Primates have adapted to numerous environments and lifestyles but very few species are native to high elevations. Here, we investigated high-altitude adaptations in the gelada (Theropithecus gelada), a monkey endemic to the Ethiopian Plateau. We examined genome-wide variation in conjunction with measurements of haematological and morphological traits. Our new gelada reference genome is highly intact and assembled at chromosome-length levels. Unexpectedly, we identified a chromosomal polymorphism in geladas that could potentially contribute to reproductive barriers between populations. Compared to baboons at low altitude, we found that high-altitude geladas exhibit significantly expanded chest circumferences, potentially allowing for greater lung surface area for increased oxygen diffusion. We identified gelada-specific amino acid substitutions in the alpha-chain subunit of adult haemoglobin but found that gelada haemoglobin does not exhibit markedly altered oxygenation properties compared to lowland primates. We also found that geladas at high altitude do not exhibit elevated blood haemoglobin concentrations, in contrast to the normal acclimatization response to hypoxia in lowland primates. The absence of altitude-related polycythaemia suggests that geladas are able to sustain adequate tissue-oxygen delivery despite environmental hypoxia. Finally, we identified numerous genes and genomic regions exhibiting accelerated rates of evolution, as well as gene families exhibiting expansions in the gelada lineage, potentially reflecting altitude-related selection. Our findings lend insight into putative mechanisms of high-altitude adaptation while suggesting promising avenues for functional hypoxia research.

This dataset includes hematological and morphometric measurements collected from geladas (Theropithecus gelada).

Samples and data collected for this study were obtained from wild geladas in the Simien Mountains National Park (~3,000–4,550 meters above sea level) as part of continuous long-term research conducted by the Simien Mountains Gelada Research Project (SMGRP). Beginning in 2017, the SMGRP has carried out annual capture-and-release campaigns during which animals were temporarily immobilized through remote-distance injection. Briefly, a mixture of ketamine (7.5 mg/kg) and medetomidine (0.04 mg/kg) was injected using darts delivered by a blowpipe (Telinject USA, Inc). Following data and sample collection under the supervision of licensed veterinarians and veterinary technicians, immobilization was reversed with atipamezole (0.2 mg/kg). Animals were monitored by project staff throughout their recovery until they were visibly unimpaired and had returned to their social units. All research was conducted with permission of the Ethiopian Wildlife and Conservation Authority (EWCA) following all laws and guidelines in Ethiopia. Animal procedures were conducted with approval by the Institutional Animal Care and Use Committees (IACUCs) of the University of Washington (protocol 4416-01) and Arizona State University (20-1754R). This research conformed to the American Society of Primatologists/International Primatological Society Code of Best Practices for Field Primatology.

While animals were sedated, we collected morphometric measurements including body mass, chest circumference, and waist circumference. Body mass was measured by a hanging digital scale to 0.05 kg precision. Chest circumference and waist circumference were measured using flexible tape to 0.1 cm precision. Chest circumference was defined as the maximum circumference of the trunk, taken at the maximum anterior projection of the thoracic cage. Waist circumference was defined as the minimum circumference between the pelvis and the thoracic cage.

Whole blood was obtained from all chemically immobilized individuals by femoral venipuncture and collected into K3 EDTA S-Monovette collection tubes (Sarstedt).

We measured hemoglobin concentrations using an AimStrip 78200 digital hemoglobin meter. We loaded 10 µl of venous blood into provided test strips and recorded hemoglobin concentrations (g/dl) using the digital meter. Hematocrit estimates (percentages) were derived from hemoglobin concentrations using the equation: Hct = 2.94 * Hgb [g/dl].

Please cite the linked publication(s) when using this dataset.