2018 ESA Annual Meeting (August 5 -- 10)

COS 12-7 - Adaptation of snow leopards to high-altitude via regulatory changes in the hypoxia inducible pathway and potential ecological ramifications

Monday, August 6, 2018: 3:40 PM
254, New Orleans Ernest N. Morial Convention Center
Jan Janecka1, Charlotte Hacker2, Brionna Nelson2, Phylip Auron2, Sree Pulugulla2, William Murphy3, Brian Davis3, Rodney Jackson4, Shafqat Hussain5, Bariusha Munkhtsog6 and Ghulam Muhammad7, (1)Biological Sciences, Duquesne University, Pittsburgh, PA, (2)Duquesne University, (3)Texas A&M University, (4)Snow Leopard Conservancy, (5)Trinity College, (6)Mongolian Academy of Sciences, (7)Project Snow Leopard
Background/Question/Methods

The mechanisms that underpin adaptation to environmental stress enable species to colonize new ecosystems. The structure and function of proteins, physiological constraints, ancestry, and demography all influence adaptive outcomes. Snow leopards occupy high-altitude regions of Central Asia. At high elevation, partial pressures of O2 are low, in turn reducing arterial saturation of blood, limiting aerobic respiration and leading to severe physiological constraints. Previously, the EGLN1 and EPAS1 genes where identified as potentially contributing to adaptation of snow leopards. We thus examined these candidate variants in captive and wild cats and their functional ramifications. Whole genome sequencing of captive snow leopards was performed to determine if these variants were fixed. Next, a high-throughput NGS panel was designed that enabled genotyping-by-sequencing of noninvasively sampled wild populations in moderate-altitude regions of Mongolia (2,000-3,000m abs) and high-altitude regions of Pakistan (>3500m abs). Both EGLN1 and EPAS1 regulate the Hypoxia Inducible Pathway and we thus also compared expression of downstream genes between the snow leopard and tiger, their low-altitude sister species.

Results/Conclusions

We generated 20X-coverage genome data for one snow leopard and 2X-coverage for 4 snow leopards and mapped reads to the draft tiger genome assembly. The sequences for EGLN1 and EPAS1 were extracted and compared. The EGLN1 variant was fixed in the captive snow leopards, whereas two EPAS1 variants exhibited polymorphism. Snow leopards sampled noninvasively in Pakistan and Mongolia were genotyped. We observed a similar pattern as in the captive cats. The EGLN1 variant was fixed in both wild populations. In Pakistan and Mongolia, EPAS1 gene was polymorphic (He = 0.29 and He = 0.23, respectively) at both variants. All three variants in the two candidate genes resulted in nonsynonymous substitutions potentially impacting protein function. We thus extracted RNA from tissues of the snow leopard and tiger and used qPCR to compare relative expression for 5 genes regulated by EGLN1 and EPAS1. A gene that stimulates angiogenesis leading to improved tissue perfusion and oxygen delivery (VEGF) was upregulated in snow leopards. This likely contributes to the adaptive mechanism of snow leopards at high altitude. The retained polymorphism in EPAS1 may enable fine-tuning of the cellular response based on the specific elevational zone occupied or the physiological needs of the animal.