Developing Physiological Diagnostics for the Desert Tortoise

Science Center Objects

The Mojave desert tortoise is listed as “threatened” under the Endangered Species Act and faces threats from habitat loss, predators, and disease. Drs. Lizabeth Bowen and A. Keith Miles with WERC are designing new methods to determine the type and influence of stressors present in the environment for the tortoise and other wildlife.

The desert tortoise (Gopherus agassizii) inhabits the Mojave Desert in the southwestern United States. Following dramatic declines in many desert tortoise populations, the U.S. Fish and Wildlife Service listed the tortoise as a Threatened species under the Endangered Species Act and set aside critical habitat within the Mojave Desert. Researchers have suggested numerous causes for the drop in numbers, including changes in the environment, habitat loss, predation, and disease. However, the primary drivers behind the desert tortoise’s decline are difficult to pinpoint.

Desert tortoises are vulnerable to many ecological and environmental stressors. Linking sensitive, molecular-based diagnostic tests to the health of desert tortoises could potentially serve as an indicator of overall ecosystem health and stability. As an addition to existing diagnostic methods, Drs. Bowen and Miles have developed the first leukocyte gene transcription biomarker panel for the desert tortoise. This new tool enhances the ability to identify specific environmental conditions potentially linked to declining animal health. Blood leukocyte transcript profiles have the potential to identify physiologically stressed animals in lieu of clinical signs. For desert tortoises, the gene transcript profile includes a combination of immune or detoxification response genes influenced by biological or physical injury and consequently provide information on the type and magnitude of stressors present in the animal’s habitat.