A comparison of the life histories and growth patterns of populations of the salamander Ambystoma gracile (Baird) from permanent low-altitude and montane lakes

Abstract

Laboratory and field studies were initiated to study the life-history patterns of populations of Ambystoma gracile from three permanent lakes located at different altitudes in southwestern British Columbia. Laboratory studies indicated clear differences between low- and high-altitude populations with respect to larval growth, timing of metamorphosis, size at metamorphosis, and the incidence of neoteny. Field studies indicated that low-altitude neotenous females became sexually mature at a length of 7.1 cm (snout to vent length, SVL); but owing to the shorter seasons within higher altitude lakes, neotenous females required more seasons to attain sexual maturity. High- and low-altitude males attained sexual maturity at 7.4-cm SVL, but a few smaller, sexually mature males were discovered within the high-altitude lake. Neotenous females reproduced annually within the low-altitude lake, but high-altitude neotenous females did not reproduce during successive years. Possible genetic adaptations to low and high altitudes are discussed.