Experimental study of dispersal behaviour in a wall lizard species (Podarcis sicula) (Sauria Lacertidae)

Abstract

Movement behaviour and dispersal are key processes in biology because they represent a basic phase of the individual life-cycle with spin-offs for population dynamics, genetics and biogeography. Experimental studies have shown that the dispersal rate increases with density for a variety of taxa. Here we investigate the ecological aspects of animal movement and dispersal in a wall lizard species (Podarcis sicula), evaluating the short-term effects of increasing population density and individual conditions. The individual attitude on movement is assessed by comparing immigration between two alternative scenarios of augmentation (moderate starting density) and colonisation (high starting density) by using a connected semi-natural enclosure system. The main result of our study was that the patch density influenced the dispersal activity in the study species. Moreover, the movement rate between patches was sex-biased (higher in males), influenced by tail status, but not dependent upon body size and condition. The patch density drove the movement activity in the studied lizards (augmentation design), but there were also factors at individual level influencing the propensity to move (sex and tail status). In the studied lizard, individual decisions to leave a patch and settle in a new one are both condition-dependent – which means that individuals rely on a set of external cues to adjust their dispersal tactics – and phenotype-dependent – which means that dispersal propensity correlates with a suite of phenotypic traits.