MICROHABITAT USE, RESOURCE PARTITIONING AND ECOLOGICAL SUCCESSION IN A SIZE-STRUCTURED GUILD OF NEWT LARVAE (G TRITURUS, CAUDATA, AMPHIBIA)

Diet and micro-habitat use by larvae of three newt species were compar ed among four ponds which differed in successional stage. Despite grea t feeding overlap, Triturus larvae differed in diet flexibility. The l east flexible species was the largest sized T. cristatus, whereas the broadest niche was observed in the intermediate sized T. alpestris. Su ccessional stage did not influence food overlap. In contrast, micro-ha bitat use varied greatly among species. Whereas T. cristatus larvae we re confined to pond banks, T. alpestris larvae were frequent on pond b ottom and T. helvericus showed an intermediate pattern of distribution . However, such a micro-habitat partitioning was apparent only in site s with an intermediate successional stage. Differences in body size am ong species were related neither to differences in diet nor to micro-h abitat use. Their evolutionary causes are to be sought in selective pr essures acting on the adult stage.