Overview
This lecture explains evolution as a change in the gene pool over time, highlighting the five main processes that cause evolution, remembered by the "five fingers" analogy.
Definitions and Basic Concepts
- Evolution is a change in the gene pool (all the genes in a population) over time.
- The gene pool consists of all the copies of each gene in a population.
- Genes are segments of DNA that determine traits.
The Five Fingers of Evolution
- Little Finger: Population shrinking causes random changes in gene frequency due to chance (genetic drift).
- Ring Finger: Non-random mating (mate choice) affects gene frequencies, such as assortative mating by traits or location.
- Middle Finger: Mutation introduces new genes or alleles, altering the gene pool.
- Pointer Finger: Movement or gene flow through immigration or emigration changes gene frequencies.
- Thumb: Natural selection favors genes that increase survival and reproduction, leading to adaptation.
Natural Selection and Adaptation
- Only natural selection leads to adaptation to the local environment.
- Adapted genes become more common; maladapted genes decrease.
- Example: Red hair and fair skin benefit northern climates (more vitamin D) but are disadvantageous in high UV environments.
Microevolution and Macroevolution
- Microevolution refers to small changes in the gene pool within a population.
- Over long periods, microevolution can lead to macroevolution (speciation).
- All organisms share a common ancestor through evolutionary processes.
Key Terms & Definitions
- Evolution — Change in the gene pool of a population over time.
- Gene Pool — The set of all genes and alleles in a population.
- Mutation — A change in DNA that introduces new genetic variations.
- Gene Flow — Movement of genes between populations via migration.
- Natural Selection — Process where advantageous traits become more common.
- Microevolution — Small-scale changes within a species.
- Macroevolution — Large-scale changes that can result in new species.
Action Items / Next Steps
- Review and memorize the five causes of evolution using the finger analogy.
- Consider how each process impacts genetic diversity.
- Prepare examples of each process for class discussion.