The late Holocene Ambystoma fossils from Lamar Cave provide a unique opportunity to examine the important ecological and evolutionary implications of changes in life history characteristics in response to climatic change. We present a record of change in a population of tiger salamanders over the last 3000 years. Significant perturbation in the environment is possible under future climate change scenarios, and the role of local populations in the terrestrial or aquatic system may be altered. Warmer and drier climate scenarios as predicted for the Yellowstone region  would likely create less permanent aquatic environments and select for populations with primarily metamorphosing individuals, against the retention of paedomorphosis. This scenario would decrease the vertebrate biomass in the aquatic system as well as reduce the predatory pressure on aquatic Ambystoma food sources. Such changes to the ecological system could result in unexpected biological feedbacks. Also, higher percentages and rates of metamorphosis would increase gene flow between populations. This, combined with probable decreases in sizes of populations, has the potential to alter the overall genetic diversity in the meta-population over time, perhaps reducing the ability of the species to respond to further perturbation of the system.