Identification of Wolf-Dog Hybrids in Europe – An Overview of Genetic Studies

Abstract

Significant development of genetic tools during the last decades provided opportunities for more detailed analyses and deeper understanding of species hybridization. New genetic markers allowed for reliable identification of admixed individuals deriving from recent hybridization events (a few generations) and those originating from crossings up to 19 generations back. Implementation of microsatellites (STRs) together with Bayesian clustering provided abundant knowledge regarding presence of admixed individuals in numerous populations and helped understand the problematic nature of studying hybridization (i.a., defining a reliable thresholds for recognizing individuals as admixed or obtaining well-grounded results representing actual proportion of hybrids in a population). Nevertheless, their utilization is limited to recent crossbreeding events. Single Nucleotide Polymorphisms (SNPs) proved to be more sensible tools for admixture analyses furnishing more reliable knowledge, especially for older generation backcrosses. Small sets of Ancestry Informative Markers (AIMs) of both types of markers were effective enough to implement in monitoring programs, however, SNPs seem to be more appropriate because of their ability to identify admixed individuals up to 3rd generations. The main aim of this review is to summarize abundant knowledge regarding identification of wolf-dog hybrids in Europe and discuss the most relevant problems relating to the issue, together with advantages and disadvantages of implemented markers and approaches.

Genome‐wide variant analyses reveal new patterns of admixture and population structure in Australian dingoes

“…Interestingly, dingoes from the Big Desert, South, East or Captive population clusters were more often miscategorised by microsatellite-based methods than those from the West (Table 5). Our findings are consistent with reports from a wide range of other species demonstrating that genome-wide SNP analysis outperforms microsatellites in terms of accurate identification of ancestry and admixture (Dziech, 2021;Mattucci et al, 2019;McFarlane et al, 2020;Steyer et al, 2018;Stroupe et al, 2022;Szatmári et al, 2021;Vaha & Primmer, 2006;Väli et al, 2010;Zimmerman et al, 2020).…”

“…We considered that the occurrence of different backcross classes in wild dingo populations may inform conservation and management policy directions, with some previous studies considering animals with >93% dingo ancestry as pure (Allen et al, 2017). Therefore, we categorised backcrosses as being either: (1) historical backcrosses (>93% parental ancestry) that were likely to be third generation or higher or (2) recent backcrosses (55%–93% parental ancestry) which described animals that were likely to have had a dingo × dog hybrid ancestor in the last one to three generations (Dziech, 2021; Harmoinen et al, 2021; McFarlane & Pemberton, 2019). A map depicting the FastStructure ancestry assignment of each wild origin sample was created using the QGIS v3.12 (QGIS, 2020).…”

“…(1) historical backcrosses (>93% parental ancestry) that were likely to be third generation or higher or (2) recent backcrosses (55%-93% parental ancestry) which described animals that were likely to have had a dingo × dog hybrid ancestor in the last one to three generations (Dziech, 2021;Harmoinen et al, 2021;McFarlane & Pemberton, 2019).…”

“Guess Who’s Coming to Dinner”: Molecular Tools to Reconstruct multilocus Genetic Profiles from Wild Canid Consumption Remains

“…Our methodological procedures could be further improved by using highly performing markers to genotype non-invasively collected samples such as metabarcoding or highly informative and easily inter-lab comparable SNP panels, in cases of canid or felid predation on wildlife or other domestic pets to establish the real taxonomic status of the predators through a finer scale admixture identification and to provide a more reliable assessment of their potential impact on other threatened species [ 20 , 47 , 48 , 49 ].…”

A Validated Molecular Protocol to Differentiate Pure Wolves, Dogs and Wolf x Dog Hybrids through a Panel of Multiplexed Canine STR Markers

“…Different methods are currently available for DNA typing in wild canids [7,8], but validation studies are lacking for most of them. On the other hand, STR-based commercial kits were developed and validated for some domestic animals, like dogs and cattle, while they are not available for non-model and wild species [9].…”