27th Annual Meeting and Symposium of the
Desert Tortoise Council, March 22-24, 2002
Abstracts

STUDENT PAPER

Bone Growth Patterns as Indicators of the Evolution and Ecology of Desert Tortoise (Gopherus agassizii) Populations

Amanda J. Curtin
Department of Bioscience and Biotechnology, and School of Environmental Science, Engineering and Policy, Drexel University, Philadelphia, PA 19104

The purpose of this study is to determine whether bone, specifically bone from dead animals, could be used to indicate differences in growth strategies and evolution among wild desert tortoise populations. Growth variation, due to ecological constraints (like diet and climate) and disease, should be visible in the skeletons of both wild and captive desert tortoises. Ecological constraints are known to influence bone growth strategies, and thus life history strategies, in a wide variety of amphibians and reptiles, however few such studies have been done on tortoises. Gopherus agassizii represents a perfect species to investigate, as they are long-lived tortoises, living in a habitat where their survival is extremely dependent on resource availability and quality, which is directly or indirectly influenced by climate (mainly rainfall) and human intervention (e.g. off road vehicle use, grazing and urban expansion). Chronic disease is also a problem in certain populations and because the skeleton can be viewed as a summary of an animal's growth history, I will compare the bone microstructure of diseased and healthy animals to assess whether disease has an impact on growth in general. This will be the first study to attempt to answer questions about tortoise biology across a broad geographic scope and time range, incorporating many populations of wild and captive animals, and has the added advantage of not having to harm, kill or disturb living animals of this threatened species.