Why do mountain mice respond differently despite genetic similarity?

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Mountain Mice Possess Unique Genetic Adaptations for Hypoxia and Respiration

Despite being genetically similar to their lowland counterparts, Andean leaf-eared mice inhabiting high altitudes exhibit distinct genetic variations that confer remarkable adaptations for survival in low-oxygen environments. These adaptations include a specific gene linked to hypoxia tolerance, similar to that found in Tibetan populations, and a unique physiological response to oxygen deprivation. Rather than increasing red blood cell production, these mice accelerate their breathing rate and rely on a modified enzyme to manage the consequences of this rapid respiration.
Distinct Genes Facilitate Hypoxia Tolerance

Mice residing at extreme altitudes possess a set of distinct genes that differentiate them from those living at lower elevations. Among these is a gene identified for its role in adapting to hypoxia, a condition of oxygen deprivation. This genetic divergence allows the high-altitude mice to better cope with the thin air found in the Andes, a characteristic that has previously been observed in human populations adapted to high-altitude living, such as those in Tibet.
Respiration and Enzyme Modification Counteract Oxygen Scarcity

Unlike many mammals that increase their red blood cell count to enhance oxygen uptake in low-oxygen conditions, the Andean leaf-eared mouse employs a different strategy. These mice breathe more rapidly to compensate for the reduced oxygen availability. To mitigate potential adverse effects associated with this accelerated breathing, such as respiratory alkalosis, the animal utilizes a modified enzyme. This enzymatic adaptation is crucial for maintaining physiological balance despite the increased respiratory rate.
Evolutionary Pressures Drive Unique Adaptations

The broad elevational distribution of the Andean leaf-eared mouse, spanning from sea level to altitudes exceeding 6,700 meters, indicates significant evolutionary pressures shaping its resilience. The genetic similarities between high- and low-altitude populations suggest a relatively recent divergence or ongoing gene flow, yet the distinct genetic makeup of the mountain-dwelling mice highlights their specialized adaptations. These include not only the mechanisms for dealing with hypoxia but also the ability to maintain body heat in frigid environments and metabolize scarce, toxic plants, underscoring the remarkable adaptability of this species to extreme conditions.

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Why do mountain mice respond differently despite genetic similarity?

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