Title page for ETD etd-07182011-162503


Document Type Master's Dissertation
Author Streicher, Sonja
Email sstreicher@zoology.up.ac.za
URN etd-07182011-162503
Document Title The effect of environmental variables on patterns of body temperature in the Damaraland mole-rat, Fukomys damarensis (Ogilby 1838)
Degree MSc
Department Zoology and Entomology
Supervisor
Advisor Name Title
Dr F Dalerum Co-Supervisor
Prof N C Bennett Supervisor
Keywords
  • intrinsic factors
  • seasonality
  • soil temperature
  • locomotor activity
  • Fukomys damarensis
  • body temperature
  • iButtons
  • light
  • extrinsic factors
  • individual variation
Date 2011-04-07
Availability restricted
Abstract
Body temperature is an important physiological parameter that is determined by the manner in which an animal obtains its energy source and in turn relates to its immediate environment. Body temperature can be generated from within (endothermy) or may be derived from the environment (poikilothermy). We investigated body temperature patterns in free-ranging and captive Damaraland mole-rats using miniature data loggers (iButtons). We investigated the patterns of body temperature exhibited in free-ranging Damaraland mole-rats on a daily basis, as well as the influence of soil temperature and various intrinsic (sex and body mass) and extrinsic (season and ambient soil temperature) factors on body temperature. In captive animals we investigated the effect of light and locomotor activity on body temperature. Free-ranging Damaraland mole-rats regulated their body temperature at approximately 35 șC, which is consistent with previous recorded body temperatures in laboratory studies. Hourly frequency distributions of minimum and maximum temperatures differed between mole-rats and the soil surface, suggesting that body temperature was not closely linked to the soil surface temperatures. Instead, the relationship between the body temperature and soil temperatures was affected by complex interactions between the season experienced as well as the sex and body mass of the animal. The body temperatures of males were positively related to body mass while the relationship for females was negative. Our results further suggest that there were thermoregulatory differences between males and females during summer. In free-ranging Damaraland mole-rats, our analyses showed that the variation in patterns of body temperature was great among individual mole-rats, even within a single colony. Generally mole-rats did not exhibit marked daily body temperature rhythms as has been reported routinely for above ground rodents but rather the diel patterns were not distinct. Despite a wide range of body temperatures experienced during especially winter, Damaraland mole-rats may be considered generally as good thermoregulators and are best described as homeotherms. In captive Damaraland molerats, our results suggest that light generally influenced body temperatures through locomotor activity, but due to substantial individual variation it was difficult to generalize on these effects. Damaraland mole-rats mostly adopted a diurnal pattern of locomotory activity under a 12L:12D light cycle (12 hours light followed by 12 hours dark). Locomotor activity raised body temperatures more during the night (the inactive phase), than during the day (the active phase). Also, body temperature showed a time lag in its relation to locomotor activity and this time lag was affected by light conditions. Our study is one of the first studies to monitor body temperatures of a free-ranging southern African subterranean rodent species that is social and experiences a seasonal but much muted burrow temperature range. These findings accentuates the complex physiological response of mammals to environmental change, and underlines the range of variables, both intrinsic and extrinsic, that has to be controlled for when studying such relationships. Our study highlights the substantial individual variation in the physiological responses in this subterranean species to environmental cues, and we suggest that further research should focus on relating how individual attributes affect such intra-specific variation.

© 2010, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Streicher, S 2010, The effect of environmental variables on patterns of body temperature in the Damaraland mole-rat, Fukomys damarensis (Ogilby 1838), MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07182011-162503 / >

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