Aim Climate changes in the past had a deep impact on the evolutionary history of many species and left genetic signatures that are often still detectable today. We investigated the geographical pattern of mitochondrial DNA diversity in the European wild boar (Sus scrofa). Our final aims were to clarify the influence of present and past climatic conditions, infer the geographical position of glacial refugia, and suggest post-glacial spatial dynamics.Location Europe.Methods D-loop sequences were obtained for 763 individuals from Portugal to western Russia. Phylogenetic, multivariate and interpolation methods were used to describe the genetic and geographical patterns. Climatic suitability during the Last Glacial Maximum (LGM) was predicted using MaxEnt. The effect of present and past suitability on the observed patterns of diversity was evaluated by multiple linear regression. ResultsWe confirmed the existence of a ubiquitous mitochondrial clade in Europe (E1), an endemic clade in Italy (E2) and a few East Asian haplotypes (A), presumably introgressed from domestic pigs. No Near Eastern haplotypes were detected. Genetic divergence was not simply related to geographical distance. A clear south-north decreasing gradient of diversity was observed, with maximum levels in putative glacial refugia. Latitudinal variation in climatic conditions during the LGM was shown to be a good predictor of current genetic diversity. Moreover, an unexpected similarity between Iberia and eastern Europe was observed, while central European populations showed a higher affinity to the Italian gene pool. Main conclusionsThe current distribution of mitochondrial genetic diversity was highly influenced by past climatic events, especially those related to the LGM, and is consistent with a major contribution of the Italian peninsula and the Balkans to the post-glacial recolonization of northern areas. More recent processes, such as restocking and extensive hunting, probably acted at rather local scales, without great impact on the global pattern of mitochondrial diversity.

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The fine-scale genetic structure of mammal populations arises from the social and spatial behaviour of individuals. In wild ungulates gene flow is usually mediated by males, being the dispersing sex. The roe deer Capreolus capreolus represents an exception: males and females disperse in similar proportions as juveniles, but are subsequently mostly sedentary as adults, while mechanisms for inbreeding avoidance are more complex and not fully known. We investigated the seasonal variation in the relationship between genetic relatedness and spatial behaviour in a sample of 69 roe deer, monitored from 2002 to 2010 in a high-density population in Italy. Genetic and spatial analyses, based on individual positions, did not reveal any population structure, neither in the whole sample, nor in the two sexes separately. Our results are coherent with the absence of a sex bias in roe deer dispersal and suggest the existence of a high gene flow across a continuous forest habitat, thus preventing the onset of population structuring at a local scale. We found that genetic relatedness tended to increase with home range proximity, but mostly in winter. Nevertheless, when the extent of overlap between seasonal home ranges with respect to genetic relatedness was considered, males and females seemed to preferably share their home range with relatives of the same sex, reducing the overlap with relatives of the opposite sex during the rutting period. We conclude that home range rearrangements during the breeding season may afford a certain level of spatial segregation between closely related potential mates, thus reducing inbreeding risk.

Patterns of genetic differentiation within and among animal populations might vary due to the simple effect of distance or landscape features hindering gene flow. An assessment of how landscape connectivity affects gene flow can help guide management, especially in fragmented landscapes. Our objective was to analyze population genetic structure and landscape genetics of the native wild boar ( Sus scrofa meridionalis ) population inhabiting the island of Sardinia (Italy), and test for the existence of Isolation‐by‐Distance (IBD), Isolation‐by‐Barrier (IBB), and Isolation‐by‐Resistance (IBR). A total of 393 Sardinian wild boar samples were analyzed using a set of 16 microsatellite loci. Signals of genetic introgression from introduced non‐native wild boars or from domestic pigs were revealed by a Bayesian cluster analysis including 250 reference individuals belonging to European wild populations and domestic breeds. After removal of introgressed individuals, genetic structure in the population was investigated by different statistical approaches, supporting a partition into five discrete subpopulations, corresponding to five geographic areas on the island: north‐west (NW), central west (CW), south‐west (SW), north‐central east (NCE), and south‐east (SE). To test the IBD, IBB, and IBR hypotheses, we optimized resistance surfaces using genetic algorithms and linear mixed‐effects models with a maximum likelihood population effects parameterization. Landscape genetics analyses revealed that genetic discontinuities between subpopulations can be explained by landscape elements, suggesting that main roads, urban settings, and intensively cultivated areas are hampering gene flow (and thus individual movements) within the Sardinian wild boar population. Our results reveal how human‐transformed landscapes can affect genetic connectivity even in a large‐sized and highly mobile mammal such as the wild boar, and provide crucial information to manage the spread of pathogens, including the African Swine Fever virus, endemic in Sardinia.