Abstract:
Pikas (Lagomorpha: Ochotonidae) are small mouse-like lagomorphs. To investigate their adaptation to different ecological environments during their dispersal from the Qinghai-Xizang (Tibet) Plateau (QTP), we collected 226 pikas and measured 20 morphological characteristics and recorded habitat information. We also sequenced the genome of 81 specimens, representing 27 putative pika species. The genome-wide tree based on 4 090 coding genes identified five subgenera, i.e.,
Alienauroa,
Conothoa,
Lagotona,
Ochotona, and
Pika, consistent with morphometric data. Morphologically,
Alienauroa and
Ochotona had similar traits, including smaller size and earlier divergence time compared to other pikas. Consistently, the habitats of
Alienauroa and
Ochotona differed from those of the remaining subgenera. Phylogenetic signal analysis detected 83 genes significantly related to morphological characteristics, including several visual and hearing-related genes. Analysis of shared amino acid substitutions and positively selected genes (PSGs) in
Alienauroa and
Ochotona identified two genes, i.e., mitochondrial function-related
TSFM (p.Q155E) and low-light visual sensitivity-related
PROM1 (p.H419Y). Functional experiments demonstrated that TSFM-155E significantly enhanced mitochondrial function compared to TSFM-155Q in other pikas, and PROM1-419Y decreased the modeling of dynamic intracellular chloride efflux upon calcium uptake.
Alienauroa and
Ochotona individuals mostly inhabit different environments (e.g., subtropical forests) than other pikas, suggesting that a shift from the larger ancestral type and changes in sensory acuity and energy enhancement may have been required in their new environments. This study increases our understanding of the evolutionary history of pikas.
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