especially combined with the substantial human population density along the park's boundary. While African wildcat populations in South Africa generally appear to be genetically pure, with low levels of hybridization, our genetic data do suggest that protected areas may play an important role in maintaining genetic purity by reducing the likelihood of contact with domestic cats. We suggest that approaches such as corridors between protected areas are unlikely to remain effective for wildcat conservation, as the proximity to human settlements around these areas is projected to increase the wild/domestic animal interface. Thus, large, isolated protected areas will become increasingly important for wildcat conservation and efforts need to be made to prevent introduction of domestic cats into these areas.     

Genetic structure of wildcat (Felis silvestris) populations in Italy

Severe climatic changes during the Pleistocene shaped the distributions of temperate‐adapted species. These species survived glaciations in classical southern refuges with more temperate climates, as well as in western and eastern peripheral Alpine temperate areas. We hypothesized that the European wildcat (Felis silvestris silvestris) populations currently distributed in Italy differentiated in, and expanded from two distinct glacial refuges, located in the southern Apennines and at the periphery of the eastern Alps. This hypothesis was tested by genotyping 235 presumed European wildcats using a panel of 35 domestic cat‐derived microsatellites. To provide support and controls for the analyses, 17 know wildcat x domestic cat hybrids and 17 Sardinian wildcats (F. s. libyca) were included. Results of Bayesian clustering and landscape genetic analyses showed that European wildcats in Italy are genetically subdivided into three well‐defined clusters corresponding to populations sampled in: (1) the eastern Alps, (2) the peninsular Apennines, and (3) the island of Sicily. Furthermore, the peninsular cluster is split into two subpopulations distributed on the eastern (Apennine mountains and hills) and western (Maremma hills and lowlands) sides of the Apennine ridge. Simulations indicated Alpine, peninsular, and Sicilian wildcats were isolated during the Last Glacial Maximum. Population subdivision in the peninsula cluster of central Italy arose as consequence of a more recent expansions of historically or ecologically distinct European wildcat subpopulations associated with distinct the Continental or Mediterranean habitats. This study identifies previously unknown European wildcat conservation units and supports a deep phylogeographical history for Italian wildcats.     

Hybridization between Felis silvestris silvestris and Felis silvestris catus in two contrasted environments in France

European wildcat (Felis silvestris silvestris) populations are fragmented throughout most of the whole range of the subspecies and may be threatened by hybridization with the domestic cat F.s. catus. The underlying ecological processes promoting hybridization remain largely unknown. In France, wildcats are mainly present in the northeast and signs of their presence in the Pyrenees have been recently provided. However, no studies have been carried out in the French Pyrenees to assess their exposure to hybridization. We compared two local populations of wildcats, one living in a continuous forest habitat in the French Pyrenees, the other living in a highly fragmented forest‐agricultural landscape in northeastern France to get insights into the variability of hybridization rates. Strong evidence of hybridization was detected in northeastern France and not in the Pyrenees. Close kin in the Pyrenees were not found in the same geographic location contrary to what was previously reported for females in the northeastern wildcat population. The two wildcat populations were significantly differentiated (F_ST = 0.072) to an extent close to what has been reported (F_ST = 0.103) between the Iberian population, from which the Pyrenean population may originate, and the German population, which is connected to the northeastern population. The genetic diversity of the Pyrenean wildcats was lower than that of northeastern wildcat populations in France and in other parts of Europe. The lower hybridization in the Pyrenees may result from the continuity of natural forest habitats. Further investigations should focus on linking landscape features to hybridization rates working on local populations.     

