Thermoregulation in two sympatric populations of lizard: Sceloporus lineolateralis and Sceloporus poinsettii (Squamata: Phrynosomatidae) in Durango, Mexico

Abstract

Environmental temperature is an important factor that regulates activity and physiological processes ofectotherms. Because sympatric species are exposed to similar thermal niche conditions, closely related species couldpresent similar thermal requirements. This similarity may generate interspecific competition for optimal thermalspace. The thermal ecology of the sympatric viviparous lizards Sceloporus lineolateralis and S. poinsettii (Sceloporustorquatus and Sceloporus poinsettii groups, respectively) were studied in natural populations in Peñón Blanco,Durango, Mexico. We found that active body temperatures and selected body temperatures were similar amongspecies. However, S. poinsettii exhibited higher efficiency and accuracy of thermoregulation because the preferredthermal range of this species was wider. Finally their thermal preferences are analogous to those previously reportedfor the both groups and the genus.