Biology Chapter on Natural Selection

Study Notes

Definition: A mechanism by which organisms with favorable traits are more likely to survive and reproduce, passing those traits to offspring.
Key Components:
- Variation: Differences in traits among individuals within a population.
- Heritability: Traits must be passed down from one generation to the next.
- Differential Survival: Individuals with advantageous traits survive and reproduce at higher rates.
Example: Peppered moths changing color during the Industrial Revolution due to pollution.

Definition: Differences in physical or behavioral traits among individuals of the same species.
Sources:
- Genetic Mutations: Changes in DNA that can introduce new traits.
- Environmental Factors: Influences such as climate, food availability, and habitat can affect traits.
Importance: It provides the raw material for natural selection to act upon.

Definition: Traits that enhance an organism's ability to survive and reproduce in a specific environment.
Types:
- Structural: Physical features (e.g., beak shape in birds).
- Behavioral: Actions taken by organisms (e.g., migration patterns).
- Physiological: Internal processes (e.g., temperature regulation).
Example: Cacti have thick skin and spines to conserve water in arid environments.

Definition: The change in inherited characteristics of biological populations over generations.
Mechanisms:
- Natural Selection
- Mutation: Random changes in DNA that can introduce new traits.
- Genetic Drift: Random changes in allele frequencies, especially in small populations.
- Gene Flow: Movement of genes between populations through migration.
Outcome: Can lead to speciation, where new species arise from existing ones.

Definition: The intentional breeding of organisms by humans for specific traits.
Examples:
- Domesticated animals: (e.g., dogs bred for specific behaviors or appearances).
- Crop plants: Selected for increased yield, taste, or disease resistance.
Contrast with Natural Selection: Driven by human choice rather than environmental pressures.

Definition: The struggle between organisms for limited resources such as food, space, and mates.
Types:
- Intraspecific Competition: Competition within the same species.
- Interspecific Competition: Competition between different species.
Effects on Populations: Can lead to adaptations, resource partitioning, or changes in population dynamics.

Definition: An ecological interaction where one organism (the predator) hunts another (the prey).
Dynamics:
- Regulation: Predators help regulate prey populations, preventing overpopulation.
- Adaptations: Prey develop adaptations (e.g., camouflage, speed) to evade predators.
- Co-evolution: As prey evolve defenses, predators may evolve better hunting strategies.
Example: Wolves hunting deer; an increase in wolves may lead to a decrease in deer population and vice versa.