Meeting Abstract
36.6 Tuesday, Jan. 5 Climate Change Perturbs Activity Patterns, Social Structure and Population Dynamics of the Lizard Urosaurus ornatus. MILES, D B; Ohio University dmiles2@ohio.edu
Climatic patterns in the arid southwest are characterized by cycles of normal or wet years interspersed by episodes of drought. One signature of global climate change in the southwest is an increase in frequency of El Niño-Southern Oscillation events, warmer temperatures and shifts in rainfall patterns. Climate change may profoundly influence species population dynamics by altering key life history traits, e.g., clutch size, social structure and survival. Urosaurus ornatus is a common lizard found throughout the arid southwest. Both males and females display a polymorphism in throat coloration. Lizards inhabit mesquite trees in the upper bajada habitats of the Rincon Mountains, Arizona; the availability of trees varies with ENSO events due to drought stress. Male morphs are characterized by three mating strategies: dominant, satellite males, and sneaker male. Each male morph varies in dominance status, activity patterns and attractiveness to females. The response to climatic variation is contingent on throat morph. Dominant males have a fitness advantage during wet years by virtue of attracting multiple females. However, survival in drought years is lower for these males relative to survival in wet years. Climatic conditions affects local density and frequency of morphs, the thermal environment as well as resource availability. During drought years, fewer trees are available for lizards raising lizard density per tree. Individuals also have reduced activity times, which limits social interactions, foraging success and energy acquisition, and survival probability. ENSO cycles drive temporal variation in natural selection that differentially favors throat morphs, individual body size and physiological characteristics (e.g., sprint speed and endurance). Differential patterns of natural selection are manifested as changes in adult body size, which in turn results in variation in population density.
