The diversity of rodents in Asian deserts is high.Nevertheless,little is known about their use of daily torpor and hibernation,which are employed by many small mammals worldwide for energy and water conservation to pe...The diversity of rodents in Asian deserts is high.Nevertheless,little is known about their use of daily torpor and hibernation,which are employed by many small mammals worldwide for energy and water conservation to permit survival under adverse environmental conditions.We quantified for the first time,using temperature transponders and data loggers,long-term torpor expression and patterns in sympatric desert hamsters Phodopus roborovskii,striped hamsters Cricetulus barabensis and 3-toed jerboas Dipus sagitta under controlled conditions.Animals were live-trapped in Inner Mongolia in August and held in captivity under short photoperiods and low ambient temperatures(T,s)for about 6 months.Both hamster species(~half of individuals)expressed spontaneous(food available)daily torpor.Daily torpor in desert hamsters was less frequent and shallower than that in striped hamsters,which also had longer torpor bouts during torpor at T 15.8±0.4℃.Only one individual jerboa entered hibernation spontaneously at T,6.2±0.5℃,but all hibernated after food deprivation.The 2 hamster species only slightly changed their body mass during the acclimation,whereas jerboas greatly increased their body mass by 27.9%during the first 2 months of acclimation probably as a preparation for the hibernating season.Our data show that short photoperiod and moderately low T,induces spontaneous daily torpor in the 2 hamster species,suggesting that it is used regularly in the wild.Hibernation in Jerboas occurred at T,6.2±0.5°C especially when food was withheld suggesting limited food availability is the proximate trigger of their hibernation.展开更多
Energy conservation is paramount for small mammals because of their small size,large surface area to volume ratio,and the resultant high heat loss to the environment.To survive on limited food resources and to fuel th...Energy conservation is paramount for small mammals because of their small size,large surface area to volume ratio,and the resultant high heat loss to the environment.To survive on limited food resources and to fuel their expensive metabolism during activity,many small mammals employ daily torpor to reduce energy expenditure during the rest phase.We hypothesized that a small terrestrial semelparous marsupial,the brown antechinus Antechinus stuartii,would maximize activity when foraging conditions were favorable to gain fat reserves before their intense breeding period,but would increase torpor use when conditions were poor to conserve these fat reserves.Female antechinus were trapped and implanted with small temperature-sensitive radio transmitters to record body temperature and to quantify torpor expression and activity patterns in the wild.Most antechinus used torpor at least once per day over the entire study period.Total daily torpor use increased and mean daily body temperature decreased significantly with a reduction in minimum ambient temperature.Interestingly,antechinus employed less torpor on days with more rain and decreasing barometric pressure.In contrast to torpor expression,activity was directly related to ambient temperature and inversely related to barometric pressure.Our results reveal that antechinus use a flexible combination of physiology and behavior that can be adjusted to manage their energy budget according to weather variables.展开更多
基金supported by grants from the National Natural Science Foundation of China to QSC(31470473 and 32260261)a Chinese Academy of Sciences Visiting Scientists Fellowship to FG.
文摘The diversity of rodents in Asian deserts is high.Nevertheless,little is known about their use of daily torpor and hibernation,which are employed by many small mammals worldwide for energy and water conservation to permit survival under adverse environmental conditions.We quantified for the first time,using temperature transponders and data loggers,long-term torpor expression and patterns in sympatric desert hamsters Phodopus roborovskii,striped hamsters Cricetulus barabensis and 3-toed jerboas Dipus sagitta under controlled conditions.Animals were live-trapped in Inner Mongolia in August and held in captivity under short photoperiods and low ambient temperatures(T,s)for about 6 months.Both hamster species(~half of individuals)expressed spontaneous(food available)daily torpor.Daily torpor in desert hamsters was less frequent and shallower than that in striped hamsters,which also had longer torpor bouts during torpor at T 15.8±0.4℃.Only one individual jerboa entered hibernation spontaneously at T,6.2±0.5℃,but all hibernated after food deprivation.The 2 hamster species only slightly changed their body mass during the acclimation,whereas jerboas greatly increased their body mass by 27.9%during the first 2 months of acclimation probably as a preparation for the hibernating season.Our data show that short photoperiod and moderately low T,induces spontaneous daily torpor in the 2 hamster species,suggesting that it is used regularly in the wild.Hibernation in Jerboas occurred at T,6.2±0.5°C especially when food was withheld suggesting limited food availability is the proximate trigger of their hibernation.
基金This research was supported by Honours research funds from the University of New England to T.H.,the University of New England Deputy Vice-Chancellor(Research)Award to C.S.and the Australian Research Council to F.G.
文摘Energy conservation is paramount for small mammals because of their small size,large surface area to volume ratio,and the resultant high heat loss to the environment.To survive on limited food resources and to fuel their expensive metabolism during activity,many small mammals employ daily torpor to reduce energy expenditure during the rest phase.We hypothesized that a small terrestrial semelparous marsupial,the brown antechinus Antechinus stuartii,would maximize activity when foraging conditions were favorable to gain fat reserves before their intense breeding period,but would increase torpor use when conditions were poor to conserve these fat reserves.Female antechinus were trapped and implanted with small temperature-sensitive radio transmitters to record body temperature and to quantify torpor expression and activity patterns in the wild.Most antechinus used torpor at least once per day over the entire study period.Total daily torpor use increased and mean daily body temperature decreased significantly with a reduction in minimum ambient temperature.Interestingly,antechinus employed less torpor on days with more rain and decreasing barometric pressure.In contrast to torpor expression,activity was directly related to ambient temperature and inversely related to barometric pressure.Our results reveal that antechinus use a flexible combination of physiology and behavior that can be adjusted to manage their energy budget according to weather variables.
