Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/57386
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dc.contributor.authorWacker, Christineen
dc.contributor.authorGeiser, Fritzen
dc.contributor.authorKoertner, Gerharden
dc.date.accessioned2024-01-17T05:43:23Z-
dc.date.available2024-01-17T05:43:23Z-
dc.date.created2017-06-
dc.date.issued2017-10-27-
dc.identifier.urihttps://hdl.handle.net/1959.11/57386-
dc.descriptionPlease contact rune@une.edu.au if you require access to this thesis for the purpose of research or study.en
dc.description.abstract<p>Daily torpor and hibernation in adult mammals and birds have been extensively studied, but there is still much to learn about these fascinating physiological states. Because torpor in marsupials is widespread, partially because many marsupial species are small in size and heterothermy is common in small species, a growing number of studies have successfully investigated the use of heterothermy in this group. </p> <p>However, most available data on heterothermy in marsupials exist for adults, and very little for growing young, mostly due to the challenges of measuring body temperature (T<sub>b</sub>) in very small animals. There is currently much well-placed interest in the relationship between heterothermy and climate change, and how increasing air temperatures (T<sub>a</sub>s) may influence the use of heterothermy in these species. However, an animal may be most at risk of being negatively affected by increasing or variable T<sub>a</sub>s when it is still developing, especially in the case of marsupials which have potentially vulnerable altricial young. While some studies have investigated the development of thermoregulation in these tiny animals, continuous temperature measurements, that do not disturb the animal, have not been obtained due to the lack of appropriate technology. </p> <p>The species chosen for my study were fat-tailed dunnarts (<i>Sminthopsis crassicaudata</i>) and stripefaced dunnarts (<i>S. macroura</i>), which are small marsupials from the family Dasyuridae (carnivorous marsupials). These two species are common in the wild and are ideal for laboratory work as they are easy to maintain and breed in captivity. The central theme of my study was the development of thermoregulation and torpor in very small, developing dunnarts. My first aim was to find a method of taking continuous measurements of T<sub>b</sub> in very small animals that would not interrupt torpor use, as conventional transmitters are too large to be used in such small animals. By testing and confirming the reliability and accuracy of small temperature-sensitive transponders, I was able to use these to obtain continuous T<sub>b</sub> readings in animals only 60 days (d) old, at approximately 8 g, and still in the nest.</p> <p>The second aim of my study was to measure the development of endothermy and torpor use in the fat-tailed dunnart (<i>S. crassicaudata</i>). When animals were placed at T<sub>a</sub> of 18 °C at 40 d they were poikilothermic, rapidly cooling to T<sub>a</sub>, at 48 d animals cooled more slowly and could maintain T<sub>b</sub> at approximately 25 °C, and at 56 d animals were endothermic, maintaining a high, normothermic T<sub>b</sub> at the low T<sub>a</sub>. Animals at ~60 d entered an apparent state of torpor, but being unable to rewarm, became hypothermic. However, these animals could rewarm when given access to radiant heat. Basking in this instance was not an optional method of reducing the cost of rewarming, but was instead necessary to rewarm and avoid hypothermia, and therefore essential to be able to use torpor. The incidence of hypothermia decreased until ~120 d when all animals could actively rewarm, without the aid of radiant heat. This is the first time, to my knowledge, that torpor use in an animal that is not yet fully endothermic has been observed, and indicates that the development of thermoregulation in this, and likely other species occurs in three stages: poikilothermy, partial endothermy and heterothermic endothermy. This discovery may also have some evolutionary implications that need to be considered, as heterothermy was possibly an intermediate stage between poikilothermy and homeothermy in the evolution of endothermy in mammals. The observation of basking in juveniles could reveal the step that explains how pre-endothermic animals were able to move beyond the heterothermic stage in the evolution of endothermy.</p>en
dc.languageenen
dc.titleThermal Energetics of Dunnarts (Marsupialia) in Relation to Development, Insulation, Torpor Expression and Baskingen
dc.typeThesis Doctoralen
dc.subject.keywordsZoologyen
dc.subject.keywordsConservation and Biodiversityen
dc.subject.keywordsAnimal Physiology - Systemsen
local.contributor.firstnameChristineen
local.contributor.firstnameFritzen
local.contributor.firstnameGerharden
local.subject.for2008060899 Zoology not elsewhere classifieden
local.subject.for2008060603 Animal Physiology - Systemsen
local.subject.for2008050202 Conservation and Biodiversityen
local.subject.seo2008970106 Expanding Knowledge in the Biological Sciencesen
local.subject.seo2008960699 Environmental and Natural Resource Evaluation not elsewhere classifieden
local.subject.seo2008960811 Sparseland, Permanent Grassland and Arid Zone Flora, Fauna and Biodiversityen
dc.date.conferred2017en
local.hos.emailers-sabl@une.edu.auen
local.thesis.passedPasseden
local.thesis.degreelevelDoctoralen
local.thesis.degreenameDoctor of Philosophy - PhDen
local.contributor.grantorUniversity of New Englanden
local.profile.schoolSchool of Environmental and Rural Scienceen
local.profile.schoolSchool of Environmental and Rural Scienceen
local.profile.schoolSchool of Environmental and Rural Scienceen
local.profile.emailcwacker2@une.edu.auen
local.profile.emailfgeiser@une.edu.auen
local.profile.emailgkoertne@une.edu.auen
local.output.categoryT2en
local.record.placeauen
local.record.institutionUniversity of New Englanden
local.identifier.epublicationsrecordune_thesis-20170620-130149en
local.contributor.lastnameWackeren
local.contributor.lastnameGeiseren
local.contributor.lastnameKoertneren
dc.identifier.staffune-id:cwacker2en
dc.identifier.staffune-id:fgeiseren
dc.identifier.staffune-id:gkoertneen
local.profile.orcid0000-0001-7621-5049en
local.profile.orcid0000-0001-8230-0709en
local.profile.roleauthoren
local.profile.rolesupervisoren
local.profile.rolesupervisoren
local.identifier.unepublicationidune:_thesis-20170620-130149en
local.identifier.unepublicationidune:_thesis-20170620-130149en
local.RightsStatementCopyright 2017 - Christine Wackeren
dc.identifier.academiclevelAcademicen
dc.identifier.academiclevelAcademicen
dc.identifier.academiclevelAcademicen
local.thesis.bypublicationNoen
local.title.maintitleThermal Energetics of Dunnarts (Marsupialia) in Relation to Development, Insulation, Torpor Expression and Baskingen
local.output.categorydescriptionT2 Thesis - Doctorate by Researchen
local.relation.doi10.1007/s00114-016-1376-xen
local.relation.doi10.1007/s00360-017-1060-2en
local.relation.doi10.1016/j.jtherbio.2011.11.007en
local.school.graduationSchool of Environmental & Rural Scienceen
local.search.authorWacker, Christineen
local.search.supervisorGeiser, Fritzen
local.search.supervisorKoertner, Gerharden
local.uneassociationYesen
local.atsiresearchNoen
local.sensitive.culturalNoen
local.year.conferred2017-
local.subject.for2020310910 Animal physiology - systemsen
local.subject.for2020410401 Conservation and biodiversityen
local.subject.seo2020280102 Expanding knowledge in the biological sciencesen
local.subject.seo2020180606 Terrestrial biodiversityen
local.profile.affiliationtypeUNE Affiliationen
local.profile.affiliationtypeUNE Affiliationen
local.profile.affiliationtypeUNE Affiliationen
Appears in Collections:School of Environmental and Rural Science
Thesis Doctoral
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