INCREASING DISTRIBUTION OF NONNATIVE RED FOX (VULPES VULPES) HAPLOTYPES WITHIN THE RANGE OF THE NATIVE SACRAMENTO VALLEY RED FOX (V. V. PATWIN)

Sophie Preckler-Quisquater; UC Davis - Mammalian Ecology and Conservation Unit; squisquater@ucdavis.edu; Tom, J, Batter, Stacy, Anderson, Ben, N, Sacks

The Sacramento Valley red fox (Vulpes vulpes patwin) is a unique subspecies endemic to the Sacramento Valley (SV) and is genetically distinct from the non-native red fox currently occupying contiguous parts of California's lowlands. Although non-native red foxes have occurred adjacent to the native range since the 1960s, hybridization between native and non-native red foxes was previously (2007-2009) discovered only within a restricted contact zone, while the core region of the SV range remained 100% native. This stability was interpreted to represent resistance to genetic introgression. More recently (2012-2015), we sampled a moderate number of sites within this core range to discover that ~35% contained non-native mitochondrial haplotypes. Although preliminary, this apparent rapid increase (0 to ~35%) in nonnative haplotype prevalence over the past several years represents a potentially serious threat and raises questions as to the mechanism behind this sudden shift. We hypothesize that the fitness of native foxes has declined more so than that of nonnative and hybrid foxes in response to the extreme drought of the past several years.