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BIO120 Animals at the Extremes Unit 1: The Desert Environment-OPEN University
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Open University
S324_1 14 Hours
Intermediate
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Course Description
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. Once you
have completed this unit, you will be all the more able to appreciate
the linked units that follow,
Animals at the extreme: hibernation and torpor (S324_2)
and
Animals at the extreme: the polar environment (S324_3)
. These units build on and develop some of the science you will study here.
By the end of this unit you should be able to:
- define and use, or recognise definitions and applications of, each of the bold terms;
- provide examples that show there is a continuum of desert climates and environments that link to diversity of flora and fauna;
- explain, with examples, the thermoregulatory strategies of evaders, evaporators and endurers, and interpret relevant data;
- describe
the importance of integration of behaviour, anatomy, physiology and
biochemistry in the study of animals that live in deserts;
- explain
physiological mechanisms of water conservation and cooling in named
evaders, evaporators and endurers, and interpret relevant data;
- recognise
potential ambiguity and uncertainty in attributing observed
physiological or biochemical features and responses to high T
a and aridity to genotypic adaptation, phenotypic plasticity or acclimatisation;
- explain
how the role of heat-shock proteins (Hsps) in cellular responses to
temperature extremes links to the molecular mechanism for control of
transcription of Hsp genes and interpret blots that track Hsp transcription;
- explain
the use of integration across related species in designing and
interpreting experiments to investigate whether features such as basal
metabolic rate (BMR) and reduced total evaporative water loss (TEWL) in
desert species are adaptive, or are derived from phylogenetic
constraints or phenotypic flexibility.
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Introduction
 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
- 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
- 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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There are currently no items in this folder.
Copyright 2007,
by the Contributing Authors.
Cite/attribute Resource.
administrator. (2010, January 03). BIO120 Animals at the Extremes Unit 1: The Desert Environment-OPEN University. Retrieved March 10, 2010, from Free University Courses OCW Courses OpenCourseWare Freeversity Foundation Web site: http://freeversity.org/science-and-mathematics/biology/bio120-animals-at-the-extremes-unit-1-the-desert-environment.
This work is licensed under a
Creative Commons License
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