Brazilian tegus (Tupinambis merianae) were instrumented with telemetry encoder implants that measured and broadcast heart rate (HR), breathing rate (fR), and deep body temperature (Tb) and were then allowed to freely roam in outdoor enclosures mimicking their natural environment for a full year (2004) in order to monitor the circadian and circannual patterns in behaviour and cardio-respiratory physiology. The year was divided up into 5 seasons based upon the physiology and behaviour of the tegus: early activity season (Sept.-Nov.), late activity season (Dec.-Feb.), entrance into hibernation (March-April), hibernation (May-July), and arousal from hibernation (August). The activity seasons were characterized by warm weather with frequent rainfall which slowly decreased in temperature and precipitation as tegus started entering hibernation so that the end of the dormant season was marked by dry, cold weather. Tegus in the early activity season demonstrated high activity associated with breeding demands, displayed elevated HR and fR, and were able to maintain a large temperature differential (4-7°C) between deep body temperature (Tb) and their respective burrow (Tburrow) during sleep. As the season progressed into late activity season, average Tb remained constant but average HR and fR progressively declined indicating nightly torpor. Periods of inactivity during the active seasons were rare and associated with inclement weather. Tegus entered hibernation through bouts of inactivity that progressively increased in frequency and duration. During this time, Tb was regulated but declined at different rates in regards to daytime and nighttime values. Heart rate through the entrance into hibernation and hibernation periods frequently demonstrated arrhythmias that increased in duration but decreased with frequency as hibernation progressed. Through hibernation, Tb continued to decline for the first month but HR and fR were constant, demonstrating a temperature independent suppression of metabolism. Through the hibernation season tegus sporadically aroused and emerged from their burrows to warm up and after a short basking period would return to the burrows and swiftly resume hibernation. While hibernating, heart rate was characteristically regular but breathing was sporadic orepisodic. Arousals became more frequent towards the end of hibernation so that when they entered arousal from hibernation season most tegus were emerging daily. At this time daily maximum deep body temperature (Tbmax) swiftly returned to active season values but nighttime daily minimum deep body temperature (Tbmirt) values only showed a gradual increase through August, indicating different body temperature set points (Tbset) for active and sleep states. Changes in heart rate and breathing rate during the year showed greatest correlation with changes in photoperiod, although throughout hibernation HR and fR also showed tight correlation with Tb.

Brazilian tegus (Tupinambis merianae) were instrumented with telemetry encoder implants that measured and broadcast heart rate (HR), breathing rate (fR), and deep body temperature (Tb) and were then allowed to freely roam in outdoor enclosures mimicking their natural environment for a full year (2004) in order to monitor the circadian and circannual patterns in behaviour and cardio-respiratory physiology. The year was divided up into 5 seasons based upon the physiology and behaviour of the tegus: early activity season (Sept.-Nov.), late activity season (Dec.-Feb.), entrance into hibernation (March-April), hibernation (May-July), and arousal from hibernation (August). The activity seasons were characterized by warm weather with frequent rainfall which slowly decreased in temperature and precipitation as tegus started entering hibernation so that the end of the dormant season was marked by dry, cold weather. Tegus in the early activity season demonstrated high activity associated with breeding demands, displayed elevated HR and fR, and were able to maintain a large temperature differential (4-7°C) between deep body temperature (Tb) and their respective burrow (Tburrow) during sleep. As the season progressed into late activity season, average Tb remained constant but average HR and fR progressively declined indicating nightly torpor. Periods of inactivity during the active seasons were rare and associated with inclement weather. Tegus entered hibernation through bouts of inactivity that progressively increased in frequency and duration. During this time, Tb was regulated but declined at different rates in regards to daytime and nighttime values. Heart rate through the entrance into hibernation and hibernation periods frequently demonstrated arrhythmias that increased in duration but decreased with frequency as hibernation progressed. Through hibernation, Tb continued to decline for the first month but HR and fR were constant, demonstrating a temperature independent suppression of metabolism. Through the hibernation season tegus sporadically aroused and emerged from their burrows to warm up and after a short basking period would return to the burrows and swiftly resume hibernation. While hibernating, heart rate was characteristically regular but breathing was sporadic orepisodic. Arousals became more frequent towards the end of hibernation so that when they entered arousal from hibernation season most tegus were emerging daily. At this time daily maximum deep body temperature (Tbmax) swiftly returned to active season values but nighttime daily minimum deep body temperature (Tbmirt) values only showed a gradual increase through August, indicating different body temperature set points (Tbset) for active and sleep states. Changes in heart rate and breathing rate during the year showed greatest correlation with changes in photoperiod, although throughout hibernation HR and fR also showed tight correlation with Tb.

