Abstract
Understanding population genetic structure of climate‐sensitive herbivore species is important as it provides useful insights on how shifts in environmental conditions can alter their distribution and abundance. Herbivore responses to the environment can have a strong indirect cascading effect on community structure. This is particularly important for Royle's pika (Lagomorpha: Ochotona roylei), a herbivorous talus‐dwelling species in alpine ecosystem, which forms a major prey base for many carnivores in the Himalayan arc. In this study, we used seven polymorphic microsatellite loci to detect evidence for recent changes in genetic diversity and population structure in Royle's pika across five locations sampled between 8 and 160 km apart in the western Himalaya. Using four clustering approaches, we found the presence of significant contemporary genetic structure in Royle's pika populations. The detected genetic structure could be primarily attributed to the landscape features in alpine habitat (e.g., wide lowland valleys, rivers) that may act as semipermeable barriers to gene flow and distribution of food plants, which are key determinants in spatial distribution of herbivores. Pika showed low inbreeding coefficients (F IS) and a high level of pairwise relatedness for individuals within 1 km suggesting low dispersal abilities of talus‐dwelling pikas. We have found evidence of a recent population bottleneck, possibly due to effects of environmental disturbances (e.g., snow melting patterns or thermal stress). Our results reveal significant evidence of isolation by distance in genetic differentiation (F ST range = 0.04–0.19). This is the first population genetics study on Royle's pika, which helps to address evolutionary consequences of climate change which are expected to significantly affect the distribution and population dynamics in this talus‐dwelling species.
Highlights
Over the past century, climate has been changing at a faster pace in alpine habitats than in other ecosystems, for which many species must either adapt or migrate to areas with optimal conditions (Naftz et al, 2002; Shrestha, Gautam, & Bawa, 2012)
We used 64 nuclear microsatellite loci which have previously been used in population genetic studies of other lagomorph species and for other pika species
The Royle’s pika populations exhibited similar levels of genetic diversity (0.57) to those observed in other studies on talus‐dwelling
Summary
Climate has been changing at a faster pace in alpine habitats than in other ecosystems, for which many species must either adapt or migrate to areas with optimal conditions (Naftz et al, 2002; Shrestha, Gautam, & Bawa, 2012). The Royle’s pika (Ochotona roylei) is a widespread small herbivore, occupying much of the Himalayan arc—from northwestern Pakistan to India (Jammu and Kashmir, Himachal Pradesh, and Uttarakhand), Nepal, and adjacent Tibet (Bhattacharyya & Smith, 2018) and in‐ habits rocky boulder or talus habitat between 2,400 and 5,200 m elevation. It is an asocial mammal (Bhattacharyya & Smith, 2018, Figure 1) and, unlike other talus‐dwelling pika species (e.g., American pika Ochotona princeps, Collared pika Ochotona collaris), does not ex‐ hibit haying activity to store winter food resources (Bhattacharyya, Adhikari, & Rawat, 2013). The Royle’s pika play a cru‐ cial role in trophic interactions in alpine habitat—pikas are the major prey base for many carnivores as well as influencing native plant community structure (Aryal, Sathyakumar, & Kreigenhofer, 2010; Bhattacharyya et al, 2013, 2018 ; Bhattacharyya, Dutta, Adhikari, & Rawat, 2015)—their disappearance can have a significant negative cascading effect on overall ecosystem functioning (Gilg, Sittler, & Hanski, 2009; Tylianakis, Didham, Bascompte, & Wardle, 2008)
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