engleski

Adaptive behavior in lizards: an ecological story from biochemical perspective

Lizards are favorable models for studies of animal behavior - diurnal, readily observable, robust, and easily handled, they respond well to hormonal manipulation and display various range of behaviors. P. siculus (Italian wall lizard ; Rafinesque – Schmaltz, 1810) occupies a variety of habitats, including the eastern Adriatic coast with surrounding islands, and undergoes population specific adaptations in morphology, physiology and behavior. Behavior is often the first adaptation that an animal can make in order to cope with changes in its environment. Monoamine neurotransmitters and steroid hormones create a physiological profile that has substantial influence on behavior. Animal behavior has been studied by ethologists, neurobiologists, and behavioral geneticists, often with little overlap. In order to truly understand the regulation of adaptive behavior, it is necessary to combine these three branches of research. Therefore, the main aim of our research is to connect specific adaptive behaviors, driven by environmental influences, with the underlying hormonal and neurological mechanisms along with the genes responsible for their regulation. This concept will be illustrated by the study of the extent to which a different ecological context, in which two populations of the same species (mainland (ML) and island (ISL) P. siculus) reside, shaped adaptive behavior and affected its biochemical make-up. Antipredator behavior and breeding-season plasma testosterone were measured in the field. Additional males were brought to the laboratory and submitted to a battery of behavioral tests and whole-brain monoamine levels measurement. ML population consisted of larger, stronger males of more intensive colors and skin patterns, which displayed significantly higher level of aggressive behavior, indicating that male to male combat is more important on the mainland than on the islands. This could have been mediated by the observed, significantly increased levels of testosterone, which influences sexual and aggressive behavior in males. Although both populations displayed similar flight initiation distance and flight distance, ML lizards remained significantly longer in a hiding place. This indicates similar predation pressure on both locations, but by different predators (birds on ISL vs. cats and snakes on ML), and may be mediated by significantly increased brain concentrations of NA and ADR which play an important role in focusing on potentially dangerous sensory signals from the environment. Our results suggest that monoaminergic and steroid profiles might represent one of the mechanisms through which behavior adjusts to the environment.

Podarcis siculus ; monoamine neurotransmitters ; steroid hormones ; brain ; serum

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