Spatial organisation of European wildcats (Felis silvestris silvestris) in an agriculturally dominated landscape in Central Europe

For the first time, a telemetry study of European wildcats was conducted outside heavily forested habitats, in an agriculturally-dominated landscape, which is assumed to be a suboptimal habitat in Central Europe. According to the current knowledge of morphological and genetic diagnoses all captured wildcats were purebred, without any hint of recent interbreeding. Our results confirmed the regular use of open landscape habitats also by resident individuals. Sex and age ratios of wildcats, using the open landscapes, were balanced, and one successful reproduction event was recorded. Female annual home-ranges were smaller compared to those recorded in forested habitats. Male annual home-ranges were similar in size, whereas the core areas were smaller than those recorded in adjacent forested habitats. Males had the largest home-ranges during spring and the smallest in summer, whereas females had the largest home-ranges during summer and the smallest during winter/spring. The structure of the apparently purebred population with resident individuals and a reproduction event in an open cultivated landscape may be related to the close proximity (3.5–5 km) of a wildcat core distribution area. As a consequence of our results, the potential range of the European wildcat is increased, because it may occur in agricultural landscapes where sufficient shelter is available. This should be considered in environmental impact analyses and species monitoring.     

Spatial colonization by feral domestic catsFelis catus of former wildcatFelis silvestris silvestris home ranges

Presently, wildcatFelis silvestris silvestris Schreber, 1777 populations are fragmented and rapidly declining in most of Europe. Although habitat destruction possibly constitutes the most serious threat to wildcat survival, hybridisation with feral domestic cats is also a critical problem. However, the mechanisms that allow domestic cats to colonise former wild cat home ranges are yet unclear. The present paper describes the decrease of typical phenotypic wildcats and the increase of phenotypic domestic cats in a remote wild area of Portugal (Serra da Malcata). A field survey using box-traps and radio-tracking between 1998 and 2001 revealed that wildcats were widespread in the study area and no domestic cats were present. A second survey using camera traps between 2005 and 2007 revealed only one wildcat whereas four typical domestic phenotype individuals were photographed. The present study clearly emphasizes the need for urgent measures aimed at preserving wildcat populations. These measures should include a national census of the species and an extensive monitoring of genetic integrity of wildcat populations, followed by the elaboration of a wildcat conservation action plan.     

Morphological discriminants of Scottish wildcats (Felis silvestris), domestic cats (F. catus) and their hybrids

Skull characters of wildcats ( Felis silvestris ), classed as 'old', 'recent' or 'modern', depending on collection date, were compared with those of domestic cats ( F. catus ) and hybrids, using Fisher Linear Discriminant Functions, Principal Component Analyses and Canonical Variates. A key is derived for classification of individual (unknown) skulls. All analyses indicate that 'recent' and 'modern' wildcats were different from those collected earlier, and implied marked changes in the rate of hydridization during this century. We suggest that the older wildcat populations were a relatively 'pure' form but more recent populations contain a significant hybrid component. Although there may be a trend towards re-establishment of the earlier type, an alternative conclusion is that the 'pure' form of wildcat is effectively extinct in Scotland.     

Molecular analysis of hybridisation between wild and domestic cats (Felis silvestris) in Portugal: implications for conservation

The endangered European wildcat (Felis silvestris silvestris) is represented, today, by fragmented and declining populations whose genetic integrity is considered to be seriously threatened by crossbreeding with widespread free-ranging domestic cats. Extensive and recent hybridisation has been described in Hungary and Scotland, in contrast with rare introgression of domestic alleles in Italy and Germany. In Portugal, the wildcat is now listed as VULNERABLE in the Red Book of Portuguese Vertebrates. Nevertheless, genetic diversity of populations and the eventual interbreeding with domestic cats remain poorly studied. We surveyed genetic variation at 12 autosomal microsatellites for 34 wild and 64 domestic cats collected across Portugal. Wild and domestic cats were significantly differentiated both at allele frequencies and sizes (F _ST=0.11, R _ST = 0.18, P < 0.001). Population structure and admixture analyses performed using Bayesian approaches also showed evidence of two discrete groups clustering wild and domestic populations. Results did not show significant genetic divergence among Northern, Central and Southern wildcats. Six morphologically identified wildcats were significantly assigned to the domestic cluster, revealing some discrepancy between phenotypic and genetic identifications. We detected four hybrids (approximately 14%) using a consensus analysis of different Bayesian model-based software. These hybrids were identified throughout all sampled areas, suggesting that hybridisation is of major concern for the appropriate implementation of wildcat conservation strategies in Portugal.     

