Triturus italicus: Analysis of lateralisation in the courtship behaviour

Abstract

At the population level, male smooth newts (Triturus vulgaris) have a marked bias for left turning during spermatophore transfer behaviour. In a much more basal species of the genus, the Alpine newt, less than 50% of individuals show a significant left‐ or right‐side preference during courtship, whereas no lateral bias is found at population level. To verify whether the smooth newt's lateralised behaviour is a recent (apomorphic) acquisition, the degree of lateralisation during courtship displays occurring in another relatively more basal species (although less basal than T. alpestris), the Italian newt (T. italicus) was investigated. In the latter species, the analysis of the temporal structure of the sequences showed that males significantly utilised the same side during a single courtship sequence. However, 31% of the Italian newts showed a significant left‐ and 46% a right‐side preference. The presence of lateralisation in two relatively ‘primitive’ species (Alpine and Italian newt) at individual level only, with no evidence at population level, and the presence of a bias in a more derived species of the genus (T. vulgaris), support the hypothesis that population‐level lateralisation, in newts, is an independent autoapomorphic evolutionary event that took place in the smooth newt.