Ecology and home range of the Aegean wall lizard (Podarcis erhardii)

摘要: The study of island taxa can help reveal the mechanisms of natural selection when it acts on small, isolated populations. To elucidate how small populations evolve in high-competition, low-predation environments, we examined differences in morphological characteristics, tail autotomy rates, and home range sizes in several populations of Aegean Wall Lizards (Podarcis erhardii; Lacertidae) living on one large-island site and three smallislet sites. While there was relatively little consistent morphological divergence between the study populations, we did observe significantly higher rates of shed and regenerated tails on predator-free, small-island sites, a counterintuitive pattern for a known antipredator defense. Rather than a sign of failed predation events, this pattern is best explained by the fact that tail-shedding can be precipitated by intraspecific aggression and tail cannibalism, which are known to be particularly frequent on small islands. We also found that small-island female lizards, but not males, maintained significantly smaller home ranges than large-island females. Our results indicate that differences in prevailing ecological conditions (most likely reduced food availability and relaxed predation pressure) drive distinct changes in tail shedding rates and home range size in these island lizards.