Evolution Notes Part II Natural Selection Natural selection
- Slides: 15
Evolution Notes Part II
Natural Selection Natural selection has three modes of action: 1. Stabilizing selection 2. Directional selection 3. Disruptive selection
1. Stabilizing Selection Favors the average, acts against the extremes. Number of Individuals Small Large Size of individuals
2. Directional Selection Favors one of the two extremes. Number of Individuals Small Large Size of individuals
3. Disruptive Selection Favors both extremes, acts against the average. Number of Individuals Small Large Size of individuals
How do new species evolve? Speciation-the formation of new species In order for new species to form, there must first be reproductive isolation among parts of a population.
Isolating Mechanisms 1. Geographic Isolation 2. Behavioral Isolation 3. Temporal Isolation
Geographic Isolation Populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water.
Behavioral Isolation Populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding.
Temporal Isolation Two populations reproduce at different times.
Adaptive Radiation Emergence of numerous species from a common ancestor introduced to new and diverse environments.
Coevolution Evolutionary change resulting from the interaction between two different species. Example: Pollinators and Flowering plants
Biodiversity The sum total of different species in a given area.
Extinction
Interpretations of Speciation Two theories: 1. Gradualist Model (Neo-Darwinian): Slow changes in species over time. Punctuated Equilibrium: Evolution occurs in spurts of change. 2. relatively rapid
- Types of natural selection in evolution
- Genetic drift v gene flow
- Natural selection vs evolution
- Natural selection
- Similarities
- Natural selection vs artificial selection
- Artificial selection vs natural selection
- Stabilizing selection
- Natural selection vs artificial selection
- Evidence for evolution doodle notes
- Synthetic theory
- Neutral theory of molecular evolution notes
- Lamarck theory of evolution notes
- Organism
- Evolution of shrm
- The image below shows phiomia an ancestor of elephants