Brazilian tegus (Tupinambis merianae) were instrumented with telemetry encoder implants that measured and broadcast heart rate (HR), breathing rate (fR), and deep body temperature (Tb) and were then allowed to freely roam in outdoor enclosures mimicking their natural environment for a full year (2004) in order to monitor the circadian and circannual patterns in behaviour and cardio-respiratory physiology. The year was divided up into 5 seasons based upon the physiology and behaviour of the tegus: early activity season (Sept.-Nov.), late activity season (Dec.-Feb.), entrance into hibernation (March-April), hibernation (May-July), and arousal from hibernation (August). The activity seasons were characterized by warm weather with frequent rainfall which slowly decreased in temperature and precipitation as tegus started entering hibernation so that the end of the dormant season was marked by dry, cold weather. Tegus in the early activity season demonstrated high activity associated with breeding demands, displayed elevated HR and fR, and were able to maintain a large temperature differential (4-7°C) between deep body temperature (Tb) and their respective burrow (Tburrow) during sleep. As the season progressed into late activity season, average Tb remained constant but average HR and fR progressively declined indicating nightly torpor. Periods of inactivity during the active seasons were rare and associated with inclement weather. Tegus entered hibernation through bouts of inactivity that progressively increased in frequency and duration. During this time, Tb was regulated but declined at different rates in regards to daytime and nighttime values. Heart rate through the entrance into hibernation and hibernation periods frequently demonstrated arrhythmias that increased in duration but decreased with frequency as hibernation progressed. Through hibernation, Tb continued to decline for the first month but HR and fR were constant, demonstrating a temperature independent suppression of metabolism. Through the hibernation season tegus sporadically aroused and emerged from their burrows to warm up and after a short basking period would return to the burrows and swiftly resume hibernation. While hibernating, heart rate was characteristically regular but breathing was sporadic orepisodic. Arousals became more frequent towards the end of hibernation so that when they entered arousal from hibernation season most tegus were emerging daily. At this time daily maximum deep body temperature (Tbmax) swiftly returned to active season values but nighttime daily minimum deep body temperature (Tbmirt) values only showed a gradual increase through August, indicating different body temperature set points (Tbset) for active and sleep states. Changes in heart rate and breathing rate during the year showed greatest correlation with changes in photoperiod, although throughout hibernation HR and fR also showed tight correlation with Tb. / Science, Faculty of / Zoology, Department of / Graduate

<p>Seasonal heterothermy—an orchestrated set of extreme physiological responses—is directly responsible for the over-winter survival of many mammalian groups living in seasonal environments. Historically, it was thought that the use of seasonal heterothermy (i.e. daily torpor and hibernation) was restricted to cold-adapted species; it is now known that such thermoregulatory strategies are used by more species than previously appreciated, including many tropical species. The dwarf and mouse lemurs (family Cheirogaleidae) are among the few primates known to use seasonal heterothermy to avoid Madagascar’s harsh and unpredictable environments. These primates provide an ideal study system for investigating a common mechanism of mammalian seasonal heterothermy. The overarching theme of this dissertation is to understand both the intrinsic and extrinsic drivers of heterothermy in three species of the family Cheirogaleidae. By using transcriptome sequencing to characterize gene expression in both captive and natural settings, we identify unique patterns of differential gene expression that are correlated with extreme changes in physiology in two species of dwarf lemurs: C. medius under captive conditions at the Duke Lemur Center and C. crossleyi studied under field conditions in Madagascar. Genes that are differentially expressed appear to be critical for maintaining the health of these animals when they undergo prolonged periods of metabolic depression concurrent with the hibernation phenotype. Further, a comparative analysis of previously studied mammalian heterotherms identifies shared genetic mechanisms underlying the hibernation phenotype across the phylogeny of mammals. Lastly, conducting a diet manipulation study with a captive colony of mouse lemurs (Microcebus murinus) at the Duke Lemur Center, we investigated the degree to which dietary effects influence torpor patterns. We find that tropical primate heterotherms may be exempt from the traditional paradigms governing cold-adapted heterothermy, having evolved different dietary strategies to tolerate circadian changes in body temperature.</p> / Dissertation

