Development of homeothermic endothermy is delayed in high altitude native deer mice (Peromyscus maniculatus)

Altricial mammals begin to independently thermoregulate during the first few weeks of postnatal development. In wild rodent populations this is also a time of high mortality (50-95%), making the physiological systems that mature during this period potential targets for selection. High altitude is a particularly challenging environment for small endotherms due to unremitting low O2 and ambient temperatures. While superior thermogenic capacities have been demonstrated in adults of some high altitude species, it is unclear if selection has occurred to survive these unique challenges early in development. We used deer mice (P. maniculatus) native to high and low altitude, and a strictly low altitude species (P. leucopus), raised under common garden conditions, to determine if postnatal onset of endothermy and maturation of BAT is affected by altitude ancestry. We found that the onset of endothermy corresponds with the maturation and activation of brown adipose tissue (BAT) at an equiva...

晚成哺乳动物（Altricial mammals）会在出生后发育的最初数周内，建立独立的体温调节能力。野生啮齿类种群中，这一时期同时也是高死亡率（50%~95%）的高发阶段，使得该时期成熟的生理系统成为自然选择的潜在作用靶标。高海拔环境因持续存在的低氧与低温条件，对小型恒温动物而言极具挑战性。尽管部分高海拔物种的成体已被证实具备卓越的产热能力，但目前尚不明确自然选择是否已作用于发育早期，以帮助个体应对这些独特的生存挑战。本研究选取源自高海拔与低海拔区域的鹿鼠（Peromyscus maniculatus，P. maniculatus）以及严格低海拔的白足鼠（P. leucopus），在同质园环境下开展饲养实验，以此探究出生后恒温能力的启动与棕色脂肪组织（brown adipose tissue, BAT）的成熟是否受海拔起源的影响。我们发现，恒温能力的启动与棕色脂肪组织（BAT）的成熟及激活在等效的