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Open University
S182_3 10 Hours
Introductory
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Course Description
All of the animals described in this unit are
members of the mammalian order Rodentia. The rodents are widely regarded
as amongst the most successful of all the mammalian groups. We will
examine some features of rodent biology that contribute to their
success, in particular their exploitation of a unique range of plant
foods, especially seeds, wood and roots. While focusing on rodent
feeding behaviour and reproduction, we will also be exploring some more
general ideas concerning the origin of the features that make an
important contribution to rodent success.
This is the third in a series of units about
studying mammals. To get the most from these units, you will need access
to a copy of The Life of Mammals (2002) by David
Attenborough, BBC Books (ISBN 0563534230), and The Life of Mammals (2002) on DVD, which
contains the associated series of ten BBC TV programmes. OpenLearn unit S182_8 Studying mammals: life in the trees
contains samples from the DVD set. You should begin each unit by
watching the relevant TV programme on the DVD and reading the
corresponding chapter in The Life of Mammals. You will be asked
to rewatch specific sequences from the programme as you work through the
unit.
By the end of this unit you
should be able to:
- explain the implications
of a seed/nut-eating habit;
- suggest
why rodents are a successful order of mammals;
- describe adaptation, based on knowledge of the theory
of biological evolution by natural selection;
- explain how altruistic characteristics can be
understood in terms of kin selection and inclusive fitness;
- give examples of the fitness costs and benefits
associated with different reproductive behaviours;
- illustrate the importance of environmental factors in
determining the mating system used.
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Introduction
 Introduction
Resource- All of the animals described in
this unit are members of the mammalian order Rodentia. The rodents are
widely regarded as amongst the most successful of all the mammalian
groups. We will examine some features...
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1 The rodent
- 1 The rodent
Resource
- As you work through this unit you
will come across boxes, like this one, which give you advice about the
study skills that you will be developing as you progress through the
unit. To avoid breaking up...
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2 You are what you eat
- 2.1 Overview
Resource
- In this section, you will meet
some new units, the units in which energy is measured. Nowadays, there
are internationally agreed units (called SI units) that are often used
in combination with a prefix...
- 2.2 Cracking nuts and other ways of
eating Resource
- This section returns to the
arrangement of teeth in the jaws of various mammals and uses the same
representation for the dental formula as used in S182_2 Studying
mammals: the insect hunters. You are not...
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3 Some principles that underpin evolutionary
change
- 3.1 Introduction Resource
- Section 3 consists of several
subsections of quite concentrated reading, describing some fundamental
principles of biology. It shows how biologists need to use language very
carefully and how commonly...
- 3.2 Adaptation Resource
- If you are working through the
units in this series in sequence, you have already been introduced to
the idea that many features of an animal's behaviour and structure are
adaptations to their way of life....
- 3.3 Variation Resource
- Fossil rodents are first found in
rocks that date from around 65 million years ago (from the Eocene) and
are thought to have evolved from insectivore/omnivore-type mammals that
lived 100 million years...
- 3.4 Competition Resource
- In plants it is particularly
obvious that many more potential offspring (seeds) are produced than can
survive. To a very large extent it is a matter of chance as to which
are the survivors. Some are eaten,...
- 3.5 Natural selection Resource
- Darwin summarised his theory of
natural selection in the introduction to The Origin of Species as
follows:
- 3.6 The numbers game … or the
struggle for existence Resource
- In the majority of The Life of
Mammals TV sequences there is relatively little evidence of any struggle
for existence, apart from the occasional predator/prey interaction.
Even then you are offered the...
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4 Individual lives: the concept of fitness
- 4.1 A measure of success Resource
- If what I have highlighted so far
were the whole story, the only adaptive features shown would be those
that equipped the rodent for times of famine, which is patently not the
case. It is obviously a very...
- 4.2 Altruism
Resource
- How is it possible then to sustain
groups in which some individuals are prevented from breeding? They
would have no lifetime reproductive success, none of their
characteristics could be passed on to offspring....
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5 Different reproductive strategies
- 5.1 Monogamy and polygamy Resource
- You've seen plenty of evidence
that reproduction in rodents – more precisely what I've called their
reproductive strategies – are versatile and varied. You'll appreciate
that ‘versatile and varied’ describes...
- 5.2 Differences between the sexes Resource
- In biology, ‘sex’ refers to a
particular form of reproduction, sexual reproduction, that is distinct
from asexual reproduction. As you know, sexual reproduction involves the
production of eggs by females...
- 5.3 The effect of environment on
reproductive behaviour Resource
- Review your reading of Section 4.2
on the family life of marmots (or reread LoM pp. 66–67) and construct
an argument to explain why polygamy may not be profitable for the male
marmot.
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6 Reflection
- 6 Reflection
Resource
- If you are working through all the
units in this series, you'll be aware that this unit has taken a
somewhat different tack from earlier ones. I've used rodents to explore
some fundamental biological principles...
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References and Acknowledgements
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