Integrating Proximate and Ultimate Causation in the Study of Vertebrate Behavior: Methods Considerations

SYNOPSIS. Methods issues are critical for the integration ofproximate and ultimate explanations of animal behavior. Understandingthat evolution of behavior may begin with changes in sensoryand perceptual systems is a first step. For example, advancesin neurobiology can trigger questions about social behavior.Variation in the size of particular brain areas, such as thehippocampus, can be related to variation in socio-spatial systems.Second, procedures, developed in recent years, provide new avenuesto understand behavior. Hormone assay techniques, such as RIAand ELISA, can be performed on some hormones from urine andfeces collected in the wild. Metabolic measurement, such asthe use of doublylabeled water, make it possible to measureenergy costs under field conditions. Advances in DNA technologiesprovide new perspectives, particularly with regard to measuringreproductive success. Third, current theories in behavior canbe tested with regard to physiological mechanisms; all thatis needed is some ingenuity to design and execute appropriatestudies. These include kin recognition, sex ratio variation,and foraging behavior. Fourth, cross—fertilization betweenlaboratory and field approaches produces new insights regardingbehavior. Organizational effects of hormones have now been exploredin field populations of mice and in domestic swine. Testingaspects of foraging behavior in the laboratory is another example.Fifth, simulation models have been used to produce new questionsabout both proximate and ultimate aspects of behavior. Exploringbehavioral phenomena may involve semi—natural settings.The suitability of semi—natural enclosures for the studyof house mouse behavior has been tested with regard to densityand home range size.