Production in a Desert Lizard as a Consequence of Prey Availability and Annual Variation in Climate

In water-limited systems such as desert scrub, among year variation in precipitation and temperature should cause commensurate annual variation in the trophic cascade, with strong, dynamic linkage in energy flow up to tertiary and quaternary consumers. The long-nosed leopard lizard Gambelia wislizenii is a prominent diurnal mesopredator of desert scrub ecosystems of western North America. This mesopredator eats primary consumers such as grasshoppers, and secondary and tertiary consumers such as robber flies and lizards. Assuming food is limiting, then food abundance in desert scrub will directly affect this mesopredator’s body condition (mass per unit body length) its ability to grow and reproduce. Hence, it is predicted that marked among-year differences in weather will have similarly marked effects on the abundance of arthropod and lizard prey of G. wislizenii , and will have commensurate effects on individual G. wislizenii and on resulting G. wislizenii population dynamics. For much of the past decade, arthropod and lizard prey abundances have been measured at a single field site in the northern Great Basin desert scrub in mid-summer. These data have been concomitant with focal observations, body measures, and population densities of G. wislizenii . Correlative analyses provide strong inferential support for linkage between climate and productivity among trophic levels in this desert ecosystem.