Alternative life-history pathways: Paedomorphosis and adult fitness in European newts (Triturus vulgaris and T. alpestris)

Abstract

Paedomorphs and metamorphs of the smooth newt (Triturus vulgaris) and alpine newt (Triturus alpestris) were compared with respect to body size, age structure, age at sexual maturity, survivorship, and female and male fecundity. Paedomorphs were significantly smaller than metamorphs, except for the alpine newt males. Non-significant differences between morphs in both species in terms of the life span, age of sexual maturity, survival rates and male fecundity were found. The relationships concerning female-fecundity parameters were not so straightforward. The total number of oocytes was significantly higher in smooth-newt paedomorphs, while in the alpine newt the difference was insignificant. When ovary mass was compared, significant differences appeared only in the alpine newt, in favour of metamorphic females. Oviductal egg size was similar in both morphs of T. vulgaris. The maintenance of both life-history strategies in the species studied is discussed in the light of these findings.