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Variation and Adaptation
• Define the term variation
• Discuss the fact that variation occurs within
as well as between species
• Describe the differences between
continuous and discontinuous variation, using
examples of a range of characteristics found
in animals, plants and microorganisms
• Explain both the genetic and environmental
causes of variation
• Outline the behavioural, physiological and
anatomical (structural) adaptations of
organisms to their environment.
• Variation - the presence of
variety/differences between individuals.
• Variation can occur within a species or
between species.
Continuous variation
• There are two
extremes and a full
range of
intermediates.
• Most individuals are
close to the mean
value.
• The number of
individuals at the
extremes are low.
• Height in humans
• Length of leaves on a
tree.
Discontinuous variation
• Two or more distinct
categories with no
intermediate values.
• Members of a
species may be
evenly or unevenly
distributed between
categories.
• Sex – M or F
• Human blood groups
– A, O, B, AB
Causes of variation
• Can be inherited or environmental.
• Use page 211 to explain how variation can be
inherited or caused by the environment.
Adaptation to the Environment
An adaptation is a
feature that enhances
survival and long term
reproductive success.
A well adapted organism will be able to:
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•
•
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Find enough food or photosynthesise well
Find enough water
Gather enough nutrients
Defend itself against predators and diseases
Survive the physical conditions of its
environment such as changes in temperature,
light and water levels
• Respond to changes in its environment
• Have enough energy left over to reproduce
successfully.
Behavioural Adaptations
Physiological Adaptations
Anatomical Adaptations