Changes in food availability mediate the effects of temperature on growth, metamorphosis and survival in endangered yellow spotted mountain newt: implications for captive breeding programs

The effects of temperature and food levels on body size, growth rate, time to metamorphosis and survival were studied in larval and post-metamorphic juvenile endangered yellow spotted mountain newts Neurergus microspilotus (Caudata: Salamandridae), which were hatched and reared in a captive breeding facility. We designed a 2 x 3 factorial experiment in which larvae were raised either at high and low temperature (15 degrees C and 18 degrees C) of conspecifics and fed either a high, medium and low level of food. The experimental results showed that growth and development rates of N. microspilotus were influenced by interaction of temperature and food levels. Larvae raised at the high food level and high temperature exhibited earlier metamorphosis and the greatest snout to vent length (SVL) compared with individuals raised at relatively low food level and low temperature. Over the experimental period, larval growth rate was highest and survival lowest at the high temperature. Our data suggest that in larvae grown at relatively low temperature, the metamorphosis time was significantly longer compared with individuals raised at relatively high temperature. At both low and high temperature, larval growth rates increased with increasing food levels, and the increase was fastest at high food level compared to medium and low food regimes. Larvae exhibited the greatest mean growth rate for SVL (0.41 mm/days) at high food level and high temperature. Information obtained from current experiment could improve the productivity of newts in captive breeding facilities to ensure the release of adequate numbers of individuals for reintroduction programs.