engleski

Sociability and aggressivity of insular Italian wall lizard vary in dependence on ecological conditions

Behavioural traits can allow individuals swift adaptation to novel environmental conditions. Both sociability and aggressivity are known to vary greatly in dependence on population density. On small islands, where populations recurrently reach high densities, individuals usually decrease aggressivity and increase sociability to reduce needless energy expenditure and enhance their fitness. However, on islands where environmental conditions limit the population density, an elevated level of within-population aggressivity can be observed. To further test this phenomenon, we studied lizards in the Lastovo archipelago, where in 1971 Nevo and colleagues performed translocation of Italian wall lizard (Podarcis siculus) from the island of Pod Kopište to the island of Pod Mrčaru. Follow-up studies of that experiment showed that P. siculus populations from those two nearby islets differ in population density and in the number of phenotypic traits. As a part of the Genraliz project, which aimed to determine whether observed phenotypic differences were the result of genetic differences or phenotypic plasticity, we studied sociability and aggressivity of P. siculus populations from both islands. In the spring of 2017, we caught 46 adult lizards from the island of Pod Kopište and 40 adult lizards from the island of Pod Mrčaru and subjected them to behavioural testing after acclimatisation in captivity. Sociability test was performed in a 3-chambered sociability apparatus, while aggressivity was assessed by staging encounters in an open field apparatus and measuring aggressive displays. Preliminary results indicate that the population from Pod Mrčaru, which displays a higher population density in nature, has higher levels of sociability and lower levels of aggression, indicating behavioural adaptation to the new environmental condition.

Behaviour, Ecology

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