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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: • • • • • 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