Display lateralisation in the courtship behaviour of the alpine newt (Triturus alpestris)

Among urodelan amphibians, European newts of the genus Triturus have evolved a complex sequence of displays to the effect of stimulating the female to actively pick up the spermatophore deposited by the male. Courtship is varied, with plenty of potential for asymmetric uses of tails and of asymmetric turns. The analysis of the temporal structure of the behavioural sequences showed that both males and females significantly utilise the same side during a single courtship sequence. Moreover, if an individual prefers to exhibit one side during its lateral displays, then the duration of its displays on that side is longer than the duration of its displays on the other side. The only significantly contralateral display is creep-on. Less than 50% of the alpine newts show a significant left- or right-side preference and no lateral bias at population level was found. At the population level, male Triturus vulgaris showed a marked bias towards left turning after spermatophore deposition, in spite of the existence of both "left-turning" and "right-turning" individuals in the population (Green, 1997). The presence of population biases may be adaptive if it can influence the sensory processes and the motor responses involved in social interactions. In fact, Triturus vulgaris is characterised by a more complex courtship sequence than T. alpestris and by complex male-male interference mechanisms, but no selective advantages were shown for either left- or right-turning males (Green, 1997).