Interfaces between biophysical and physiological ecology and the population ecology of terrestrial vertebrate ectotherms

Physiological and biophysical processes interact with a suite of environmental factors to produce important patterns in the population ecology of terrestrial vertebrate ectotherms. We develop a mechanistic approach to understanding the relative contributions of these interactions. Our approach requires a distinction between a life history and a life-history phenotype and allows the incorporation of system-specific trade-offs and constraints in a manner that facilitates the generation of testable predictions for specific populations or sets of populations. We define operant sources of selection and the effects of these averaged over the lifetime of individuals exposed to different environmental factors (available foraging microhabitats, mate availability, preferred egg sites), and synthesize a probabilitistic definition of a life history. We apply this approach to understanding geographic variation in several life-history characters in the saxicolous, iguanid lizard Sceloporus merriami.