Animals that inhabit unfavourable habitats and experience seasons where the cost of maintenance exceeds the available energy resources have over time developed behavioural and physiological mechanisms to survive. These adaptations include changes in activity, improvement of cold tolerance by using nonshivering thermogenesis (NST), improvement of thermal conductance, reduction of body mass, or acclimation to colder temperatures (reduction of metabolic requirement). In addition some species exhibit heterothermy, in the form of either daily torpor or longer-term hibernation. The southern African hedgehog (Atelerix frontalis) is an excellent candidate to investigate the phenomenon of heterothermy because it is a small insectivore (summer body mass ca. 300 to 400g), burrows, inhabits harsh habitats and is not easy to find during the winter months. In this study I aimed to investigate whether A. frontalis exhibits seasonal differences in metabolic rate and furthermore if this species exhibits heterothermy. The study was carried out in the Northern Cape Province, South Africa. Hedgehogs were hand captured and their metabolic rates were measured using indirect calorimetry. Individuals were implanted with temperature dataloggers for a summer period (November 2009-January 2010) and a winter period (May-August 2009). The summer BMR of adult A. frontalis (0.448 ±0.035 mlO2/g/h, n=4) was significantly lower than their winter BMR (0.811 ±0.073 mlO2/g/h, n=4) and statistical analyses revealed that this was an affect caused by seasonal changes in the ambient environment. Individuals spent up to 84 percent of time during the measurement period torpid (-8°C <Ta<21°C). Body mass appears to be an important factor in determining the pattern of heterothermy (daily torpor versus hibernation) used in this species. To my knowledge the extremely low body temperature (Tb min) of 1.0°C recorded for A. frontalis is the lowest Tb min recorded for a mainland Afrotropical mammal. This species displays classic up-regulation in metabolic rate during winter, resulting in an increase in the energetic requirements of the species. As a result, heterothermy appears to play a significant role in the energy balance of this species during winter, contributing to energy saving. Heterothermy may enable this species to survive in the face of global climate change.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nmmu/vital:10683 |
| Date | January 2011 |
| Creators | Hallam, Stacey Leigh |
| Publisher | Nelson Mandela Metropolitan University, Faculty of Science |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Masters, MSc |
| Format | v, 56 leaves : ill. (chiefly col.), col. maps, pdf |
| Rights | Nelson Mandela Metropolitan University |
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