INTEGRATING PROXIMATE AND ULTIMATE CAUSATION IN THE STUDY OF VERTEBRATE BEHAVIOR - METHODS CONSIDERATIONS

Methods issues are critical for the integration of proximate and ultim ate explanations of animal behavior. Understanding that evolution of b ehavior may begin with changes in sensory and perceptual systems is a first step. For example, advances in neurobiology can trigger question s about social behavior. Variation in the size of particular brain are as, such as the hippocampus, can be related to variation in socio-spat ial systems. Second, procedures, developed in recent years, provide ne w avenues to understand behavior. Hormone assay techniques, such as RI A and ELISA, can be performed on some hormones from urine and feces co llected in the wild. Metabolic measurement, such as the use of doubly- labeled water, make it possible to measure energy costs under field co nditions. Advances in DNA technologies provide new perspectives, parti cularly with regard to measuring reproductive success. Third, current theories in behavior can be tested with regard to physiological mechan isms; all that is needed is some ingenuity to design and execute appro priate studies. These include kin recognition, sex ratio variation, an d foraging behavior. Fourth, cross-fertilization between laboratory an d field approaches produces new insights regarding behavior. Organizat ional effects of hormones have now been explored in field populations of mice and in domestic swine. Testing aspects of foraging behavior in the laboratory is another example. Fifth, simulation models have been used to produce new questions about both proximate and ultimate aspec ts of behavior. Exploring behavioral phenomena may involve semi-natura l settings. The suitability of semi-natural enclosures for the study o f house mouse behavior has been tested with regard to density and home range size.