Recently, techniques available for identifying clusters of individuals or boundaries between clusters using genetic data from natural populations have expanded rapidly. Consequently, there is a need to evaluate these different techniques. We used spatially-explicit simulation models to compare three spatial Bayesian clustering programs and two edge detection methods. Spatially-structured populations were simulated where a continuous population was subdivided by barriers. We evaluated the ability of each method to correctly identify boundary locations while varying: (i) time after divergence, (ii) strength of isolation by distance, (iii) level of genetic diversity, and (iv) amount of gene flow across barriers. To further evaluate the methods’ effectiveness to detect genetic clusters in natural populations, we used previously published data on North American pumas and a European shrub. Our results show that with simulated and empirical data, the Bayesian spatial clustering algorithms outperformed direct edge detection methods. All methods incorrectly detected boundaries in the presence of strong patterns of isolation by distance. Based on this finding, we support the application of Bayesian spatial clustering algorithms for boundary detection in empirical datasets, with necessary tests for the influence of isolation by distance.

Hybridisation and gene introgression are important sources of diversification, the relevance of which in the evolutionary processes is well recognised. Their fitness consequences in animal populations, however, are not sufficiently well understood, despite hybridisation rates becoming increasingly important worldwide following human‐related activities such as domestication, game management and habitat alteration. In Europe, the density and distribution of native ungulates have largely been influenced by humans since pre‐historic times. This, alongside the introduction of non‐native and domesticated species, may bear major consequences at the genetic and population levels. We provide an updated overview of recent hybridisation events in wild European ungulates; we describe their ecological drivers, extent, current distribution, potential consequences and proposed management strategies. We reviewed the scientific literature published between 2000 and 2018 and found that confirmed hybridisation was described in 75 of the 89 references we included, involving nearly all the species that we investigated. Most researchers relied on genetic information for hybrid identification, which often involved a domestic counterpart. However, introductions and translocations also led to crossbreeding between wild ungulate (sub)species. Only 43 papers provided management recommendations, mostly focused on preventing hybridisation and removing hybrids. Hybridisation proved to be relatively common in several ungulate taxa in Europe. Despite reported changes in phenotype and fitness‐related traits in some species, the consequences of hybridisation for adaptation, life history, and evolutionary potential remain largely unknown. The current conservation paradigm aims to prevent the spread of domestic or non‐native genes in native populations; accordingly, conservation plans should: 1) determine the genetic origin of possible source populations; 2) protect native populations from the risk of crossbreeding with non‐native ones, and 3) establish permanent monitoring.

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