Mountaineering Mice Reveal Secrets of Evolutionary Adaptation

**Teams of mountaineering mice are advancing our understanding of evolutionary adaptation.** A study led by Naim Bautista at the University of Nebraska–Lincoln simulated a 6,000-meter ascent to understand how highland and lowland deer mice adapt to diverse environments. These mice were divided into a control group and an acclimation group, with the latter gradually introduced to higher altitudes over seven weeks. The research demonstrated that highland mice possessed specialized adaptations for coping with low oxygen levels, unlike their lowland counterparts. Notably, highland mice exhibited more efficient breathing, circulatory oxygen transport, and a genetic advantage against pulmonary hypertension, which often affects lowland mammals at high altitudes. This study underscores how specific evolutionary adaptations allow a single species to thrive across varying conditions. The researchers are planning to further explore this with the yellow-rumped leaf-eared mouse, the highest-dwelling mammal found in the Andes. The deer mice study was published in *PNAS* and conducted with collaborators from multiple universities.