10-26-11 Adaptations 1

10-26-11 Adaptations 1 - ZOL 445 Evolution October 26, 2011...

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ZOL 445 Evolution October 26, 2011 Evolutionary Analysis: The Study of Adaptation I What is an adaptation? An adaptation is a phenotypic trait that confers a reproductive advantage on the organism bearing it. Adaptations are maintained by natural selection. Characteristics of an adaptation: Must be a heritable phenotypic trait, i.e. be genetically determined Must show (or have shown) genetic variation Some genetic variants must have (or have had) a selective advantage over others How to determine whether a trait is an adaptation? 1. Identify local trait 2. Identify what genetic variation trait may have 3. Hypothesize why particular genetic variants of the trait have a selective advantage. 4. Test the predictions of the hypothesis: a. Comparative method b. Experimental method c. Observational studies Identifying adaptations: Comparative Analysis Case study: Ant-tending in aphids o Ant-tending is beneficial to aphids… Aphids produce honeydew as a waste product from their sugar-rich diet of plant sap. Ants collect honeydew as a source of carbohydrates Ant-tending appears to be a mutualism between ants and aphids, with
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10-26-11 Adaptations 1 - ZOL 445 Evolution October 26, 2011...

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