title: Thermoregulation of two sympatric species of horned lizards in the Chihuahuan Desert and their local extinction risk.
abstract: Thermoregulatory studies of ectothermic organisms are an important tool for ecological physiology, evolutionary ecology and behavior, and recently have become central for evaluating and predicting global climate change impacts. Here, we present a novel combination of field, laboratory, and modeling approaches to examine body temperature regulation, habitat thermal quality, and hours of thermal restriction on the activity of two sympatric, aridlands horned lizards (Phrynosoma cornutum and Phrynosoma modestum) at three contrasting Chihuahuan Desert sites in Mexico. Using these physiological data, we estimate local extinction risk under predicted climate change within their current geographical distribution. We followed the Hertz et al. (1993, Am. Nat., 142, 796-818) protocol for evaluating thermoregulation and the Sinervo et al. (2010, Science, 328, 894-899) eco-physiological model of extinction under climatic warming. Thermoregulatory indices suggest that both species thermoregulate effectively despite living in habitats of low thermal quality, although high environmental temperatures restrict the activity period of both species. Based on our measurements, if air temperature rises as predicted by climate models, the extinction model projects that P. cornutum will become locally extinct at 6% of sites by 2050 and 18% by 2080 and P. modestum will become extinct at 32% of sites by 2050 and 60% by 2080. The method we apply, using widely available or readily acquired thermal data, along with the modeling, appeared to identify several unique ecological traits that seemingly exacerbate climate sensitivity of P. modestum.
authors: Laboratorio de Herpetología, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, A. P. 70515, C.P. 04510 México, D.F., Mexico; Department of Ecology and Evolutionary Biology, Earth and Marine Sciences Building A316, University of California, Santa Cruz, CA 95064, USA. Electronic address: rafas.lara@gmail.com.
authors: Rafael A
authors: RA
authors: Lara-Reséndiz
authors: Instituto de Ecología, A. C., Miguel de Cervantes No. 120, Complejo Industrial Chihuahua, C.P. 31109 Chihuahua, Chihuahua, Mexico. Electronic address: hgadsden@gmail.com.
authors: Héctor
authors: H
authors: Gadsden
authors: School of Natural Resources and the Environment, University of Arizona, Tucson, AZ 85721, USA. Electronic address: pcrosen@email.arizona.edu.
authors: Philip C
authors: PC
authors: Rosen
authors: Department of Ecology and Evolutionary Biology, Earth and Marine Sciences Building A316, University of California, Santa Cruz, CA 95064, USA. Electronic address: lizardrps@gmail.com.
authors: Barry
authors: B
authors: Sinervo
authors: Laboratorio de Herpetología, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, A. P. 70515, C.P. 04510 México, D.F., Mexico. Electronic address: faustor@ib.unam.mx.
authors: Fausto R
authors: FR
authors: Méndez-De la Cruz
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D003889:Desert Climate; D053476:Extinction, Biological; D005260:Female; D008116:Lizards / Q000502:physiology*; D008297:Male; D008800:Mexico; D008962:Models, Theoretical; D012306:Risk; D061350:Sympatry
keywords: Climate change; Ecophysiological model; Habitat thermal quality; Phrynosoma; Thermal hours of restriction; Thermoregulatory efficiency