Meeting Abstract

P1.147  Friday, Jan. 4  A costly antipredator behavior in a gradient of predation pressure: tail autotomy in the side blotched lizard Uta stansburiana KUO, C-Y*; IRSCHICK, DJ; Univ. of Massachusetts Amherst; Univ. of Massachusetts Amherst chiyun@bio.umass.edu

The ability to survive predation is one of the most important aspects of organismal fitness. To that end, animals have evolved a diverse array of antipredator traits and strategies that costly to express or maintain. Studies that examined the variation of antipredator traits among populations have shown that the degree to which a costly antipredator trait is expressed is often fine-tuned with the intensity of predation. Autotomy, the voluntary shedding of appendages, is a widespread and extremely costly antipredator behavior that allows an animal to escape even when it is already captured by a predator. The occurrence of autotomy involves two processes. The first is a decision making process where an animal determines whether to autotomize based on the level of physical stimulus on the appendage from predators; the second is the breakage of skeletal structures when the appendage is being separated from the body. No study to date has fully examined whether the ability to autotomize varies among populations across a gradient of predation pressure. In this study, we hypothesize that the facility at which autotomy occurs correlates with predation intensity across conspecific populations. Specifically, we test the following two predictions with a lizard species that has a wide geographical distribution and commonly autotomizes the tails. We predict that individuals experiencing higher predation pressure might (1) autotomize at a lower threshold stimulus, and (2) have to overcome a weaker structural resistance posed by the skeletal elements during the breakage process. Our results will provide insight into whether the facility of autotomy is a product of evolution fine-tuned to the degree of predation intensity.