Large-scale genetic census of an elusive carnivore,the European wildcat (<Emphasis Type="Italic">Felis s. silvestris</Emphasis>)

The European wildcat, Felis silvestris silvestris, serves as a prominent target species for the reconnection of central European forest habitats. Monitoring of this species, however, appears difficult due to its elusive behaviour and the ease of confusion with domestic cats. Recently, evidence for multiple wildcat occurrences outside its known distribution has accumulated in several areas across Central Europe, questioning the validity of available distribution data for this species. Our aim was to assess the fine-scale distribution and genetic status of the wildcat in its central European distribution range. We compiled and analysed genetic samples from roadkills and hundreds of recent hair-trapping surveys and applied phylogenetic and genetic clustering methods to discriminate wild and domestic cats and identify population subdivision. 2220 individuals were confirmed as either wildcat (n = 1792) or domestic cat (n = 342), and the remaining 86 (3.9 %) were identified as hybrids between the two. Remarkably, genetic distinction of domestic cats, wildcats and their hybrids was only possible when taking into account the presence of two highly distinct genetic lineages of wildcats, with a suture zone in central Germany. 44 % of the individual wildcats where sampled outside the previously published distribution. Our analyses confirm a relatively continuous spatial presence of wildcats across large parts of the study area in contrast to previous analyses indicating a highly fragmented distribution. Our results suggest that wildcat conservation and management should take advantage of the higher than previously assumed dispersal potential of wildcats, which may use wildlife corridors very efficiently.     

Genetic distinction of wildcat (Felis silvestris) populations in Europe,and hybridization with domestic cats in Hungary

The genetic integrity and evolutionary persistence of declining wildcat populations are threatened by crossbreeding with widespread free-living domestic cats. Here we use allelic variation at 12 microsatellite loci to describe genetic variation in 336 cats sampled from nine European countries. Cats were identified as European wildcats (Felis silvestris silvestris), Sardinian wildcats (F. s. libyca) and domestic cats (F. s. catus), according to phenotypic traits, geographical locations and independently of any genetic information. Genetic variability was significantly partitioned among taxonomic groups (FST = 0.11; RST = 0.41; P < 0.001) and sampling locations (FST = 0.07; RST = 0.06; P < 0.001), suggesting that wild and domestic cats are subdivided into distinct gene pools in Europe. Multivariate and Bayesian clustering of individual genotypes also showed evidence of distinct cat groups, congruent with current taxonomy, and suggesting geographical population structuring. Admixture analyses identified cryptic hybrids among wildcats in Portugal, Italy and Bulgaria, and evidenced instances of extensive hybridization between wild and domestic cats sampled in Hungary. Cats in Hungary include a composite assemblage of variable phenotypes and genotypes, which, as previously documented in Scotland, might originate from long lasting hybridization and introgression. A number of historical, demographic and ecological conditions can lead to extensive crossbreeding between wild and domestic cats, thus threatening the genetic integrity of wildcat populations in Europe.     

Low rates of hybridization between European wildcats and domestic cats in a human‐dominated landscape

Hybridization between wild species and their domestic congeners is considered a major threat for wildlife conservation. Genetic integrity of the European wildcat, for instance, is a concern as they are outnumbered by domestic cats by several orders of magnitude throughout its range. We genotyped 1,071 individual wildcat samples obtained from hair traps and roadkills collected across the highly fragmented forests of western Central Europe, in Germany and Luxembourg, to assess domestic cat introgression in wildcats in human‐dominated landscapes. Analyses using a panel of 75 autosomal SNPs suggested a low hybridization rate, with 3.5% of wildcat individuals being categorized as F1, F2, or backcrosses to either parental taxon. We report that results based on a set of SNPs were more consistent than on a set of 14 microsatellite markers, showed higher accuracy to detect hybrids and their class in simulation analyses, and were less affected by underlying population structure. Our results strongly suggest that very high hybridization rates previously reported for Central Europe may be partly due to inadequate choice of markers and/or sampling design. Our study documents that an adequately selected SNP panel for hybrid detection may be used as an alternative to commonly applied microsatellite markers, including studies relying on noninvasively collected samples. In addition, our finding of overall low hybridization rates in Central European wildcats provides an example of successful wildlife coexistence in human‐dominated, fragmented landscapes.     

