Low cold tolerance of the invasive lizard Eutropis multifasciata constrains its potential elevation distribution in Taiwan.

Abstract

1. The invasive many-lined sun skink, Eutropis multifasciata, is established in much of southern Taiwan and is spreading northward. We investigated whether winter temperatures constrain further dispersion of this skink by comparing its cold tolerance to the spatial distribution of winter temperatures in Taiwan. 2. We measured the 28-day survival rate of this species at 4 constant temperatures (10-16°C in 2°C increments) and its critical thermal minimum (CTmin), i.e., the body temperature at which the righting reflex is lost during the cooling process. For comparison with the spatial distribution of temperatures over Taiwan, we used the biophysical model Niche Mapper™ in order to simulate the soil temperatures, where lizards are inactive in the winter, during the coldest month of the year, January, under three climatic scenarios (average temperature, average-3°C, average+3°C). 3. Our results indicate that this species has low tolerance to cold. Combining cold tolerance data with soil temperature data suggests that its upper elevation limit could range from 1000 m to 1500 m, above which the weather is lethal and precludes overwintering. The locations of sightings of E. multifasciata are consistent with this prediction, with no known locations above 500 m elevation. 4. This study highlights that the winter climate is a major factor in determining population establishment and hence in limiting this species' range. Future studies would benefit from accounting for low winter temperatures and their potential influence on range limits of invasive species.