Age, courtship and senescence: sexual ornaments are larger in older great crested newts

Abstract

AbstractPatterns of senescence are highly diverse and the underlying mechanisms are controversial. Most studies have focused on endothermic tetrapods, who usually exhibit both actuarial (e.g. the increase in mortality rate with age) and reproductive senescence. However, senescence patterns are less clear in ectothermic vertebrates since these animals exhibit undetermined growth and often increase their reproductive potential throughout their life history. We contribute to this topic by investigating the relationship between age and relative size of sexual ornaments in a urodele amphibian, the great crested newt, Triturus cristatus. We found that the relative sizes of sexual ornaments (crest height, crest area, area of the white caudal spot) were correlated with an individual's age in a population monitored in the wild. These sexual ornaments constitute honest signals reflecting male quality. Thus, the crested newt appeared to undergo negligible reproductive senescence in our population, although further experiments on reproductive success are needed to confirm this hypothesis.