Paedogenesis, life history traits and sexual dimorphism: A case study of the smooth newt, Triturus vulgaris, from Pannonia

Abstract

We studied differences in life-history traits, sex ratio and sexual size dimorphism (SSD) between paedotypic and metamorphic smooth newts (Triturus vulgaris) from nearby permanent and temporary ponds. Permanent pond was inhabited by both paedotypic and metamorphic individuals, while in the temporary one only metamorphosed animals existed. The morphological differences were greater between newts from permanent and newts from temporary pond, than between individuals from the same pond. Paedotypic females from permanent pond where paedogenesis occurs were significantly more fecund than metamorphic females from the population with obligate metamorphosis. Also, the former reached sexual maturity significantly earlier than the latter. These differences did not involve a trade-off with other fitness traits, such as life span and survival rate. The extreme intersexual morphometric differentiation was within smooth newts from permanent pond; the highest one was between genders of metamorphic individuals and the smallest one between females and males of the paedotypic individuals. Sex ratio among paedotypes was male-biased, unusual for the smooth newt. while those of metamorphic individuals from both permanent and temporary ponds were much more near parity.