Conservation implications of the evolutionary history and genetic diversity hotspots of the snowshoe hare

Abstract

With climate warming, the ranges of many boreal species are expected to shift northward and to fragment in southern peripheral ranges. To understand the conservation implications of losing southern populations, we examined range-wide genetic diversity of the snowshoe hare (Lepus americanus), an important prey species that drives boreal ecosystem dynamics. We analysed microsatellite (8 loci) and mitochondrial DNA sequence (cytochrome b and control region) variation in almost 1000 snowshoe hares. A hierarchical structure analysis of the microsatellite data suggests initial subdivision in two groups, Boreal and southwestern. The southwestern group further splits into Greater Pacific Northwest and U.S. Rockies. The genealogical information retrieved from mtDNA is congruent with the three highly differentiated and divergent groups of snowshoe hares. These groups can correspond with evolutionarily significant units that might have evolved in separate refugia south and east of the Pleistocene ice sheets. Genetic diversity was highest at mid-latitudes of the species' range, and genetic uniqueness was greatest in southern populations, consistent with substructuring inferred from both mtDNA and microsatellite analyses at finer levels of analysis. Surprisingly, snowshoe hares in the Greater Pacific Northwest mtDNA lineage were more closely related to black-tailed jackrabbits (Lepus californicus) than to other snowshoe hares, which may result from secondary introgression or shared ancestral polymorphism. Given the genetic distinctiveness of southern populations and minimal gene flow with their northern neighbours, fragmentation and loss of southern boreal habitats could mean loss of many unique alleles and reduced evolutionary potential.

Population genetics analysis of the Nujiang catfish Creteuchiloglanis macropterus through a genome-wide single nucleotide polymorphisms resource generated by RAD-seq

“…During the middle and late Pleistocene, glacial and interglacial periods caused repeated changes in the distributions of endemic fish on the Tibetan Plateau 29,30 . However, no study has investigated the population genetics and demographic history of C. macropterus .…”

The hidden history of the snowshoe hare, Lepus americanus: extensive mitochondrial DNA introgression inferred from multilocus genetic variation

“…Cheng et al . () also show that the Pacific Northwest population of L. americanus possesses an mtDNA lineage that is more closely related to that of the black‐tailed jackrabbit, L. californicus . This pattern of mtDNA divergence may result from secondary introgression following interspecific hybridization, as often described among species of hares, or from incomplete lineage sorting.…”

Eco‐evolution on the edge during climate change

“…Figure 1. Species that persisted in warm-margin refugia during past climate changes might also retain higher genetic variation (Hampe and Petit 2005, Cheng et al 2014, Pironon et al 2017). The horizontal lines show the boundary between suitable and unsuitable climate (blue dotted), the range boundary with evolution (red solid) and the range boundary without evolution (grey dashed).…”