Modelling the dynamic biogeography of the wildcat: implications for taxonomy and conservation

There is still no clear consensus on how to relate geographical variation in the morphology and genetics of the globally widespread wildcat Felis silvestris to its taxonomy and systematics. Reconstructing the dynamic biogeography of the wildcat provides insight into how current geographical patterns of morphological and molecular variation may have developed. A geographical information system was used to infer climate-change influences using a deduced distribution model (DDM) to reconstruct the wildcat's geographical distribution at four points in time from the Last Glacial Maximum [LGM; 18 000 years before present ( bp )] until today. The DDM for 9000  bp , when mean global temperatures were 2 °C more than today, provides insight into how current global warming will affect the wildcat's distribution 50–100 years into future. Modelled distributions were assessed against known geographical barriers or unsuitable habitats, which may have separated populations and led to known morphological and genetic divergence. The DDM_today corresponds well with known contemporary wildcat distribution records, except where wildcats would be expected to be excluded (e.g. high human population densities, potential competitors, inaccessible islands). The DDM_today also corresponds closely with the results of recent studies on skull morphometrics and phylogeography, which support hypothesized colonizations of Africa and Asia from Europe during the late Pleistocene. Although DDM palaeo-distributions are more uncertain, they correspond to expected dramatic declines in northern Eurasia during the LGM, and significant distributional decline in central Asia, the Sahara and southern Africa, owing to increased aridity during climate cooling. From the DDM₉₀₀₀ model moderate global warming is hypothesized to impact minimally on wildcats, except in the Middle East and south-west Asia.     

European wildcat populations are subdivided into five main biogeographic groups: consequences of Pleistocene climate changes or recent anthropogenic fragmentation?

Extant populations of the European wildcat are fragmented across the continent, the likely consequence of recent extirpations due to habitat loss and over‐hunting. However, their underlying phylogeographic history has never been reconstructed. For testing the hypothesis that the European wildcat survived the Ice Age fragmented in Mediterranean refuges, we assayed the genetic variation at 31 microsatellites in 668 presumptive European wildcats sampled in 15 European countries. Moreover, to evaluate the extent of subspecies/population divergence and identify eventual wild × domestic cat hybrids, we genotyped 26 African wildcats from Sardinia and North Africa and 294 random‐bred domestic cats. Results of multivariate analyses and Bayesian clustering confirmed that the European wild and the domestic cats (plus the African wildcats) belong to two well‐differentiated clusters (average Ф_ST = 0.159, R_st  = 0.392, P > 0.001; Analysis of molecular variance [AMOVA]). We identified from c. 5% to 10% cryptic hybrids in southern and central European populations. In contrast, wild‐living cats in Hungary and Scotland showed deep signatures of genetic admixture and introgression with domestic cats. The European wildcats are subdivided into five main genetic clusters (average Ф_ST = 0.103, R_st  = 0.143, P > 0.001; AMOVA) corresponding to five biogeographic groups, respectively, distributed in the Iberian Peninsula, central Europe, central Germany, Italian Peninsula and the island of Sicily, and in north‐eastern Italy and northern Balkan regions (Dinaric Alps). Approximate Bayesian Computation simulations supported late Pleistocene–early Holocene population splittings (from c. 60 k to 10 k years ago), contemporary to the last Ice Age climatic changes. These results provide evidences for wildcat Mediterranean refuges in southwestern Europe, but the evolution history of eastern wildcat populations remains to be clarified. Historical genetic subdivisions suggest conservation strategies aimed at enhancing gene flow through the restoration of ecological corridors within each biogeographic units. Concomitantly, the risk of hybridization with free‐ranging domestic cats along corridor edges should be carefully monitored.     

