Genetic Evidence for Restricted Dispersal along Continuous Altitudinal Gradients in a Climate Change-Sensitive Mammal: The American Pika

Abstract

When faced with rapidly changing environments, wildlife species are left to adapt, disperse or disappear. Consequently, there is value in investigating the connectivity of populations of species inhabiting different environments in order to evaluate dispersal as a potential strategy for persistence in the face of climate change. Here, we begin to investigate the processes that shape genetic variation within American pika populations from the northern periphery of their range, the central Coast Mountains of British Columbia, Canada. At these latitudes, pikas inhabit sharp elevation gradients ranging from sea level to 1500 m, providing an excellent system for studying the effects of local environmental conditions on pika population genetic structure and gene flow. We found low levels of neutral genetic variation compared to previous studies from more southerly latitudes, consistent with the relatively recent post-glacial colonization of the study location. Moreover, significant levels of inbreeding and marked genetic structure were detected within and among sites. Although low levels of recent gene flow were revealed among elevations within a transect, potentially admixed individuals and first generation migrants were identified using discriminant analysis of principal components between populations separated by less than five kilometers at the same elevations. There was no evidence for historical population decline, yet there was signal for recent demographic contractions, possibly resulting from environmental stochasticity. Correlative analyses revealed an association between patterns of genetic variation and annual heat-to-moisture ratio, mean annual precipitation, precipitation as snow and mean maximum summer temperature. Changes in climatic regimes forecasted for the region may thus potentially increase the rate of population extirpation by further reducing dispersal between sites. Consequently, American pika may have to rely on local adaptations or phenotypic plasticity in order to survive predicted climate changes, although additional studies are required to investigate the evolutionary potential of this climate change sensitive species.

Novel genomic resources for a climate change sensitive mammal: characterization of the American pika transcriptome

“…Previous work in Tweedsmuir Park has characterized neutral and adaptive genetic variation in O . princeps along three elevational transects [13]. Tissue collection in the current study focussed on ‘The Hill’ site, which has an elevational cline from 301 m (low elevation site) to 1433m (high elevation site) above sea level.…”

“…princeps . We generated transcriptome-wide sequence data for pooled cDNA libraries from high (1400 m) and low (300 m) elevation sites along a previously established elevation gradient in the British Columbia (BC) Coast Mountains [13]. The resulting high coverage contigs and large suite of SNP loci represent novel genomic resources for studying pika ecology, behaviour and population history, and enable direct investigations of potential biotic responses to changing environments.…”

Microrefuges and the occurrence of thermal specialists: implications for wildlife persistence amidst changing temperatures

“…Pikas are sensitive to ambient temperatures [30,31], with hyperthermia and death resulting after brief exposures to ambient temperatures > 28°C [32]. Pikas can exploit favorable temperatures in interstitial spaces between rocks (hereafter talus), and are one of the only vertebrates active year-round in montane systems, where some of the most extreme climatic changes are occurring [30,31].…”

“…Pikas can exploit favorable temperatures in interstitial spaces between rocks (hereafter talus), and are one of the only vertebrates active year-round in montane systems, where some of the most extreme climatic changes are occurring [30,31]. Additionally, pikas are habitat specialists with relatively low fecundity and dispersal capability [30,32]. As a result, immediate responses to changing conditions may be essential to the species' persistence.…”

Are American Pikas (<em>Ochotona princeps</em>) in the Canadian Rockies vulnerable to climate change?

“…Most research on the American Pika's adaptations to climate change has been done in the United states; Cana dian studies are limited to MacArthur and Wang (1973, 1974), henry et al (2012a, and henry and Rus sello (2013). the Canadian Rockies can generally be characterized as having more contiguous high-elevation areas, cooler temperatures, longer winters, and more persistent snowpacks than in the United states.…”