The precision and the extent of behavioral thermoregulation are likely to provide fitness benefits to ectotherms.Yet the factors driving variation in selected or preferred body temperature(T_(set))and its usefulness a...The precision and the extent of behavioral thermoregulation are likely to provide fitness benefits to ectotherms.Yet the factors driving variation in selected or preferred body temperature(T_(set))and its usefulness as a proxy for optimal physiological temperature(Topt)are still debated.Although T_(set)is often conserved among closely related species,substantial variation at the individual,population and species level has also been reported.However,the repeatability(calculated as the intra-class correlation coefficient)of T_(set)is generally low.One factor that influences T_(set)is feeding status,with fed reptiles typically showing higher T_(set),a process thought to aid meal digestion.Here,using experiments simulating realistic feeding and fasting regimes in Agama atra,a heliothermic lizard from southern Africa,we test if T_(set)and its repeatability under these 2 states significantly differ.Daily T_(set)ranged from 33.7 to 38.4℃,with a mean(±SE)of 36.7±0.1℃ for fed and 36.6±0.1℃ for unfed individuals.Comparisons of repeatability showed that females tend to be more consistent in the selection of body temperature than males,but not significantly so regardless of feeding status.We report some of the highest repeatability estimates of T_(set)to date(full range:0.229–0.642),and that the weak positive effects of feeding status on T_(set)did not increase its repeatability.In conclusion,one of the major prerequisites for natural selection,consistent among-individual variation,is present,making the adaptive significance of T_(set)considerably more plausible.展开更多
基金The research was conducted with the approval of the Animal Ethics Committee of Stellenbosch University(SU-ACUD14-00110)the Cape Nature permit 0056-AAA007-00206Funding was provided by an NRF Competitive Programme for Rated Researchers’grant to SCT.
文摘The precision and the extent of behavioral thermoregulation are likely to provide fitness benefits to ectotherms.Yet the factors driving variation in selected or preferred body temperature(T_(set))and its usefulness as a proxy for optimal physiological temperature(Topt)are still debated.Although T_(set)is often conserved among closely related species,substantial variation at the individual,population and species level has also been reported.However,the repeatability(calculated as the intra-class correlation coefficient)of T_(set)is generally low.One factor that influences T_(set)is feeding status,with fed reptiles typically showing higher T_(set),a process thought to aid meal digestion.Here,using experiments simulating realistic feeding and fasting regimes in Agama atra,a heliothermic lizard from southern Africa,we test if T_(set)and its repeatability under these 2 states significantly differ.Daily T_(set)ranged from 33.7 to 38.4℃,with a mean(±SE)of 36.7±0.1℃ for fed and 36.6±0.1℃ for unfed individuals.Comparisons of repeatability showed that females tend to be more consistent in the selection of body temperature than males,but not significantly so regardless of feeding status.We report some of the highest repeatability estimates of T_(set)to date(full range:0.229–0.642),and that the weak positive effects of feeding status on T_(set)did not increase its repeatability.In conclusion,one of the major prerequisites for natural selection,consistent among-individual variation,is present,making the adaptive significance of T_(set)considerably more plausible.
