干旱区生态环境知识资源中心

Background: Grey wolves (Canis lupus) are a widespread, Holarctic species distributed across a wide variety of habitats, including deserts, dry plains, boreal forests, and the high arctic. They are generalist carnivores, feeding on a wide variety of species throughout their range. Wolves also disperse readily, with multiple records of over 1000 km. Despite this, surprising examples of differentiation between contiguous wolf populations have been described.

Questions: How can population differentiation arise and be maintained in a continuously distributed, generalist species? How might this structure impact evolution and conservation?

Data: Previously published genetic, morphological, and ecological data from ancient, historic, and modern populations of grey wolves from across their distribution.

Results: Genetic differentiation of wolf populations is tightly associated with habitat characteristics. This requires that dispersing wolves primarily disperse within their natal habitat. As wolves increase their range to occupy new areas, these tend to be colonized by small numbers of wolves often occupying similar habitats. The new arrivals quickly adapt to the new conditions and may be able to exclude other potential immigrating wolves. This limitation in the admixture between populations implies that populations in vanishing habitats (i.e. due to climate change or land use change) are likely to disappear with the habitats, resulting in the loss of locally adapted ecotypes. This cycle of repeated isolation and extinction has led to the observed low level of genetic diversity both within populations and within the species, lower than for other widespread canids.

Conclusions: Structure in wolf populations is generated through ’isolation by environment’. This implies that the genetic diversity is more partitioned than expected within the distribution range of wolves, leading to a decrease in the effective population size and evolutionary potential of wolves within a given habitat, a threat when facing environmental changes. This has resulted in a pattern of local extinctions and reduced genetic variation.