Historical and ecological determinants of genetic structure in arctic canids

Abstract

Wolves (Canis lupus) and arctic foxes (Alopex lagopus) are the only canid species found throughout the mainland tundra and arctic islands of North America. Contrasting evolutionary histories, and the contemporary ecology of each species, have combined to produce their divergent population genetic characteristics. Arctic foxes are more variable than wolves, and both island and mainland fox populations possess similarly high microsatellite variation. These differences result from larger effective population sizes in arctic foxes, and the fact that, unlike wolves, foxes were not isolated in discrete refugia during the Pleistocene. Despite the large physical distances and distinct ecotypes represented, a single, panmictic population of arctic foxes was found which spans the Svalbard Archipelago and the North American range of the species. This pattern likely reflects both the absence of historical population bottlenecks and current, high levels of gene flow following frequent long-distance foraging movements. In contrast, genetic structure in wolves correlates strongly to transitions in habitat type, and is probably determined by natal habitat-biased dispersal. Nonrandom dispersal may be cued by relative levels of vegetation cover between tundra and forest habitats, but especially by wolf prey specialization on ungulate species of familiar type and behaviour (sedentary or migratory). Results presented here suggest that, through its influence on sea ice, vegetation, prey dynamics and distribution, continued arctic climate change may have effects as dramatic as those of the Pleistocene on the genetic structure of arctic canid species.

Using genetic methods to investigate dispersal in two badger (Meles meles) populations with different ecological characteristics

“…There have also been a number of recent landscape genetic studies that have shown that dispersal in carnivore species can be habitat specific, that is, individuals have a tendency to disperse preferentially into habitat similar to their natal one (Pilot et al, 2006;Carmichael et al, 2007;Musiani et al, 2007). These studies found a good concordance between geographical boundaries of genetic clusters and ecological factors such as climate and habitat types, as well as diet composition and distribution of prey.…”

The impact of past climate change on genetic variation and population connectivity in the Icelandic arctic fox

“…Previous studies using both mitochondrial and microsatellite markers have demonstrated that the presence of sea ice is the most important factor in explaining arctic fox global population structure [17 -19]. Genetic differentiation between North America, north Greenland and Svalbard is low, implying extensive movement across the sea ice between these areas [17,20]. In fact, the genetic proximity of these areas to Siberia has prompted suggestions that Svalbard may act as a central junction for gene flow across the entire Arctic, mediated by sea ice [17,18].…”

Ecological opportunities and specializations shaped genetic divergence in a highly mobile marine top predator

“…Preferential dispersal towards a habitat similar to one of juvenile life [16] can generate and maintain evolutionary divergence in highly mobile species. While this process may be 'imprinted' in turtles or fishes [17], social learning of foraging techniques for particular prey or habitat may influence dispersal in species having long-term bonds between mothers and calves [4,15]. Individuals may therefore have higher foraging success in familiar habitats where they can use learned hunting techniques, which might enhance their fitness.…”

“…The magnitude of influence of historical versus current processes on population structure can vary among species [13,14] and both can have an important role. For example, genetic differentiation patterns of arctic canids might be linked to historical climatic conditions, social structure and dispersal behaviours [15]. Preferential dispersal towards a habitat similar to one of juvenile life [16] can generate and maintain evolutionary divergence in highly mobile species.…”