Describing a developing hybrid zone between red wolves and coyotes in eastern North Carolina, USA

Abstract

When hybridizing species come into contact, understanding the processes that regulate their interactions can help predict the future outcome of the system. This is especially relevant in conservation situations where human activities can influence hybridization dynamics. We investigated a developing hybrid zone between red wolves and coyotes in North Carolina, USA to elucidate patterns of hybridization in a system heavily managed for preservation of the red wolf genome. Using noninvasive genetic sampling of scat, we surveyed a 2880 km2 region adjacent to the Red Wolf Experimental Population Area (RWEPA). We combined microsatellite genotypes collected from this survey with those from companion studies conducted both within and outside the RWEPA to describe the gradient of red wolf ancestry. A total of 311 individuals were genotyped at 17 loci and red wolf ancestry decreased along an east–west gradient across the RWEPA. No red wolves were found outside the RWEPA, yet half of individuals found within this area were coyotes. Hybrids composed only 4% of individuals within this landscape despite co‐occurrence of the two species throughout the RWEPA. The low proportion of hybrids suggests that a combination of active management and natural isolating mechanisms may be limiting intermixing within this hybrid system.

Space Use and Habitat Selection by Resident and Transient Red Wolves (Canis rufus)

“…Hinton [69–70] suggested as red wolves and coyotes approached each other in body size, similar use of prey and space may reduce behavioral incompatibilities between consorting individuals and permit the successful formation of congeneric pairs responsible for creating red wolf/coyote hybrids. Because hybridization is a primary threat to the conservation and persistence of eastern wolves [14,18,71–72] and red wolves [3,16,38,21–22,73], we suggest further studies are needed to better understand behaviors and conditions that allow individuals of Canis populations to successfully form congeneric breeding pairs responsible for hybridization.…”

“…Indeed, Hinton et al [3] reported increased occurrence of coyote encroachment and replacement of resident red wolves after resident wolf breeders were killed by humans. Although red wolves exhibit assortative mating patterns [16,38], coyotes were capable of pair-bonding with surviving red wolves when no transient wolves were available to encroach into territories that were disrupted by anthropogenic mortality [3]. Consequently, pair-bonding with coyotes by surviving red wolf residents formed congeneric breeding pairs that hybridized [3,22,33].…”

Genetic and genomic monitoring with minimally invasive sampling methods

“…For some species, hybridization and introgression are major threats to population and species persistence creating a need for long‐term genetic monitoring (Allendorf, Leary, Spruell, & Wenburg, ). Genetic monitoring approaches using MIS have been applied to detect hybridization in multiple carnivore species including grey wolves (Caniglia et al., ; Godinho et al., ; Kopaliani, Shakarashvili, Gurielidze, Qurkhuli, & Tarkhnishvili, ; Monzón, Kays, & Dykhuizen, ), Eastern wolves ( Canis lycaon , Benson, Patterson, & Wheeldon, ), red wolves ( Canis rufus ; Adams et al., ; Bohling et al., ) and wildcats ( Felix silvestris silvestris ; Anile, Ragni, Randi, Mattucci, & Rovero, ; Steyer et al., ). The majority of these studies have used mitochondrial DNA and microsatellite markers, but a few have used SNPs to detect hybridization or monitor grey wolves (Kraus et al., ; Monzón et al., ) and hybridization between wildcats and domestic cats (Nussberger et al., ; Oliveira et al., ).…”

Size‐assortative choice and mate availability influences hybridization between red wolves (Canis rufus) and coyotes (Canis latrans)

“…Factors influencing assortative mating in Canis taxa are likely multifaceted with a diversity of behavioral and ecological correlates that may influence hybridization (Benson & Patterson, ; Bohling et al., ; Hinton et al., ; Hinton, Ashley et al., ; Rutledge, Garroway et al., ; Rutledge, White et al., ). Essentially, hybridization results when individual red wolves and coyotes consort to form congeneric breeding pairs that defend territories and produce hybrid litters (Hinton et al., ; Hinton, Brzeski et al., ; Hinton, Ashley et al., ).…”