Integrating the ecology and physiology of plethodontid salamanders

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Cutaneous gas exchange is "diffusion limited" in most amphibians. Hence plethodontid salamanders, which lack lungs as adults, may be unable to maintain high rates of oxygen uptake at high temperatures, large body sizes, or when oxygen is scarce. However, this physiological constraint apparently does not limit plethodontids ecologically. For example, tropical plethodontids attain large size and experience high temperatures, yet they differ little from temperate zone forms in their respiratory physiology. A far more important consequence of cutaneous respiration for terrestrial plethodontids is that the skin must be moist and permeable if it is used in gas exchange, a constraint that restricts plethodontids to moist microhabitats. Even in moist terrestrial habitats, plethodontids lose water when outside of retreats or burrows. Water loss may restrict foraging and courtship opportunities on all but very wet nights, and plethodontids may abandon surface activity entirely during dry periods. The moist diurnal retreats of most active terrestrial plethodontids may lack sufficient thermal diversity to allow behavioral thermoregulation. Consequently, field body temperatures of plethodontids usually resemble prevailing local climatic conditions, are negatively correlated with elevation, and undergo predictable seasonal variation. Thermal acclimation of metabolism may be instrumental in compensating for this variation in body temperature. The lives of terrestrial plethodontids may consist of long periods of inactivity interspersed with brief periods of activity and energy processing when thermal and hydric conditions permit. Key specializations (low metabolic rate, relatively large energy stores, profound resistance to starvation) may enable plethodontids to survive indefinite periods between unpredictable bouts of feeding. The absence of energetically costly "adaptations" that might allow more regular activity may be a partial explanation of the extraordinarily low energy requirements of plethodontids.

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Reference Code: A83FED01IDUS

Full Citation: Feder, M. E. 1983. Integrating the ecology and physiology of plethodontid salamanders. Herpetologica 39(3): 291-310.

Location: ANIMAL EF: PLETHODON IDAHOENSIS