Population biology of the unusual thermoconforming lizards of the Andes Mountains of Peru (Squamata: Gymnophthalmidae)

Abstract

AbstractMontane animals require different adaptations than lowland species because of more severe conditions. Proctoporus lizards of the Andes Mountains experience cold temperatures year‐round, which may affect their activity. Two species of this poorly known genus, P. unsaacae and P. sucullucu, have similar morphology and ecology, but had never been studied in detail. The purpose of this project was to compare the population biology of the two species and to ascertain whether they were more likely to share ecological similarities with phylogenetic relatives or with other unrelated lizards of the Andes. We established two permanent plots in the Sacred Valley of the Incas in Cusco region, Peru, and examined the thermal ecology, movement, sex ratio, longevity, population sizes, growth patterns, reproduction and other factors over a period of 4 years. Proctoporus unsaacae and P. sucullucu were similar in most aspects of their ecology except that P. sucullcu was larger, had smaller population sizes, and fewer recaptures. Both species live exclusively under rocks and are strict thermoconformers who do not actively thermoregulate their body temperatures by basking, as other high Andean lizards do. The two species have reverse sexual dimorphism with P. unsaacae having larger females and P. sucullcu having larger males. The species are highly philopatric with average movement of less than 7 m in a lifetime. Both appear to be relatively long‐lived with an individual P. unsaacae living longer than 2 years 8 months. At both sites, populations age structures had few juveniles and we detected a declining population of P. unsaacae in Urubamba. This project lays the groundwork for more in‐depth studies of the ecology of both species and their high‐elevation habitats.