COURTSHIP BEHAVIOR IN THE ALPINE NEWT TRITURUS ALPESTRIS AT TWO DIFFERENT DENSITIES OF MALES

Abstract

The aim of this laboratory experiment was to examine courtship behavior and reproductive success under two different perceived male densities in the Alpine newt (Triturus alpestris). Male behavioral patterns were similar at unbiased and male-biased operational sex ratios (OSR). Although the exhibition of luring behaviors is risky in the presence of other males, no difference in the frequencies of displays was found at the two male densities. Similarly, the responsiveness of females towards males and the success rate of the encounters (i.e., spermatophore transfer) were not explained by the OSR. Our results show that courting Alpine newts do not change their courtship patterns when other males are present and do not interact directly. However they are not necessarily opposed to those of previous experiments showing sexual interference and female aversion in male-biased OSR with possibility of interactions. These observations suggest that the evolution of courtship behavior may not be driven by the risk of sexual interference with other males prior to potential physical contact and that the benefits of breeding regardless of OSR can overcome the risk of competition at male-biased OSR.