
Lecture Archive
Natural Selection, Evolution, and Evolutionary Ecology
Presenter: James Danoff-Burg
Natural Selection, Evolution, and Evolutionary Ecology
James Danoff-Burg
Columbia University
Black Rock Forest, New York
Levels of Ecological Explanation
- Ultimate
- Proximate
- Human influences
- Abiotic changes
- Biotic interactions
Most ecologists explore the last three levels
Progress of Ecological Inquiry?
- Explore plausible ultimate answers
- If one is supported, stop
- If no ultimate answers are supported, explore proximate answers
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
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!
Evolution
- Change through time within a lineage
- Mechanisms / Producers of Variation
- Genetic drift
- Phenotypic plasticity
- Natural Selection
Natural Selection is not equal to Evolution
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
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
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
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
Planning - To be Determined:
- Environmental variable
- Experimental organism
- Organismal trait for study
- Statistical technique to use, justify