1. The difference between individuals of the same or different species
Variation
The difference between individuals of the same or different species

2. Objectives Be able to 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
Explain both genetic and environmental causes of variation
Outline the behavioural, physiological and anatomical adaptations of organisms to their environments.

3. Interspecific variation
Differences between individuals of different species are used as criteria for classification

4. Intraspecific
Within the same species there are differences

5. Causes of variation Genetic
The particular combination of alleles passed on by two parents by sexual reproduction.
Mutation during either sexual or asexual reproduction.
Environmental
Plant features are easily influenced by light, mineral nutrition, availability of water- especially the amount and direction of growth.
Animal features may be influenced by diet, temperature, and developmental environment.

6. Example of environmental variation

7. Two types of variation 1 Discontinuous variation
A few discrete categories no intermediate forms
Usually controlled by one gene
Less likely to be influenced by environment

8. Two types of variation 2 Continuous
There is a range of many intermediates between two extremes
Represented using a frequency histogram where the range has to be split up into classes
Controlled by the influence of several genes ( polygenic)