Parallel behavioral and morphological divergence in fence lizards on two college campuses.

The spread of urban development has dramatically altered natural habitats, modifying community relationships, abiotic factors, and structural features. Animal populations living in these areas must perish, emigrate, or find ways to adjust to a suite of new selective pressures. Those that successfully inhabit the urban environment may make behavioral, physiological, and/or morphological adjustments that represent either evolutionary change and/or phenotypic plasticity. We tested for effects of urbanization on antipredator behavior and associated morphology across an urban-wild gradient in the western fence lizard (Sceloporus occidentalis) in two California counties, Santa Barbara and San Luis Obispo. We compared college campuses in both counties with adjacent rural habitats, conducting field trials that allowed us to characterize antipredator behavior in response to the acute stress of capture. We found notable divergence between campus and rural behavior, with campus lizards more frequently exhibiting diminished escape behavior, including tonic immobility, and lower sprint speeds. Furthermore, campus females had significantly shorter limbs, and while this did not explain variation in sprint speed, those with shorter limbs were more likely to show tonic immobility. We hypothesize that these parallel behavioral and morphological changes on both campuses reflect adjustment to a novel environment involving changes in predation and human presence.

Integrating behaviour into the pace-of-life continuum: Divergent levels of activity and information gathering in fast- and slow-living snakes.

An animal's life history, physiology, and behaviour can be shaped by selection in a manner that favours strong associations among these aspects of an integrated phenotype. Recent work combining animal personality and life-history theory proposes that animals with faster life-history strategies (i.e., fast growth, high annual reproductive rate, short lifespan) should exhibit higher general activity levels relative to those with slower life-history strategies, but empirical tests of within-species variation in these traits are lacking. In garter snakes from ecotypes which are known to differ in ecology, life-history strategy, and physiology, we tested for differences in tongue-flick rate as a measure of information gathering and movement patterns as a measure of general activity. Tongue flicks and movement were strongly positively correlated and both behaviours were repeatable across trials. Snakes from the fast-living ecotype were more active and showed evidence of habituation. The slow-living ecotype maintained low levels of activity throughout the trials. We propose that environmental factors, such as high predation, experienced by the fast-living ecotype select for both increased information-gathering and activity levels to facilitate efficient responses to repeated challenges. Thus, we offer evidence that behaviour is an important component of co-evolved suites of traits forming a general pace-of-life continuum in this system.