Utilization of prenatal patients as a tracer for a patient education needs assessment

The pattern of resource utilization exhibited by a species is usually considered to have resulted from the interaction of three parameters: : resource availability, individual preference, and degree of competition. Studies that I conducted on an iguanid lizard concerning (1) the effect of thermoregulation on diel activity, (2) the relationship between population density and resource use, and (3) the dependence of social structure on local population density and resource availability have shown that other factors may influence this pattern as well.

These studies were completed on a population of Sceloporus jarrovi inhabiting a mixed oak-riparian woodland area in southeastern Arizona. The influence of thermoregulatory factors on lizard activity was determined by temporal censuses during which light condition, air and substrate temperature and lizard cloacal temperature were collected for each active animal.

Although adults and juveniles were found to exhibit similar thermoregulatory strategies, the adults did have a significantly lower rate of heat exchange and thus were comparatively inefficient in maintaining body temperatures within a favorable range during the hotter afternoon hours. They were thus restricted in the time they could spend in sunlight and were forced to spend more time in the shade. They probably found it energetically costly to be active at all in the afternoon. These differences were reflected in temporal partitioning by S. Jarrovi age classes, with adults being largely active in the morning and midday, while juveniles were active throughout the day.

The influence of population density on resource utilization was examined through manipulation of small enclosed populations of adult S. Jarrovi Densities were varied from normal to 4X normal. During censuses conducted throughout the day, the following data were recorded: locations of individuals, substrate association, light condition, perch height, and perch diameter. The data were summarized for individual lizards and examined using stepwise multiple discriminant analysis. The differences observed among the populations centered along thermal and perch gradients. Animals in the highest density enclosure were active throughout the day and spent more time in the shade and less in the sun, probably due to thermoregulatory constraints. Perch site selection shifted, at high density, away from the normallypreferred rock substrate to log and ground substrates. In addition, since no significant differences in weight changes were observed among the different density levels, it was probable that the animals altered their use of food as well. This, however, is speculative as no stomach contents were examined.

The exhibition of social strategies (e.g. territorial, hierarchical, or scramble behaviors) appropriate to specific environmental contexts is a means by which individuals can maximize their fitness since these behavior patterns have specific costs and benefits associated with them. Following this line of thought, a predictive model was constructed to delineate a possible energetic basis for social structure. Model results

viii indicate that social structure should be more sensitive to changes in local population density than to changes in resource availability because most of the energetic costs occur during intraspecific encounters.

This prediction was tested using small enclosed populations of adult S. Jarrovi. A hierarchical social structure was observed at high densities in contrast to the territorial structure characteristic of this species at normal density. These animals were not observed to switch back to a territorial structure with food supplementation. Both results were consistent with the model's predictions.

Behavioral flexibility is a prominent feature of this species as well as other vertebrates. Its prevalence indicates that the monitoring of and adjustment to environmental changes yields significant benefits to individuals, perhaps permitting survival and reproduction under all but the most severe environmental conditions.