Continental-scale assessment of the hybrid zone between bobcat and Canada lynx

Interspecific hybridization and introgression are of conservation concern because they can lead to lower fitness, and in some cases, extinction of the parental population or species. Alternatively, hybridization can lead to increased fitness (i.e., heterosis) via generation of new genetic combinations and increased adaptive potential. There have been isolated observations of the Canada lynx (Lynx canadensis) hybridizing with the closely-related bobcat (Lynx rufus), but no comprehensive study has been undertaken of lynx-bobcat hybridization across their geographic ranges. The lynx distribution in North America has contracted by 40% from its historical range, and hybridization with bobcats is a potential, uncertain threat to lynx conservation. We conducted a continental-scale assessment of the prevalence of hybridization and genetic introgression between lynx (n = 1776, Canada and Alaska, USA) and bobcat (n = 1075, Canada and conterminous USA). Using control region sequences and clustering of microsatellite data, we found that the prevalence of genetic introgression was relatively low (7 of 2851 individuals (0.24%)). We found evidence of backcrossing to both lynx and bobcat parental types, suggesting that hybrids can be fertile. If the abundance of Canada lynx at the southern extent of its distribution is low relative to bobcat, hybridization and backcrossing with bobcat over several generations could result in the loss of lynx in areas of sympatry. If climate warming results in the bobcat distribution shifting northward towards the southern extent of the lynx distribution, the likelihood of interspecific hybridization could increase.