Consequences of metamorphosis for the locomotor performance and thermal physiology of the newt Triturus cristatus.

During metamorphosis, most amphibians undergo rapid shifts in their morphology that allow them to move from an aquatic to a more terrestrial existence. Two important challenges associated with this shift in habitat are the necessity to switch from an aquatic to terrestrial mode of locomotion and changes in the thermal environment. In this study, I investigated the consequences of metamorphosis to the burst swimming and running performance of the European newt Triturus cristatus to determine the nature and magnitude of any locomotor trade-offs that occur across life-history stages. In addition, I investigated whether there were any shifts in the thermal dependence of performance between life-history stages of T. cristatus to compensate for changes in their thermal environment during metamorphosis. A trade-off between swimming and running performance was detected across life-history stages, with metamorphosis resulting in a simultaneous decrease in swimming and increase in running performance. Although the terrestrial habitat of postmetamorphic stages of the newt T. cristatus experienced greater daily fluctuations in temperature than the aquatic habitat of the larval stage, no differences in thermal sensitivity of locomotor performance were detected between the larval aquatic and postmetamorphic stages. The absence of variation across life-history stages of T. cristatus may indicate that thermal sensitivity may be a conservative trait across ontogenetic stages in amphibians, but further studies are required to investigate this assertion.