Synergistic limits to the altitudinal distribution of a high-altitude lizard, takydromus hsuehshanensis

The geographic distribution of species can be affected by environmental factors. The adult highaltitude lizard Takydromus hsuehshanensis (altitude > 1800 m) has been shown to tolerate summer lowland air temperature; its absence in lowland areas may therefore be caused by other factors. We employed a transplant experiment to monitor survival in different life stages and female reproduction in lowland areas. We maintained the T. hsuehshanensis adults in semi-natural outdoor enclosures with sufficient food, water, and the exclusion of potential predators. The results showed that (1) the survival rates of adults gradually decreased to 23.4% from one summer to the next, (2) illness occurred in adults during the winter, and (3) reproductive capacity (2 eggs/female), hatching success (31.7%), and hatchling survival rate (0% at the end of 11 weeks) were very low during the active season. We suggest that environmental factors synergistically caused these impairments in T. hsuehshanensis across different life stages and different seasons. This may partially explain its current altitudinal distribution.