Evolution, Ecology, and Complex Adaptive Systems
Evolution as a Population Process
Selection, Drift, and Constraint
Evolution is change in heritable variation across generations. Advanced evolutionary science distinguishes adaptation from drift and recognizes the roles of developmental constraint, epistasis, gene flow, and changing environments in shaping evolutionary trajectories.
Population Thinking
Evolution acts on distributions of traits, not on idealized averages alone.
What best describes genetic drift?
Genetic drift is stochastic fluctuation in allele frequencies, strongest in small populations.
Correct answer: Random change in allele frequencies, especially in small populations
What is an ecological niche?
A niche includes both abiotic and biotic interactions, not just habitat.
Correct answer: The functional role and resource-use pattern of a species in its environment.
Selection vs Drift
Natural selection
- Nonrandom differential reproductive success
- Requires heritable variation
- Can produce adaptation
Genetic drift
- Random sampling effects
- Strong in small populations
- Can reduce diversity without adaptation
Ecological Interactions
| Interaction | Example Consequence |
|---|---|
| Competition | Reduced resource availability |
| Predation | Population cycling |
| Mutualism | Increased fitness for both partners |
| Parasitism | Fitness cost to host |
Which metric is commonly used to describe species diversity while accounting for richness and evenness?
Entropy-based indices combine richness and evenness into a single diversity measure.
Correct answer: Entropy-based diversity index
Why are ecosystems considered complex adaptive systems?
Feedback, adaptation, and emergent patterns define complex adaptive systems.
Correct answer: They contain interacting agents whose collective behavior changes over time.
Studying an Evolving Ecosystem
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1
Define the population or community boundary.
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2
Measure trait frequencies, interactions, and environmental variables.
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3
Model change under selection, drift, and migration.
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4
Test predictions against temporal or spatial data.
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5
Assess resilience, stability, and tipping points.