AP Bio things to know evolution

Chapter 22: Descent with Modification

1. Vocabulary:

   • Evolution: Change in the genetic composition of a population over generations.

   • Adaptation: Inherited characteristics that enhance survival and reproduction in a specific environment.

   • Natural Selection: Process where individuals with beneficial traits survive and reproduce more successfully.

   • Artificial Selection: Selective breeding by humans to promote desirable traits.

   • Homologous Structures: Anatomical structures in different species with similar structures but different functions, indicating common ancestry.

   • Vestigial Structures: Structures that serve little or no function but were useful to ancestors.

2. Hutton and Lyell's Influence on Darwin:

   • Hutton proposed gradualism, suggesting Earth's features formed over long periods.

   • Lyell’s uniformitarianism stated geological processes are constant over time, leading Darwin to infer that small changes accumulate over vast timescales.

3. Lamarck’s Theory:

   • Use and Disuse: Body parts used extensively become stronger; unused parts deteriorate.

   • Inheritance of Acquired Characteristics: Traits acquired during an organism’s life could be passed to offspring.

   • Innate Drive for Complexity: Organisms evolve toward greater complexity.

4. Pre-Darwin Beliefs:

   • The Earth was thought to be only a few thousand years old.

   • Populations were believed to be unchanging.

5. Darwin’s Observations and Inferences:

   • Observations:

     • Organisms produce more offspring than can survive.

     • Individuals vary in traits.

     • Traits are heritable.

   • Inferences:

     • Individuals with beneficial traits leave more offspring.

     • Favorable traits accumulate in populations over generations.

6. Key Features of Natural Selection:

   • Variation in traits exists.

   • Traits are inherited.

   • More offspring are produced than can survive.

   • Individuals with advantageous traits survive and reproduce.

7. Sequence of Evolutionary Events: b → d → a → c

   • A change in the environment occurs.

   • Poorly adapted individuals decrease in number.

   • Well-adapted individuals reproduce more.

   • Genetic frequencies shift over generations.

8. Evolutionary Tree Interpretation:

   • Shows common ancestors.

   • Branch points indicate speciation events.

   • Organisms with closer branches share a more recent ancestor.

Chapter 23: Evolution of Populations

1. Vocabulary:

   • Gene Pool: Total genetic diversity within a population.

   • Allele Frequency: Proportion of a specific allele in a population.

   • Genetic Drift: Random changes in allele frequencies.

   • Founder Effect: Small group isolates and starts a new population with different allele frequencies.

   • Bottleneck Effect: Sudden population reduction causes loss of genetic diversity.

   • Gene Flow: Movement of alleles between populations.

   • Relative Fitness: Individual’s reproductive success relative to others.

2. Sources of Genetic Variation:

   • Mutations: Random changes in DNA.

   • Sexual Reproduction:

     • Independent Assortment: Random separation of chromosomes.

     • Crossing Over: Exchange of genetic material during meiosis.

     • Random Fertilization: Sperm and egg combinations vary.

3. Hardy-Weinberg Equilibrium:

   • A population in genetic equilibrium does not evolve.

   • Conditions:

     1. No mutations.

     2. Random mating.

     3. No natural selection.

     4. Large population size.

     5. No gene flow.

4. Hardy-Weinberg Equations:

   • Allele Frequency: p+q=1p + q = 1p+q=1

   • Genotype Frequency: p2+2pq+q2=1p^2 + 2pq + q^2 = 1p2+2pq+q2=1

   • Solve q2q^2q2 first to find other values.

5. Natural Selection Types:

   • Directional: Favors one extreme.

   • Disruptive: Favors both extremes.

   • Stabilizing: Favors intermediate traits.

6. Antibiotic, Pesticide, and Herbicide Resistance:

   • Mutations create resistant traits.

   • Natural selection increases resistant individuals.

Chapter 24: Origin of Species

1. Vocabulary:

   • Species: Group of interbreeding individuals producing viable offspring.

   • Speciation: Process by which new species form.

   • Reproductive Isolation: Barriers preventing gene flow between species.

   • Punctuated Equilibrium: Rapid bursts of change followed by stability.

2. Biological Species Concept & Limitations:

   • Species = organisms that can breed and produce fertile offspring.

   • Limitations: Does not apply to asexual organisms or fossils.

3. Phylogenetic Species Concept:

   • Species are defined by evolutionary history and common ancestors.

4. Reproductive Barriers:

   • Prezygotic (before fertilization): Habitat, temporal, behavioral, mechanical, gametic isolation.

   • Postzygotic (after fertilization): Hybrid inviability, hybrid sterility, hybrid breakdown.

5. Allopatric vs. Sympatric Speciation:

   • Allopatric: Geographic separation leads to speciation.

   • Sympatric: New species form without physical separation.

6. Factors Leading to Sympatric Speciation:

   • Polyploidy: Extra chromosome sets.

   • Sexual Selection: Mate preference causes divergence.

   • Habitat Differentiation: Exploiting new ecological niches.

7. Hybrid Zone Outcomes:

   • Reinforcement: Strengthening reproductive barriers.

   • Fusion: Species merge.

   • Stability: Hybrid zone remains.

Chapter 25: History of Life on Earth

1. Vocabulary:

   • Radioactive Dating: Determines fossil age using isotopes.

   • Half-Life: Time for half of an isotope to decay.

2. Early Earth Atmosphere:

   • Least abundant gas: Oxygen (O₂).

   • Consisted of water vapor, nitrogen, CO₂, methane, ammonia.

3. Miller & Urey Experiment:

   • Simulated early Earth conditions.

   • Produced organic molecules, supporting abiogenesis.

4. Cyanobacteria:

   • First oxygen-producing organisms.

   • Led to oxygen-rich atmosphere.

5. Origin of Life Sequence: b → c → a → d

   • Organic monomers → Organic polymers → Protocells → DNA-based genetic systems.

6. First Genetic Material:

   • RNA, because it can store information and catalyze reactions.

7. RNA to DNA Transition:

   • DNA is more stable for storing genetic information.

8. Evolutionary Sequence: c → d → b → a

   • Photosynthetic prokaryotes → Mitochondria → Chloroplasts → Multicellular eukaryotes.

9. Endosymbiosis Evidence:

   • Mitochondria and plastids:

     • Have their own DNA.

     • Replicate like bacteria.

     • Have double membranes.

     • Contain ribosomes similar to prokaryotes.

10. Half-Lives & Fossils:

• 6.25% isotope remains → 4 half-lives elapsed.

11. Fossilization Likelihood:

• Hard-bodied species.

• Aquatic organisms.

• Buried quickly after death.

12. Earth’s Age: 4.6 billion years.

13. Oldest Fossils:

• 3.5 billion years old.

• Prokaryotic.

14. Key Evolutionary Events:

• 2.7 bya: Oxygen accumulation.

• 1.8 bya: Eukaryotic cells.

• 1.2 bya: Multicellular eukaryotes.