Experience obtained from box trapping and handling wildcats in Slovenia

WildcatsFelis silvestris Schreber, 1775 were captured for radio collaring as a part of a study of their spatial distribution and social organisation in southern Slovenia between 1999 and 2001. Double-door box traps, with a roof that bears easily break (bear permeable traps), have been used to capture individuals. The distances between traps were between 550 to 2200 m. They were set out on logging roads and narrow trails in the forest. Nine wildcats, one lynx Lynx lynx (Linnaeus, 1758) and one feral cat were caught as target species and 19 badgersMeles meles and one bear cubUrsus arctos as non-targets. The catching success was 1 wildcat/58 trap-days and seems to be in correlation with the lunar cycle. Overall, 7 males and 2 female wildcats were captured which might indicate sex biased trapping selection. Methodological improvements shortened the time of handling procedures. Improved field protocols as well as restraining and immobilisation procedures increased reliability and safety of drug administrations, decreased potential chances for injuries and reduced overall stress of captured animals.     

Genetic diversity and integrity of German wildcat (Felis silvestris) populations as revealed by microsatellites,allozymes, and mitochondrial DNA sequences

As a consequence of persecution and habitat fragmentation, wildcats (Felis silvestris silvestris) in Western Europe have experienced a severe reduction in population numbers and sizes. The remaining wildcat populations are considered to be endangered by losses of genetic variability and by hybridisation with free-ranging domestic cats. To investigate genetic diversity within and among wild and domestic cat populations in Germany and to estimate the extent of gene flow between both forms, we analysed a total of 266 individuals. PCR-amplification and sequencing of 322 base pairs of a highly variable part of the mitochondrial control region (HV1) of 244 specimens resulted in 41 haplotypes with 31 polymorphic sites. Additionally, eight microsatellite loci were examined for those 244 cats. Moreover, a total of 46 wildcats and 22 domestic cats could be genotyped for 13 polymorphic out of 31 enzyme loci. Genetic variability in both groups was generally high. Variability in domestic cat populations was higher than in wildcat populations. Almost no differentiation between domestic cat populations could be found (F_ST for microsatellites=3%). In contrast, wildcat populations differed significantly from one another (F_ST for microsatellites=9.55%) Within the smaller wildcat populations, a reduction of genetic diversity was detectable with regard to the nuclear DNA. Wildcat and domestic cat mitochondrial haplotypes were separated, suggesting a very low level of maternal gene flow between both forms. In microsatellites and to a somewhat lesser extent in allozymes, wildcats and domestic cats showed distinct differentiation, suggesting an only low extent of past hybridisation in certain populations. The microsatellite data set indicated a significantly reduced effective population size (bottleneck) in the recent past for one German wildcat population.     

The Genetic Integrity of the Ex Situ Population of the European Wildcat (Felis silvestris silvestris) Is Seriously Threatened by Introgression from Domestic Cats (Felis silvestris catus)

Studies on the genetic diversity and relatedness of zoo populations are crucial for implementing successful breeding programmes. The European wildcat, Felis s. silvestris, is subject to intensive conservation measures, including captive breeding and reintroduction. We here present the first systematic genetic analysis of the captive population of Felis s. silvestris in comparison with a natural wild population. We used microsatellites and mtDNA sequencing to assess genetic diversity, structure and integrity of the ex situ population. Our results show that the ex situ population of the European wildcat is highly structured and that it has a higher genetic diversity than the studied wild population. Some genetic clusters matched the breeding lines of certain zoos or groups of zoos that often exchanged individuals. Two mitochondrial haplotype groups were detected in the in situ populations, one of which was closely related to the most common haplotype found in domestic cats, suggesting past introgression in the wild. Although native haplotypes were also found in the captive population, the majority (68%) of captive individuals shared a common mtDNA haplotype with the domestic cat (Felis s. catus). Only six captive individuals (7.7%) were assigned as wildcats in the STRUCTURE analysis (at K = 2), two of which had domestic cat mtDNA haplotypes and only two captive individuals were assigned as purebred wildcats by NewHybrids. These results suggest that the high genetic diversity of the captive population has been caused by admixture with domestic cats. Therefore, the captive population cannot be recommended for further breeding and reintroduction.     

