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