Summary
Selection and evolution involve processes that lead to the development of new species and changes in populations over time.
- Species — A group of organisms that can interbreed and produce fertile offspring. Example: Lions and tigers are different species because they do not naturally interbreed.
- Gene Pool — The total collection of genes and alleles in a population. Example: The gene pool of a rabbit population includes all the alleles for fur color.
- Natural Selection — The process where organisms with favorable traits are more likely to survive and reproduce. Example: Brown-furred rabbits surviving better than white-furred rabbits due to camouflage.
- Speciation — The formation of new and distinct species in the course of evolution. Example: Allopatric speciation occurs when a geographical barrier divides a species.
- Reproductive Isolation — When different species live in the same area but cannot interbreed. Example: Different bird species may have different mating calls, preventing interbreeding.
Exam Tips
Key Definitions to Remember
- Species
- Gene Pool
- Natural Selection
- Speciation
- Reproductive Isolation
Common Confusions
- Confusing natural selection with evolution; natural selection is a mechanism of evolution.
- Thinking allopatric and sympatric speciation are the same; they differ by geographical barriers.
Typical Exam Questions
- What is the best measure of evolutionary fitness of an individual in a population? Its success in contributing genes to future offspring
- In order for speciation to occur, what must be true? At least one gene, affecting at least one phenotypic trait, must change.
- Which phylogenetic tree represents the evolution of species X, Y, and Z? Tree C
What Examiners Usually Test
- Understanding of the mechanisms of natural selection
- Ability to explain the process of speciation
- Knowledge of factors leading to reproductive isolation