Sexual strategies in the newts Triturus cristatus and Triturus marmoratus

Courtship display characteristics are described and compared for the newts Triturus cristatus and T. marmoratus and patterns of male competitive behaviour are recognized. In interpreting the data, the operational sex ratio has to be taken into account, which was highly biased towards males in both species, more in T. marmoratus than in T. cristatus. When sexual active, males of cristatus had more encounters than males of marmoratus, whereas the latter spent more time residing mating places. The male’s display towards a female differed in time structure, variability and in behaviour characteristics. T. marmoratus display follows a fixed pattern; males succeeded better in restraining a female than males cristatus did. Courting males cristatus allowed other males to intrude. Malemale encounters were longer and playful in T. cristatus, more violent in T. marmoratus. Comparison with data from the literature indicates that courtship of T. marmoratus has more features in common with that of T. vittatus than it has with the courtship of T. cristatus. It is suggested that in the course of evolution T. marmoratus adopted a strategy of Sexual Defense by means of territoriality and overt fighting, whereas T. cristatus in contrast adopted a strategy of Sexual Interference by female mimicry. Male display components that played a major role during the adaptation of competitive strategy are identified as the “whip” behaviour in T. marmoratus and the “rocking” behaviour in T. cristatus.