Pronounced seasonal adaptations in physiology and behaviour are exhibited by mammals living in polar and temperate habitats. These include the development of a winter coat, altered fat reserves, reproductive quiescence and food hoarding. Maintaining constant body temperature (Tb) during winter is energetically very costly, and so many small mammals periodically abandon homeothermy in favour of heterothermy. The two principal heterothermic strategies are daily torpor and seasonal hibernation, in which bouts of profound hypothermia range from a few hours to several days (respectively). It is now clear that hypothalamic thyroid hormone (TH) regulation, and specifically the availability of the active metabolite triiodothyronine (T3), is a critical regulator of seasonal reproductive cycles in many species including birds and mammals. The impact of this signal as a switch for seasonal changes in physiology has been highlighted by the demonstration that blockade of this pathway prevents seasonal adaption in hamsters. Peripheral TH signalling is also a principle regulator of metabolic rate in mammals. Despite these findings nothing is yet known about the involvement of central (hypothalamic) and peripheral TH cycles in the expression of torpor and hibernation. Within this thesis, the role of TH dynamics both in the brain and peripheral circulation is examined within three models of heterothermia: the Siberian (Phodopus sungorus) and European (Cricetus cricetus) hamsters, which employ daily torpor and hibernation, respectively, and the laboratory mouse (Mus Musculus) which exhibits torpor in response to metabolic stress such as food restriction. To delineate TH regulation and signalling in the context of both seasonal and acute physiological responses, the expression of genes involved in thyroid hormones conversion (e.g. Deiodinase type II (Dio2) and type III (Dio3) and transport (e.g. Monocarboxylate transporter 8, Mct8) within the ependymal layer of the ventral 3rd ventricle have been detailed across seasonal (long (LD) and short day (SD)) photoperiods, and during normothermic and hypothermic conditions. Furthermore, TH concentrations have been directly measured within the hypothalami of P. sungorus and C. cricetus, and TH responsive genes (e.g. Hairless (Hr) and Thyrotropin releasing hormone (TRH) to determine the potential impact of regional T3 signalling. As expected, Dio2 and Dio3 expression in P. sungorus exhibited a strong seasonal cycle indicative of elevated T3 production during SD (reduced Dio2 and elevated Dio3). Unexpectedly, total T3 measures from hypothalamic extracts revealed no significant alteration either seasonally or during torpor/hibernation in hamsters. However, Hr expression in the ependymal layer and TRH expression in the paraventricular nucleus (PVN) suggests low T3 concentrations during SD are localised to specific regions and does not encompass the whole hypothalamus per se. In addition, altered serum TH concentrations implicate seasonal and torpor associated dynamics that may play a role in seasonal adaptation and hypothermia. Finally, data from transgenic mice strongly implicate the melatonin-related receptor (GPR50) in leptin signalling and aberrant thermogenesis in mice.

No description available.

Bat populations in the eastern United States are currently declining at unprecedented rates as a result of habitat loss, commercial wind energy development, and white-nose syndrome. Effective conservation of these declining populations requires knowledge of several aspects of summer and winter ecology, including daytime habitat use (day-roost selection and social behaviors), nocturnal habitat use (foraging habitat selection, prey selection, and prey abundance), and winter hibernation (torpor) patterns. This dissertation addresses these questions for Rafinesque’s big-eared bat (Corynorhinus rafinesquii), a species of conservation concern in the southeastern United States. Kentucky represents the northern edge of the range of Rafinesque’s big-eared bat, and summer and winter behaviors in Kentucky are likely to differ from what has been observed in southern portion of the range, where available habitats and climate are different. My research occurred in two study areas in Kentucky, Mammoth Cave National Park in central Kentucky, and the Ballard Wildlife Management areas in western Kentucky. This dissertation includes all of the work done in western Kentucky, where I radio-tagged 48 adult big-eared bats and documented daytime and nighttime habitat use. Also included is a portion of the work done in central Kentucky, focusing on hibernation patterns of 14 adult big-eared bats radio-tagged during the winter at Mammoth Cave. Data disseminated in this dissertation provide insights into the summer and winter ecology of Rafinesque’s big-eared bat in Kentucky, and can be used to manage populations threatened by habitat loss and white-nose syndrome.

