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Time: 14 hours
Level: Intermediate
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 Introduction Resource- This unit is the first in a series of three on Animals at the extreme. It is concerned with the integration of behaviour anatomy, physiology and biochemistry in diverse vertebrates that live in deserts....
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| | 1 The desert climate: an introduction
- 1 The desert climate: an introduction Resource
- If you have visited a desert you will have noticed the sparse plant cover, or in certain sandy deserts, the almost complete absence of plant life. The low productivity of deserts derives from their defining...
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| | 2 Environments and populations
- 2.1 Introduction Resource
- The unique climate and topography of each desert links to the unique and characteristic flora and fauna found there. From the brief description of deserts provided in Section 1, you can appreciate that...
- 2.2 How animals interact with the environment is affected by their body size Resource
- Willmer et al. (2000) classify desert animals in terms of the range of body sizes and the rate of evaporation (Figure 8).
- 2.3 Behavioural strategies of evaders Resource
- Small animals, classified as evaders, include desert amphibians and reptiles, and also mammals, rodents and insectivores. The term ‘evaders’ refers to the animals’ behaviour, which helps to prevent overheating...
- 2.4 Behavioural strategies of evaporators Resource
- Willmer (2000) defines evaporators as animals that depend on sufficient water intake to enable them to cool T
b by evaporation. Few of these species can survive in deserts, and those that do either...
- 2.5 Behavioural strategies of endurers Resource
- Endurers are defined as large desert mammals such as oryx and camel, and large desert birds, ostrich and emu. The term ‘endurers’ suggests that these animals are forced to endure the extreme conditions...
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| | 3 Integrating across levels of analysis
- 3.1 Introduction Resource
- In mammals and birds, homeostasis, the provision of a stable internal environment, includes keeping certain physiological variables, T
b, cellular and extracellular water and blood glucose at near...
- 3.2 Integration of anatomy and behaviour with biochemical and physiological strategies in evaders Resource
- We know from Section 2.3 that small desert rodents remain cool by staying in their burrows for all or part of the day. Kangaroo rats (Dipodomys spp.; see Figure 20 in Section 2.3) depend on metabolic water...
- 3.3 Integration of anatomical features and biochemical and physiological strategies in evaporators Resource
- Birds and larger desert mammals that use evaporative cooling risk dehydration because of the difficulty of finding sufficient drinking water. For mammals, evaporative heat loss includes panting and sweating....
- 3.4 Integration of anatomical features and biochemical and physiological strategies in endurers Resource
- The endurers, large animals with a relatively low surface area: volume ratio, have problems in losing heat from the body when exposed to high T
a. Certain large lizard species behave like endurers,...
- Summary of Section 3 Resource
- Behavioural mechanisms for reducing water loss are integrated with physiology. While Dipodomys rests in a cool burrow, the nasal counter-current heat exchanger cools exhaled air, conserving water vapour...
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| | 4 Integrating across disciplines
- 4.1 Heat-shock proteins Resource
- Molecular biology provides further insights into the biochemical and physiological responses of vertebrates to extreme temperatures and aridity in the desert environment. Animals living in hot deserts...
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| | 5 Integrating across species
- 5 Integrating across species Resource
- Populations of related species occupy similar niches in different environments. A big question for environmental physiologists is whether differences in biochemistry and physiology between related species...
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| | 6 Phylogeny and cladistic analysis
- 6 Phylogeny and cladistic analysis Resource
- In Section 3.3 the point was made that many physiologists consider that desert birds are successful because of their avian physiology, not because of any specific adaptations. While Williams and Tieleman's...
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- 7 Conclusion Resource
- In this unit we have studied animals in the context of their own habitat rather than using the traditional comparative physiology approach of comparing organ systems in different species. Although we have...
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- Questions Resource
- Figure 48 illustrates the activity of the antelope ground squirrel Ammospermophilus leucurus during a typical day in the Nevada desert.
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| | References and Acknowledgements | |
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