Toward a genome-wide approach for detecting hybrids: informative SNPs to detect introgression between domestic cats and European wildcats (Felis silvestris)

Endemic gene pools have been severely endangered by human-mediated hybridization, which is posing new challenges in the conservation of several vertebrate species. The endangered European wildcat is an example of this problem, as several natural populations are suffering introgression of genes from the domestic cat. The implementation of molecular methods for detecting hybridization is crucial for supporting appropriate conservation programs on the wildcat. In this study, genetic variation at 158 single-nucleotide polymorphisms (SNPs) was analyzed in 139 domestic cats, 130 putative European wildcats and 5 captive-bred hybrids (N=274). These SNPs were variable both in wild (H_E=0.107) and domestic cats (H_E=0.340). Although we did not find any SNP that was private in any population, 22 SNPs were monomorphic in wildcats and pairwise F_CT values revealed marked differences between domestic and wildcats, with the most divergent 35 loci providing an average F_CT>0.74. The power of all the loci to accurately identify admixture events and discriminate the different hybrid categories was evaluated. Results from simulated and real genotypes show that the 158 SNPs provide successful estimates of admixture, with 100% hybrid individuals (two to three generations in the past) being correctly identified in STRUCTURE and over 92% using the NEWHYBRIDS'' algorithm. None of the unclassified cats were wrongly allocated to another hybrid class. Thirty-five SNPs, showing the highest F_CT values, provided the most parsimonious panel for robust inferences of parental and first generations of admixed ancestries. This approach may be used to further reconstruct the evolution of wildcat populations and, hopefully, to develop sound conservation guidelines for its legal protection in Europe.     

The importance of small-scale structures in an agriculturally dominated landscape for the European wildcat (Felis silvestris silvestris) in central Europe and implications for its conservation

The European wildcat (Felis silvestris silvestris) is a threatened and elusive species that was previously considered to be forest-bound in central Europe. For the first time, we caught and radio-collared wildcats outside heavily forested habitats to investigate their habitat utilization pattern. We used a generalized linear modelling framework to test our hypotheses that sex and season influence habitat selection in addition to habitat variables. Our results reveal a gender difference in habitat selection: Females were more restricted to areal shelter habitats and avoided the areas near roads more than did males. Males used more linear shelter habitats such as watercourses or hedges and avoided the proximity to settlements more than did females. The probability of wildcat occurrence far from shelter habitats was higher in summer than in winter, probably due to high coverage and shelter provided by crops. The same pattern applied to the proximity to roads. We concluded that shelter habitats are one of the key factors for the occurrence of wildcats in agriculturally dominated landscapes. We recommend a management strategy that enhances structural heterogeneity in the agricultural landscape by conserving small-scale structures such as copses, hedges and wide field margins. Other species, such as the gray-partridge (Perdix perdix) and the common quail (Coturnix corturnix), can also benefit from these habitat recommendations. Additionally, this management strategy simultaneously creates habitat connectivity.     