Despite an IUCN conservation status of critically endangered, Juliana’s golden mole (Neamblysomus julianae) has received no ecological research attention to date. The species urgently requires conservation attention, but a poor understanding its biology, ecology and distribution makes effective conservation planning almost impossible. In light of this, a thorough understanding of the habitat requirements for this habitat specific species was needed. Additionally, the cryptic lifestyle of Juliana’s golden mole has resulted in very few distribution records for the species. Little was known about the animals’ daily and seasonal activity patterns or movement patterns. This study revealed that Juliana’s golden mole is range restricted on account of sandy soils that have a uniform particle size distribution. This feature limits substrate compaction, making tunnelling far easier for these small mammals. In comparison to uninhabited areas, occupied habitat had greater vegetation cover provided by trees and shrubs, and this would be expected to provide a cooler and moister microenvironment. The ecological parameters associated with the species presence were then used, in addition to existing GIS data, to predict regions of potentially suitable habitat. This process revealed large potentially inhabitable areas in the northern parts of South Africa. Preliminary ground-truthing has shown the model to be relatively accurate with three potentially new populations having been identified. Contrary to what has been reported in the literature, Juliana’s golden mole does not appear to be strictly nocturnal. Instead, an adaptive pattern of activity was observed, governed by soil temperature. Body temperature was found to fluctuate to some degree with that of the soil temperature, but fluctuations were regulated by behavioural thermoregulation. Seasonal activity is highly correlated with rainfall. Rain moistens the soil making it significantly softer and far easier to tunnel through. Using this and other information acquired through the course of the study, the thesis culminates with an evaluation of conservation concerns and proposed conservation management actions. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Zoology and Entomology / unrestricted

Fifty-nine female and six male little brown myotis (Myotis lucifugus) were radio-tagged during the summers of 2012, 2013, 2014, and 2015 in Yellowstone National Park. The grand models for daily maximum skin temperature (F98,154 = 1.55, P = 0.007), daily minimum skin temperature (F98,154 = 1.33, P = 0.05), and daily variation in skin temperature (F98,154 = 1.56, P = 0.006) were significant across roost type and reproductive condition class for adult females. Roosts were classified into Types A (warmest roosts), B (roosts with largest daily temperature variance), and C (stable and cool roosts) depending on differences in mean maximum, minimum, and variance in temperatures per day (P < 0.001). A total of 347 torpor bouts were recorded from 38 females across the 2012 to 2015 summer seasons. Bats across different reproductive classes and roost types used torpor at different hours of the day. My research suggests that adult female little brown myotis at high elevations in the Park extensively use and rely on building structures for roosting sites during the reproductive season, whereas males used primarily natural roosts.

The pichi Zaedyus pichiy (Xenarthra, Dasypodidae) is a poorly known, diurnal armadillo inhabiting arid and semi-arid regions of Argentina and Chile that has endured substantial population declines. My objective was to elucidate different aspects of the natural history of Z. pichiy as a first step towards establishing a conservation plan. Wild and captive pichis were studied. Body temperature of wild pichis averaged 35.2±1.2 °C and was highly variable (range 32.2 – 38.3 °C). Temperature measurements of semi-captive males showed that pichis can survive energetically challenging periods by entering hibernation or daily torpor. Stomach contents of poached animals revealed that pichis feed predominantly on insects but also ingest plant material, vertebrates and arachnids. This opportunistic, omnivorous feeding strategy allows them to thrive where food type and availability vary seasonally. The reproductive cycle of pichis was studied by means of histological and fecal hormone analyses. Pichis are seasonal breeders that produce one yearly litter of 1 to 2 offspring, and the initiator of breeding season seems to be an increase in daylength. The absence of regular estrous cycles and corpora lutea in non-pregnant females, and immediate mating attempts after pairing, all suggest that pichis are induced ovulators. Clinical examinations and hematological, serological and coproparasitological analyses of free-ranging pichis, and necropsies and histological examinations of confiscated pichis and roadkills, indicate that the populations are currently in good health. While parasites were often found, no severe pathologies were observed. Infections with potentially zoonotic diseases were rare: only a few pichis were seropositive for Trypanosoma cruzi, none had antibodies against Toxoplasma gondii, and none of the histologically examined individuals presented lesions attributable to these pathogens. Elevated ambient humidity levels often caused moist dermatitis with epidermal detachment in captive pichis. Poaching is currently considered to have a much higher negative impact on the wild populations than disease epidemics. Mortality due to heavy poaching activity may be difficult, if not impossible, to compensate by the current birth rates. This preliminary database on the natural history and reproduction of pichis will assist efforts to conserve this little-known species of armadillo.