Evaluation of anatomical characters and the question of hybridization with domestic cats in the wildcat population of Thuringia, Germany

Abstract

GermanyÕs large population of wildcats (Felis silvestris silvestris) can be clearly distinguished from domestic cats on the basis of morphological characters. However, an examination of 71 specimens from Thuringia also illustrates the risks involved in using only a few such characters. The most reliable tool for identification in the field are three pelage characters (distinctness of tail bands, stripes on the nape and stripes on the shoulder). Only two morphological characters (intestine length and cranial volume) are unambiguous and demonstrate no overlap in distribution between domestic cats and wildcats. A linear discriminant analysis with forward selection of variables showed that only five skull variables are necessary to distinguish all four groups (subspecies · sex). Additionally, the high degree of correlation between most of the 49 variables examined (as indicated by PearsonÕs r correlation matrix) speaks against the utility of measuring such high numbers of characters in the future. Principal component analysis (PCA) enabled the subspecies to be separated clearly. The first PCA axis was highly correlated with variables characterizing overall body size, thus separating male and female into wildcats and domestic cats. Even when the chief differentiating characters are missing, the PCA still resulted in a good separation of subspecies. None of the genetically determined hybrids could have been deciphered unambiguously using the morphological characters still intact after a road death. Hybridization seems to occur whenever wildcats change their ecological function and become field cats. The impulse to hybridize seems to come much more from the wildcat side than the side of feral cats, and deforestation represents the major threat to the wildcat.

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

“…Eighteen putative wildcats were allocated with high posterior probabilities to the domestic cluster and therefore were excluded from the analysis. This was in agreement with previous reports for the species (for example, Oliveira et al, 2008a, b), suggesting that morphological identification of European wildcat and domestic cats might not be as straightforward as some authors advocate (Ragni and Possenti, 1996;Daniels et al, 1998;Kitchener et al, 2005;Puzachenko, 2002;Yamaguchi et al, 2004a, b;Krüger et al, 2009;Platz et al, 2011). A variety of issues could lead to misclassification, including (i) dead animals might have been highly degraded at the time of collection and discrimination of obvious morphological characters might not be possible; (ii) cats belong to past generations of admixture and demarked diagnostic traits are no longer expressed; (iii) samples were noninvasively collected (for example, scats and hairs) and morphological discrimination was not possible; (iv) overlap of morphological features; and (v) conservation biologist and naturalist bias of their morphological evaluation toward the collection of wild specimens.…”

Large-scale genetic census of an elusive carnivore, the European wildcat (Felis s. silvestris)

“…Interestingly, precise knowledge on wildcat distribution was lacking until recently, due to its elusive nature and the fact that the species is morphologically similar to wildcoloured domestic cats (Krüger et al 2009;Müller 2011). As wildcats need to be monitored regularly by EU law (European Council Directive 92/43/EEC, Appendix IV), funds need to be allocated for this purpose.…”

“…While traditional wildcat monitoring data is based on direct sightings, expert questionnaires, live trapping and roadkill collections (Birlenbach and Klar 2009;Oliveira et al 2008;Say et al 2012;Simon et al 2005), a recent noninvasive monitoring approach using hairs collected with so-called lure stick hair traps has been established allowing for standardized large scale wildcat assessments Steyer et al 2013). The lure stick method enables a DNA-based distinction between wild and domestic cat, which promises to solve the long-standing difficulty of safe discrimination under field conditions and the virtual impossibility to safely identify hybrids even under the presence of fresh roadkill material or live-trapped cats (Daniels et al 1998;Eichholzer 2010;Krüger et al 2009). As hybridisation with the omnipresent domestic cat was identified as a major threat to the scattered wildcat populations in Europe (Beaumont et al 2001;Devillard et al 2014;Nussberger et al 2014;O'Brien et al 2009;Pierpaoli et al 2003), the safe discrimination of wild and domestic cats and their hybrids poses another major advantage of lure stick-based monitoring compared to traditional survey methods.…”

Monitoring European wildcat Felis silvestris populations using scat surveys in central Spain: are population trends related to wild rabbit dynamics or to landscape features?

“…Furthermore, wildcats and domestic cats belong to the same species (e.g., Sunquist and Sunquist 2002;Driscoll et al 2007). In fact, hybrids play the same ecological role in the wild as wildcats, and many are even morphologically indistinguishable from them (e.g., Daniels et al 2001;Biró et al 2005;Hertwig et al 2009;Krüger et al 2009). Therefore, and especially in the latter case, it is not clear why an essential difference must be made between the two cat groups.…”

“…Thus, for the European wildcat, being a legally protected species and of conservation concern imply that further studies on its biology are crucial (Stahl and Artois 1991;Council of Europe 1993;Lozano and Malo 2012) to guarantee improved diagnoses of conservation problems and identify potential tools for preserving wildcats in Europe (Stahl and Artois 1991;McOrist and Kitchener 1994;). Indeed, in recent years, a significant increase in the number of studies on wildcats has taken place, especially in genetics (e.g., Pierpaoli et al 2003; Lecis et al 2006;Oliveira et al 2008;Hertwig et al 2009;Say et al 2012), morphology (e.g., Yamaguchi et al 2004;Kitchener et al 2005;Krüger et al 2009), trophic ecology (e.g., Malo et al 2004;Biró et al 2005;Lozano et al 2006;Piñeiro and Barja 2011), and habitat preferences (e.g., Lozano et al 2003Biró et al 2004;Klar et al 2008;Monterroso et al 2009;Lozano 2010).…”