engleski

Differences in morphology, performance and behaviour between recently diverged populations of Podarcis sicula mirror differences in predation pressure

We investigated the possible role of variation in predation pressure in the phenotypic divergence of two island populations of the Italian wall lizard, Podarcis sicula. In 1971, ten adult specimens from the island of Pod Kopiste (Adriatic Sea, Croatia) were transported to the island of Pod Mrcaru, 3.5 km east, where they founded a new population. Although the two islands resemble each other in general physiognomy (size, elevation, microclimate) and in the absence of terrestrial predators, lizards from the newly established population are now on average larger and have shorter hind limbs. They also exhibit lower maximal sprint speed as measured on a racetrack, and fatigue faster when chased in a torus track. In the field, lizards from the original population of Pod Kopiste respond to a simulated predatory attack by fleeing at larger approach distances and by running further from the predator than lizards from Pod Mrcaru. These changes in morphology, behaviour and performance may result from the relaxed predation intensity on the latter island. Our analysis of the structural features of the microhabitats suggests that the vegetation on Pod Mrcaru offers more protection to lizards. Also, plasticine models of lizards, laid out on the islands, less often exhibited signs of being attacked by birds on Pod MrČaru than on Pod Kopiste. Our findings provide an example of how changes in (possibly a single) environmental factor may simultaneously produce responses in behaviour, morphology and whole-animal physiology, and this on a surprisingly small spatial and temporal scale.

Vertebrata; Reptilia; Sauria; Podarcis sicula; Predation; Performance; Morphology

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