Chapter 22: Darwinian Evolution
1. Compare and Contrast Evolution Theories
• Gradualism: Evolution occurs slowly over long periods.
• Catastrophism: Sudden catastrophic events cause mass extinctions, shaping evolution.
• Lamarckism: Organisms acquire traits during their lifetime and pass them to offspring (wrong theory).
• Darwin’s Natural Selection: Organisms with advantageous traits survive and reproduce, passing traits to offspring.
2. Acquired vs. Inherited Traits
• Acquired Trait: Gained during lifetime (e.g., muscle strength).
• Inherited Trait: Passed through genes (e.g., eye color).
3. Epigenetics
• Epigenetics shows how environmental factors can turn genes on or off without changing DNA.
• Combines Darwin’s natural selection (genes inherited) with Lamarck’s idea that environment influences traits.
4. Descent with Modification
• Species change over time, with descendants having different traits than ancestors due to natural selection.
5. Main Points of Darwin’s Theory
• Variation exists in populations.
• More offspring are produced than can survive.
• Individuals with advantageous traits survive and reproduce.
• Over time, populations change.
Examples:
• Antibiotic-resistant bacteria evolve because resistant bacteria survive and reproduce.
• Pesticide-resistant insects evolve when resistant individuals survive and reproduce.
6. Evidence for Evolution
• Biogeography: Distribution of species across the planet.
• Fossil Record: Shows transitional forms.
• Comparative Physiology: Similar structures in different species (homologous structures).
• Embryology: Similar embryonic development across species.
Chapter 23: Population Genetics
1. Population Genetics
• Combines Darwin’s natural selection with Mendel’s inheritance rules to explain evolution at the genetic level.
2. Natural Selection and Genetics
• Favorable alleles increase in frequency over time.
3. Hardy-Weinberg Theorem
• Describes a non-evolving population.
• Equation:
p^2 + 2pq + q^2 = 1
p + q = 1
• p = dominant allele frequency
• q = recessive allele frequency
• p² = homozygous dominant frequency
• q² = homozygous recessive frequency
• 2pq = heterozygous frequency
4. Practical Uses of Hardy-Weinberg
• Estimate allele frequencies in populations.
• Detect evolution in populations.
5. Allelic vs. Genotypic Frequencies
• Allelic: Frequency of specific alleles.
• Genotypic: Frequency of genetic combinations.
• Allelic frequencies can change without genotypic frequencies changing (if population is small).
6. Non-Evolving Population Conditions
• No mutations
• Random mating
• No natural selection
• Large population size
• No gene flow
7. Solving Hardy-Weinberg Problems
• Practice solving for allele and genotype frequencies.
8. Factors Causing Evolution
• Genetic Drift: Random changes in small populations (↓ Variability).
• Gene Flow: Movement of alleles between populations (↑ Variability).
• Mutations: New alleles arise (↑ Variability).
• Natural Selection: Favors certain traits (↓ or ↑ Variability).
9. Types of Natural Selection
• Directional: Favors one extreme trait (e.g., antibiotic resistance).
• Stabilizing: Favors intermediate traits (e.g., human birth weight).
• Disruptive: Favors both extremes (e.g., beak size in birds).
• Sexual Selection: Traits improve mating chances (e.g., peacock feathers).
• Artificial Selection: Humans breed for desired traits (e.g., dog breeding).
Disruptive Selection is most likely to lead to speciation.
10. Balanced Polymorphism
• Two or more traits maintained in a population (e.g., sickle cell trait).
11. Heterozygote Advantage
• Heterozygous individuals have higher fitness (e.g., sickle cell carriers resistant to malaria).
12. Microevolution vs. Macroevolution
• Microevolution: Small genetic changes in a population (e.g., antibiotic resistance).
• Macroevolution: Larger changes leading to new species (e.g., speciation).
Chapter 24: Speciation
1. Cladogenesis vs. Anagenesis
• Cladogenesis: Branching evolution (more diversity).
• Anagenesis: Gradual transformation without branching.
2. Reproductive Barriers
• Prezygotic: Prevent fertilization (e.g., behavioral isolation).
• Postzygotic: Prevent viable offspring (e.g., hybrid sterility).
3. Types of Speciation
• Allopatric: Physical barrier (e.g., squirrels separated by a canyon).
• Sympatric: No barrier (e.g., polyploid plants).
4. Punctuated Equilibrium: Rapid bursts of change.
• Adaptive Radiation: Rapid evolution into new niches (e.g., Darwin’s finches).
5. Convergent vs. Divergent Evolution
• Convergent: Unrelated species evolve similar traits (analogous structures).
• Divergent: Common ancestor leads to different traits (homologous structures).
Taxonomy & Phylogeny
1. Taxonomy: Classification of organisms.
• Phylogeny: Evolutionary history.
2. Phylogenetic Tree: Shows evolutionary relationships.
3. Three Domain System:
• Bacteria
• Archaea
• Eukarya
4. Dichotomous Key: Tool to identify organisms through a series of choices.
5. Shared Derived Characteristics: Traits unique to a clade.
6. Cladograms: Diagrams showing evolutionary relationships.
7. Groups on Cladograms:
• Monophyletic: Common ancestor and all descendants.
• Paraphyletic: Common ancestor but not all descendants.
• Polyphyletic: Unrelated organisms.
Miscellaneous Topics
1. Adaptations
• Plants: Cactus spines (water conservation).
• Animals: Camouflage in chameleons.
• Prokaryotes: Antibiotic resistance.
2. Selection Pressure
• Predation
• Climate
• Competition
• Disease
3. Symbiosis
• Mutualism (+/+): Bees and flowers
• Commensalism (+/0): Barnacles on whales
• Parasitism (+/-): Ticks on dogs
• Competition (-/-): Two species competing for the same resource
4. Coevolution: Two species evolve together (e.g., bees and flowers).
5. Adaptation Examples
• Chemical: Venom in snakes
• Aposematic Coloring: Bright colors in poison dart frogs
• Mimicry: Monarch vs. Viceroy butterflies
• Camouflage: Leaf insects
Knowt
