title: Evolutionary stasis and lability in thermal physiology in a group of tropical lizards.
abstract: Understanding how quickly physiological traits evolve is a topic of great interest, particularly in the context of how organisms can adapt in response to climate warming. Adjustment to novel thermal habitats may occur either through behavioural adjustments, physiological adaptation or both. Here, we test whether rates of evolution differ among physiological traits in the cybotoids, a clade of tropical Anolis lizards distributed in markedly different thermal environments on the Caribbean island of Hispaniola. We find that cold tolerance evolves considerably faster than heat tolerance, a difference that results because behavioural thermoregulation more effectively shields these organisms from selection on upper than lower temperature tolerances. Specifically, because lizards in very different environments behaviourally thermoregulate during the day to similar body temperatures, divergent selection on body temperature and heat tolerance is precluded, whereas night-time temperatures can only be partially buffered by behaviour, thereby exposing organisms to selection on cold tolerance. We discuss how exposure to selection on physiology influences divergence among tropical organisms and its implications for adaptive evolutionary response to climate warming.
authors.affiliation: Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, , Cambridge, MA 02138, USA, Department of Ecology, Evolution and Environmental Biology, Columbia University, , 1200 Amsterdam Avenue, NY 10027, USA, School of Geography, University of Nottingham, , Sir Clive Granger Building, University Park, Nottingham NG7 2RD, UK, Stuyvestant High School, , 345 Chambers Street, New York, NY 10282, USA, Department of Wildlife, Fish and Conservation Biology, University of California, , Davis, One Shields Avenue, Davis, CA 95616, USA, Sociedad Ornitológica de la Hispaniola, , Gustavo Mejía Ricart 119 B, Apto. 401, Galerías Residencial, Santo Domingo, Dominican Republic, Department of Biology, Indiana State University, , Terre Haute, IN 47809, USA.
authors.forename: Martha M
authors.initials: MM
authors.lastname: Muñoz
authors.forename: Maureen A
authors.initials: MA
authors.lastname: Stimola
authors.forename: Adam C
authors.initials: AC
authors.lastname: Algar
authors.forename: Asa
authors.initials: A
authors.lastname: Conover
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Rodriguez
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Landestoy
authors.forename: George S
authors.initials: GS
authors.lastname: Bakken
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Losos
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005075:Biological Evolution; D001833:Body Temperature Regulation; D057231:Climate Change; D008116:Lizards / Q000502:physiology*; D013696:Temperature; D014329:Tropical Climate; D014900:West Indies
keywords: Anolis lizards; Bogert effect; physiological evolution; thermal physiology; thermoregulation