Adaptation or acclimation of thermal requirements to environmental conditions can reduce thermoregulation costs and increase fitness,especially in ectotherms,which rely heavily on environmental temperatures for thermo...Adaptation or acclimation of thermal requirements to environmental conditions can reduce thermoregulation costs and increase fitness,especially in ectotherms,which rely heavily on environmental temperatures for thermoregulation.Insight into how thermal niches have shaped thermal requirements across evolutionary history may help predict the survival of species during climate change.The lizard genus Sceloporus has a widespread distribution and inhabits an ample variety of habitats.We evaluated the effects of geographical gradients(i.e.elevation and latitude)and local environmental temperatures on thermal requirements(i.e.preferred body temperature,active body temperature in the field,and critical thermal limits)of Sceloporus species using published and field-collected data and performing phylogenetic comparative analyses.To contrast macro-and micro-evolutional patterns,we also performed intra-specific analyses when sufficient reports existed for a species.We found that preferred body temperature increased with elevation,whereas body temperature in the field decreased with elevation and increased with local environmental temperatures.Critical thermal limits were not related to the geographic gradient or environmental temperatures.The apparent lack of relation of thermal requirements to geographic gradient may increase vulnerability to extinction due to climate change.However,local and temporal variations in thermal landscape determine thermoregulation opportunities and may not be well represented by geographic gradient and mean environmental temperatures.Results showed that Sceloporus lizards are excellent thermoregulators,have wide thermal tolerance ranges,and the preferred temperature was labile.Our results suggest that Sceloporus lizards can adjust to different thermal landscapes,highlighting opportunities for continuous survival in changing thermal environments.展开更多
ndividuals that inhabit broad elevational ranges may experience unique environmental challenges.Because temperature decreases with increased elevation,the ectotherms living at high elevations have to manage limited ac...ndividuals that inhabit broad elevational ranges may experience unique environmental challenges.Because temperature decreases with increased elevation,the ectotherms living at high elevations have to manage limited activity time and high thermoregulatory effort.The resting metabolic rate(RMR)of a postabsorptive animal is related to its total energy requirements as well as many other fitness traits.Mesquite lizards(Sceloporus grammicus)living on La Malinche Volcano,Mexico,inhabit a wide elevational range with some populations apparently thriving above the tree line.We measured the RMR of lizards from different elevations(i.e.,2,600,3,200,and 4,100 m)at four ecologically relevant temperatures(i.e.,15,25,30,and 35°C)and found that RMR of mesquite lizards increased with temperature and body mass.More importantly,lizards from the high-elevation population had mass specific RMR that was higher at all temperatures.While the higher RMRs of high-elevation populations imply higher metabolic costs at a given temperature these lizards were also smaller.Both of these traits may allow these high elevation populations to thrive in the face of the thermal challenges imposed by their environment.展开更多
基金CONAHCyT for funding:a postdoctoral grant to M.P.and the Catedras CONAHCyT program to A.D.V.P.(project number:883).
文摘Adaptation or acclimation of thermal requirements to environmental conditions can reduce thermoregulation costs and increase fitness,especially in ectotherms,which rely heavily on environmental temperatures for thermoregulation.Insight into how thermal niches have shaped thermal requirements across evolutionary history may help predict the survival of species during climate change.The lizard genus Sceloporus has a widespread distribution and inhabits an ample variety of habitats.We evaluated the effects of geographical gradients(i.e.elevation and latitude)and local environmental temperatures on thermal requirements(i.e.preferred body temperature,active body temperature in the field,and critical thermal limits)of Sceloporus species using published and field-collected data and performing phylogenetic comparative analyses.To contrast macro-and micro-evolutional patterns,we also performed intra-specific analyses when sufficient reports existed for a species.We found that preferred body temperature increased with elevation,whereas body temperature in the field decreased with elevation and increased with local environmental temperatures.Critical thermal limits were not related to the geographic gradient or environmental temperatures.The apparent lack of relation of thermal requirements to geographic gradient may increase vulnerability to extinction due to climate change.However,local and temporal variations in thermal landscape determine thermoregulation opportunities and may not be well represented by geographic gradient and mean environmental temperatures.Results showed that Sceloporus lizards are excellent thermoregulators,have wide thermal tolerance ranges,and the preferred temperature was labile.Our results suggest that Sceloporus lizards can adjust to different thermal landscapes,highlighting opportunities for continuous survival in changing thermal environments.
基金from CONACyT(MP)and the Catedras CONA-CyT program(ADP,883)the Secretaría de Medio Ambiente y Recursos Naturales for providing the collecting permits(SGPA/DGVS/15396/15 and SGPA/DGVS/007736/18).
文摘ndividuals that inhabit broad elevational ranges may experience unique environmental challenges.Because temperature decreases with increased elevation,the ectotherms living at high elevations have to manage limited activity time and high thermoregulatory effort.The resting metabolic rate(RMR)of a postabsorptive animal is related to its total energy requirements as well as many other fitness traits.Mesquite lizards(Sceloporus grammicus)living on La Malinche Volcano,Mexico,inhabit a wide elevational range with some populations apparently thriving above the tree line.We measured the RMR of lizards from different elevations(i.e.,2,600,3,200,and 4,100 m)at four ecologically relevant temperatures(i.e.,15,25,30,and 35°C)and found that RMR of mesquite lizards increased with temperature and body mass.More importantly,lizards from the high-elevation population had mass specific RMR that was higher at all temperatures.While the higher RMRs of high-elevation populations imply higher metabolic costs at a given temperature these lizards were also smaller.Both of these traits may allow these high elevation populations to thrive in the face of the thermal challenges imposed by their environment.
