Abstract
Developmental plasticity can elicit phenotypic adjustments that help organisms cope with environmental change, but the relationship between developmental plasticity and plasticity in adult life (e.g., acclimation) remains unresolved. We sought to examine developmental plasticity and adult acclimation in response to hypoxia of aerobic capacity (V̇O2max) for thermogenesis in deer mice (Peromyscus maniculatus) native to high altitude. Deer mice were bred in captivity and exposed to normoxia or one of four hypoxia treatments (12 kPa O2) across life stages: adult hypoxia (6–8 weeks), post-natal hypoxia (birth to adulthood), life-long hypoxia (before conception to adulthood), and parental hypoxia (mice conceived and raised in normoxia, but parents previously exposed to hypoxia). Hypoxia during perinatal development increased V̇O2max by a much greater magnitude than adult hypoxia. The amplified effect of developmental hypoxia resulted from physiological plasticity that did not occur with adult hypoxia – namely, increases in lung ventilation and volume. Evolved characteristics of deer mice enabled developmental plasticity, because white-footed mice (P. leucopus; a congener restricted to low altitudes) could not raise pups in hypoxia. Parental hypoxia had no persistent effects on V̇O2max. Therefore, developmental plasticity can have much stronger phenotypic effects and can manifest from distinct physiological mechanisms from adult acclimation.
Highlights
Developmental plasticity is the process by which phenotypes are altered by the early life environment, and is often viewed to be irreversible and underpinned by distinct mechanisms from phenotypic plasticity in adult life
Whereas lowland mice exhibited a modest increase in total ventilation after adult hypoxia acclimation compared to normoxic controls (Figure 3D), this change was driven by higher breathing frequency and no change in tidal volume
Developmental plasticity can help organisms respond to environmental change, but for many performance traits that are critical to fitness, we still have a poor understanding of the importance and life-stage specificity of developmental plasticity and how it relates to reversible acclimation during adulthood
Summary
Developmental plasticity is the process by which phenotypes are altered by the early life environment, and is often viewed to be irreversible and underpinned by distinct mechanisms from phenotypic plasticity in adult life (e.g., acclimation; Burggren and Reyna, 2011; Moczek et al, 2011; Burggren, 2020). The cold and oxygen-depleted (hypoxic) environment at high altitude requires that endotherms sustain high rates of O2 consumption for heat generation (thermogenesis) and locomotion, while facing a diminished O2 supply. This is challenging for mammals of small body size, which face greater demands for thermogenesis as a result of a larger surface area to volume ratio. Small mammals that are native to high altitude provide an opportunity to examine how environmental effects across multiple distinct life stages – both early developmental and adult – might interactively affect complex adult phenotypes
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