Physiological Ecology Homeostasis: maintenance of a relatively stable internal state under a much wider range of external environmental conditions. Temperature regulation (thermoregulation) Physiological Optima and Tolerance Curves Tolerance limits, optima Net benefit Acclimation Lecture # 11 1 October 2015

Energetics of Metabolism and Movement Ingestion = Assimilation + Egestion Assimilation = Productivity + Respiration Productivity = Growth + Reproduction Ingestion = Egestion + {Respiration + Growth + Reproduction} {Assimilation} Homeotherm versus Poikilotherm Endotherm versus Ectotherm

Body Mass, grams

Log,

Rabbits Moose Beaver Squirrels Racoon

Metabolic Cost of Movement Log,

Metabolic Cost of Movement Log,

Metabolic Cost of Movement Log,

Adaptation and Deterioration of Environment Non-directed (random) changes in either A or B are equally likely to reduce the level of adaptation (d ) when small, but as the magnitude of undirected change increases, the probability of improvement diminishes. Duality of Fisher ’ s model (A and B can be interchanged) Ronald A. Fisher

Water Economy in Desert Organisms Other Limiting Materials Sensory Capacities and Environmental Cues Adaptive Suites Design Constraints

Heat Budgets and Thermal Ecology

Thermoconformers

Passive thermoconformer Nephrurus levis

Active Thermoregulator Ctenophorus isolepis

Active Thermoregulator Ctenophorus isolepis Thermoconformer

Ctenotus skinks

Ctenotus leae Ctenotus piankai