Development of SNP markers identifying European wildcats,domestic cats,and their admixed progeny

Introgression can be an important evolutionary force but it can also lead to species extinction and as such is a crucial issue for species conservation. However, introgression is difficult to detect, morphologically as well as genetically. Hybridization with domestic cats (Felis silvestris catus) is a major concern for the conservation of European wildcats (Felis s. silvestris). The available morphologic and genetic markers for the two Felis subspecies are not sufficient to reliably detect hybrids beyond first generation. Here we present a single nucleotide polymorphism (SNP) based approach that allows the identification of introgressed individuals. Using high‐throughput sequencing of reduced representation libraries we developed a diagnostic marker set containing 48 SNPs (Fst  > 0.8) which allows the identification of wildcats, domestic cats, their hybrids and backcrosses. This allows assessing introgression rate in natural wildcat populations and is key for a better understanding of hybridization processes.     

Genetic identification of wild and domestic cats (Felis silvestris) and their hybrids using Bayesian clustering methods

Crossbreeding with free-ranging domestic cats is supposed to threaten the genetic integrity of wildcat populations in Europe, although the diagnostic markers to identify "pure" or "admixed" wildcats have never been clearly defined. Here we use mitochondrial (mt) DNA sequences and allelic variation at 12 microsatellite loci to genotype 128 wild and domestic cats sampled in Italy which were preclassified into three separate groups: European wildcats (Felis silvestris silvestris), Sardinian wildcats (Felis silvestris libyca), and domestic cats (Felis silvestris catus), according to their coat color patterns, collection localities, and other phenotypical traits, independently of any genetic information. For comparison, we included some captive-reared hybrids of European wild and domestic cats. Genetic variability was significantly partitioned among the three groups (mtDNA estimate of F(ST) = 0.36; microsatellite estimate of R(ST) = 0.30; P < 0.001), suggesting that morphological diversity reflects the existence of distinct gene pools. Multivariate ordination of individual genotypes and clustering of interindividual genetic distances also showed evidence of distinct cat groups, partially congruent with the morphological classification. Cluster analysis, however, did not enable hybrid cats to be identified from genetic information alone, nor were all individuals assigned to their populations. In contrast, a Bayesian admixture analysis simultaneously assigned the European wildcats, the Sardinian wildcats, and the domestic cats to different clusters, independent of any prior information, and pointed out the admixed gene composition of the hybrids, which were assigned to more than one cluster. Only one putative Sardinian wildcat was assigned to the domestic cat cluster, and one presumed European wildcat showed mixed (hybrid) ancestry in the domestic cat gene pool. Mitochondrial DNA sequences indicated that three additional presumed European wildcats might have hybrid ancestry. These four cats were sampled from the same area in the northernmost edge of the European wildcat distribution in the Italian Apennines. Admixture analyses suggest that wild and domestic cats in Italy are distinct, reproductively isolated gene pools and that introgression of domestic alleles into the wild-living population is very limited and geographically localized.     

Potential barriers to gene flow in the endangered European wildcat (Felis silvestris)

The European wildcat (Felis silvestris silvestris) is a focal species for conservation in many European countries. After a severe population decline during the 19th century, many populations became extinct or isolated. Within Germany, suitable wildcat habitat is assumed to be highly fragmented. We thus investigated fine-scale genetic structure of wildcat populations in Central Germany across two major potential barriers, the Rhine River with its valley and a major highway. We analyzed 260 hair and tissue samples collected between 2006 and 2011 in the Taunus and Hunsrück mountain ranges (3,500 km² study area). We identified 188 individuals by genotyping 14 microsatellite loci, and found significant genetic substructure in the study area. Both the Rhine River and the highway were identified as significant barrier to gene flow. While the long-term effect of the river has led to stronger genetic differentiation in the river compared to the highway, estimates of current gene flow and relatedness across barriers indicated a similar or even stronger barrier effect to ongoing wildcat dispersal of the highway. Despite these barrier effects, we found evidence for the presence of recent migration across both the river and the highway. Our study thus suggests that although wildcats have the capability of dispersal across major anthropogenic and natural landscape barriers, these structures still lead to an effective isolation of populations as reflected by genetic analysis. The results strengthen the need for currently ongoing national strategies of wildcat conservation aiming for large scale habitat connectivity.