Age and size at metamorphosis of half-sib larvae of Salamandra infraimmaculata born in the laboratory and raised singly under three different food regimes

Salamandra infraimmaculata is an endangered amphibian urodele species inhabiting an unpredictable xeric environment at the edge of its zoogeographic distribution on Mt. Carmel, Israel. This area is characterized by early October rains of short duration forming rock pools where this salamander breeds. Since these shallow ponds dry out rather soon, the larvae have limited time to develop and metamorphose. It is of great importance that they reach this stage of development quickly and attain the largest size possible. This study examined metamorphosis under experimental conditions using half-sib larvae of the same age raised singly under different food regimes without any stress of density. It was found that age, mass and length at metamorphosis regressed significantly with food regimes when salamander larvae were raised singly. Thus, a significant difference in age and mass at metamorphosis was found between larvae raised singly on three food regimes. Age was least, and both mass and length were greatest when larvae were fed `ad-libitum'. Minimal and maximal age at metamorphosis increased significantly and mass decreased significantly as food became scarcer. Consequently, metamorphosis appears to be affected by food resources when density was not a factor. The significance of this finding is discussed.