Rising global temperatures have a wide range of effects at organismal,population,and ecosystem levels.Increased winter temperatures are expected to alter the energetics of species that are dormant during this time.Hat...Rising global temperatures have a wide range of effects at organismal,population,and ecosystem levels.Increased winter temperatures are expected to alter the energetics of species that are dormant during this time.Hatchling painted turtles(Chrysemys picta)spend their first∼8 months in shallow nests on land,where they putatively rely on residual yolk reserves to fuel energetic demands during this period of inactivity before they emerge in the spring.We performed a laboratory experiment to characterize changes in residual yolk quantity in hatchling C.picta and experimentally tested the effect of temperature on residual yolk,hatchling size,and survival over the winter brumation period.We manipulated winter nest temperature by simulating two natural thermal regimes(“low”vs“high”treatments)and one regime that approximates warmer temperatures expected by 2100(“future”treatment).Because high temperature increases metabolism,we predicted that the future temperature treatment would decrease the amount of residual yolk remaining by the end of winter and reduce hatchling mass and survival.Residual yolk over winter did not differ from that before winter,and the temperature had no effect on the quantity of residual yolk or hatchling survival by the following spring.However,hatchlings that experienced future temperatures lost more mass over winter than those from the other treatments.These results correspond with previous work indicating that residual yolk does not fuel the energetic needs of hatchlings during winter.The effect of future warming temperatures on body mass may have negative consequences during energetically demanding activities during spring emergence and dispersal.展开更多
In winter,many reptiles have a period of inactivity(“brumation”).During brumation there is no energetic intake,therefore there would be an advantage to reducing energetic expenditure.The size of energetically costly...In winter,many reptiles have a period of inactivity(“brumation”).During brumation there is no energetic intake,therefore there would be an advantage to reducing energetic expenditure.The size of energetically costly organs,a major determinant of metabolic rate,is known to be flexible in many tetrapods.Seasonal plasticity of organ size could serve as both an energy-saving mechanism and a source of nutrients for brumating reptiles.We studied a population of an invasive gecko,Tarentola annularis,to test for seasonal changes in activity,metabolic rate,and mass of various organs.The observed period of inactivity was December-February.Standard metabolic rates during the activity season were 1.85 times higher than in brumating individuals.This may be attributed to decreased organ mass during winter:heart mass decreased by 37%,stomach mass by 25%,and liver mass by 69%.Interestingly,testes mass increased by 100%during winter,likely in preparation for the breeding season,suggesting that males prioritize breeding over other functions upon return to activity.The size of the kidneys and lungs remained constant.Organ atrophy occurred only after geckos reduced their activity,so we hypothesize that organ mass changes in response to(rather than in anticipation of)cold winter temperatures and the associated fasting.Degradation of visceral organs can maintain energy demands in times of low supply,and catabolism of the protein from these organs can serve as a source of both energy and water during brumation.These findings bring us closer to a mechanistic understanding of reptiles’physiological adaptations to environmental changes.展开更多
基金the field site was provided by the US Army Corps of Engineers,Illinois Department of Natural Resources(permit#NH10.0073)the US Fish andWildlife Service(permit#32576-0A022)+1 种基金approved by the Iowa State University IACUC(protocol#12-03-5570-J)supported by NSF grant LTREB DEB-0640932 to F.J.Janzen.
文摘Rising global temperatures have a wide range of effects at organismal,population,and ecosystem levels.Increased winter temperatures are expected to alter the energetics of species that are dormant during this time.Hatchling painted turtles(Chrysemys picta)spend their first∼8 months in shallow nests on land,where they putatively rely on residual yolk reserves to fuel energetic demands during this period of inactivity before they emerge in the spring.We performed a laboratory experiment to characterize changes in residual yolk quantity in hatchling C.picta and experimentally tested the effect of temperature on residual yolk,hatchling size,and survival over the winter brumation period.We manipulated winter nest temperature by simulating two natural thermal regimes(“low”vs“high”treatments)and one regime that approximates warmer temperatures expected by 2100(“future”treatment).Because high temperature increases metabolism,we predicted that the future temperature treatment would decrease the amount of residual yolk remaining by the end of winter and reduce hatchling mass and survival.Residual yolk over winter did not differ from that before winter,and the temperature had no effect on the quantity of residual yolk or hatchling survival by the following spring.However,hatchlings that experienced future temperatures lost more mass over winter than those from the other treatments.These results correspond with previous work indicating that residual yolk does not fuel the energetic needs of hatchlings during winter.The effect of future warming temperatures on body mass may have negative consequences during energetically demanding activities during spring emergence and dispersal.
基金Shahar Dubiner was supported by the Azrieli Graduate Studies Fellowship.
文摘In winter,many reptiles have a period of inactivity(“brumation”).During brumation there is no energetic intake,therefore there would be an advantage to reducing energetic expenditure.The size of energetically costly organs,a major determinant of metabolic rate,is known to be flexible in many tetrapods.Seasonal plasticity of organ size could serve as both an energy-saving mechanism and a source of nutrients for brumating reptiles.We studied a population of an invasive gecko,Tarentola annularis,to test for seasonal changes in activity,metabolic rate,and mass of various organs.The observed period of inactivity was December-February.Standard metabolic rates during the activity season were 1.85 times higher than in brumating individuals.This may be attributed to decreased organ mass during winter:heart mass decreased by 37%,stomach mass by 25%,and liver mass by 69%.Interestingly,testes mass increased by 100%during winter,likely in preparation for the breeding season,suggesting that males prioritize breeding over other functions upon return to activity.The size of the kidneys and lungs remained constant.Organ atrophy occurred only after geckos reduced their activity,so we hypothesize that organ mass changes in response to(rather than in anticipation of)cold winter temperatures and the associated fasting.Degradation of visceral organs can maintain energy demands in times of low supply,and catabolism of the protein from these organs can serve as a source of both energy and water during brumation.These findings bring us closer to a mechanistic understanding of reptiles’physiological adaptations to environmental changes.
