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Natural Selection, Evolution, and Evolutionary Ecology

Natural Selection, Evolution, and Evolutionary Ecology. Dr. James Danoff-Burg Columbia University. Levels of Ecological Explanation. Ultimate Evolutionary influences Proximate Human influences Abiotic changes Biotic interactions Most ecologists explore the last three levels.

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Natural Selection, Evolution, and Evolutionary Ecology

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  1. Natural Selection, Evolution, and Evolutionary Ecology Dr. James Danoff-Burg Columbia University

  2. Levels of Ecological Explanation • Ultimate • Evolutionary influences • Proximate • Human influences • Abiotic changes • Biotic interactions Most ecologists explore the last three levels

  3. Progress of Ecological Inquiry? • Explore plausible ultimate answers • If one is supported, stop • If no ultimate answers are supported, explore proximate answers

  4. Rationale • Need to pitch the question at the right level • Example • Why are Penguins only in the Southern Hemisphere? • Proximate - insufficient food, too many predators, lack of shelter, etc. • Ultimate - historical and thus evolutionary distribution --> favored at present

  5. Two EvolEcol Branches • Intraspecific • Relative selective value of different traits • Origin of intraspecific diversity • Interspecific • Behavioral ecology (comparative studies) • Systematics and phylogeny Common feature of all branches - Evolution!

  6. Evolution • Change through time within a lineage • Mechanisms / Producers of Variation • Genetic drift • Phenotypic plasticity • Natural Selection Natural Selection  Evolution

  7. Natural Selection • Proposed by Darwin and Wallace • Evolutionary mechanism • One way that variation exists and is maintained in a population • Value is relative to local competitors • Only a negative action • Only selection AGAINST a form of a trait • Never selection for a trait

  8. Intraspecific Variation • Possible sources: • Genetic drift • Phenotypic plasticity • Natural Selection • How to differentiate between them? • Genetic fixation / continuity through lineages • Use traits that do not change in response to changes in environment

  9. Today’s Activity • How do changes in a resource gradient affect intraspecific diversity? • Are these changes due to natural selection? • Choose an organism with the following characteristics: • Low vagility • Does not disperse aerially • Clearly marked adult stage • Traits under study do not change

  10. Activity Tasks • Plan activity • Collect data and enter into eBiome • Analyze our data • Wait for data from other sites • Jointly analyze all data • Make conclusions about relationship • Posit future studies to distinguish between evolutionary mechanisms

  11. Planning - To be Determined: • Environmental variable • Experimental organism • Organismal trait for study • Statistical technique to use, justify

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