<b>REGULAR ARTICLES / ARTICLES RÉGULIERS</b><p>Size-related predation reduces intramorph competition in paedomorphic Alpine newts

Abstract

Evolutionary theory assumes that facultative paedomorphosis in newts and salamanders is adaptive in allow- ing either a younger age at maturity or resource partitioning between the heterochronic morphs. In newt populations that only take the metamorphic ontogenetic pathway, juveniles are terrestrial and avoid food competition with larvae and breeding adults. In contrast, in populations where paedomorphosis occurs, branchiate newts of all sizes coexist in the aquatic habitats, posing the question of whether intramorph competition exists and its relationship with the evolution of paedomorphosis. We studied size-related predation in such a size-structured community of branchiate Alpine newts (Triturus alpestris) inhabiting a deep alpine lake. Although gape limitation may explain such size-related predation, indi - viduals also exhibited selectivity according to prey size. Amongst small prey that were within the capture range of all newt size classes, smaller newts preyed on smaller items than did larger ones. We assume that such decisions favour the coexistence of different-sized individuals. It is suspected that such size-selective predation on items which are avoided by water-living metamorphs allows the maintenance of facultative paedomorphosis, in favouring resource parti- tioning between morphs. 948 Resume : Chez les tritons et les salamandres, les theories evolutives considerent que la pedomorphose facultative est adaptative en permettant l'acquisition precoce de la maturite sexuelle ou le partage des ressources entre les formes