Pedigree‐based assignment tests for reversing coyote (Canis latrans) introgression into the wild red wolf (Canis rufus) population

Abstract

The principal threat to the persistence of the endangered red wolf (Canis rufus) in the wild is hybridization with the coyote (Canis latrans). To facilitate idengification and removal of hybrids, assignment tests are developed which use genotype data to estimate identity as coyote, 1/4, 1/2, 3/4 or full red wolf. The tests use genotypes from the red wolves that founded the surviving population and the resulting pedigree, rather than a contemporary red wolf sample. The tests are evaluated by analysing both captive red wolves at 18 microsatellite loci, and data simulated under a highly parameterized, biologically reasonable model. The accuracy of assignment rates are generally high, with over 95% of known red wolves idengified correctly. There are, however, tradeoffs between ambiguous assignments and misassignments, and between misidengifying red wolves as hybrids and hybrids as red wolves. These result in a compromise between limiting introgression and avoiding demographic losses. The management priorities and level of introgression determine the combination of test and removal strategy that best balances these tradeoffs. Ultimately, we conclude that the use of the assignment tests has the capacity to arrest and reverse introgression. To our knowledge, the presented approach is novel in that it accounts for genetic drift when the genotypes under analysis are temporally separated from the reference populations to which they are being assigned. These methods may be valuable in cases where reference databases for small populations have aged substantially, pedigree information is available or data are generated from historical samples.

Genetic nature of eastern wolves: Past, present and future

“…If C. lycaon is recognized as another Canis species in the Great Lakes region, current numbers of C. lupus would be overestimated, potentially influencing its conservation status. Further, in the southern USA, attempts have been made to identify and remove both hybrid C. rufus individuals with C. latrans DNA and C. latrans individuals within certain animal reserves to promote a pure genetic stock of C. rufus (see Adams et al 2003;Miller et al 2003). Such a program is likely not practical, nor desirable for eastern wolves that now comprise a continuum of morphotypes in the Great Lakes region, from larger C. lycaon animals with C. lupus genetic material in the northwest to smaller C. lycaon with C. latrans genetic material in the southeast of its current range (Grewal 2001; Figure 3).…”

Genetic monitoring as a promising tool for conservation and management

“…In recognition of this reality, genetic monitoring of hybridization has been proposed for many species, including Canada lynx-bobcat Lynx rufus [24], coyote Canis latrans-red wolf Canis rufus [25], and spotted owl Strix occidentalis-barred Barcoding: the use of short, standardized DNA sequences, typically from a mitochondrial gene, to identify and discover species quickly and easily. Capture-mark-recapture (CMR): field sampling method used to estimate population size or vital rates (i.e.…”

The Contribution of the Captive Breeding in Mexican Grey Wolf (<i>Canis lupus baileyi</i>) and Red Wolf (<i>Canis rufus</i>)

“…Finally, 14 individuals have been chosen as the initial founders of captive breeding (Phillips et al, 2003).However, the issues about the genetic purity and specialness of this population have been argued (Roy et al, 1994). The 14 founders have been examined to obtain the biological information (Miller et al, 2003) and figured out the relationship with other canids species and the ancestors of these founders (Walker et al, 2002).…”

“…However, the coyotes started to inhabit these areas and hybridized with the red wolves (Phillips et al, 2003). Therefore, the hybridization becomes the most serious threat to the pure genetic red wolves in the wild (Allendorf et al, 2001;Miller et al, 2003). A research report implicated that the hybridization and introgression of coyote events have been observed among the reintroduction animals (L. Waits, personal communication).…”