The role of geography, environment, and genetic divergence on the distribution of pikas in the Himalaya

Abstract

Pikas (Ochotona Link, 1795) are high‐altitude specialist species making them a useful bioindicator species to warming in high‐altitude ecosystem. The Himalayan Mountains are an important part of their range, supporting approximately 23%–25% of total pika species worldwide, yet we lack basic information on the distribution patterns. We combine field‐based surveys with genetics‐based identification and phylogeny to identify differences in species‐environment relationships. Further, we suggest putative evolutionary causes for the observed niche patterns. Location Himalayan high‐altitude region. Methods We sampled 11 altitudinal transects (ranging from ~2,000 to 5,000 m) in the Himalaya to establish occurrence records. We collected 223 species records using genetic analyses to confirm species' identity (based on some invasive and mostly noninvasive biological samples). Niche and geographic overlap were estimated using kernel density estimates. Results Most pikas in the Himalaya span wide elevation ranges and exhibit extensive spatial overlap with other species. However, even in areas of high species diversity, we found species to have a distinct environmental niche. Despite apparent overlapping distributions at broad spatial scales, in our field surveys, we encountered few cases of co‐occurrence of species in the sampled transects. Deeply diverged sister‐species pair had the least environmental niche overlap despite having the highest geographic range overlap. In contrast, sister‐species pair with shallow genetic divergence had a higher environmental niche overlap but was geographically isolated. We hypothesize that the extent of environmental niche divergence in pikas is a function of divergence time within the species complex. We assessed vulnerability of species to future climate change using environmental niche and geographic breadth sizes as a proxies. Our findings suggest that O. sikimaria may be the most vulnerable species. Ochotona roylii appears to have the most unique environmental niche space, with least niche overlap with other pika species from the study area.

High-altitude rodents have abundant collaterals that protect against tissue injury after cerebral, coronary and peripheral artery occlusion

“…93 However, our above M.musculus findings indicate once again that more than just these two conspecific pair would have to be studied to reach a firm conclusion. Examining additional highaltitude evolved species such as pikas 94,95 would also strengthen our conclusions, although these and many other high-altitude evolved species, like guinea pigs, lack a lowland comparator strain. As well, the above studies would be faced with the logistics of wild capture in remote regions.…”

“… 1 , 11 , 12 , 17 , 32 , 55 ,96 Such studies could add collateral extent to the list of physiological mechanisms that contribute to hypoxia adaptation by improving oxygen transport and distribution of blood flow. 52 , 53 , 93 – 95 Investigation could also be extended to populations affected by sickle cell disease and thalassemia. Identifying genetic factors that determine collateral extent in high-altitude animal and human populations may help clarify differences in susceptibility to ischemic diseases and lead to new therapeutic approaches.…”

Geography vs. past climate: the drivers of population genetic structure of the Himalayan langur

“…It extends 2500 kms in length from west to east and its width varies between 350 km in the west and 150 km in the east [ 49 ]. Given these, there are very few studies testing the effect of such a complex topography and climatic fluctuations on the distribution and demography of species found in the Himalayas [ 28 , 29 , 50 , 51 ]. Himalayan langur, (Primate: Colobinae) is a widely distributed alloprimate found in most parts of the Himalayas.…”

A rare camera trap record of the Hispid Hare Caprolagus hispidus from Dudhwa Tiger Reserve, Terai Arc Landscape, India

“…These mammals have been known to inhabit all continents except Antarctica (Chapman & Flux 2008). In India, members of this group are found in a variety of landscapes ranging from high elevation regions of Ladakh and Arunachal Pradesh to tall grassland habitats of the Himalayan foothills (Aryal & Yadav 2019;Dahal et al 2020;Maheswaran 2020). One among these, the Hispid Hare Caprolagus hispidus (Pearson, 1839) is a member of the Leporidae family, and is characterized by its small ears, long fore legs and very short hind legs.…”