BIOL 359 Final Notes - Evolution

BIOL 359 Final Notes - Evolution (University of Waterloo)

• Fact: A repeatedly confirmed observation, accepted as true.
• Hypothesis: A tentative statement about the natural world, leading to testable deductions/predictions.
• Law: A descriptive generalization about how a natural phenomenon behaves under specific conditions.
• Theory: A well-substantiated explanation of a natural phenomenon, incorporating facts, laws, and tested hypotheses.
• Evolution: A scientific fact and theory, repeatedly confirmed; a well-substantiated explanation for the fact of evolution.
• Catastrophism: The historical belief that Earth's features were formed by catastrophic events.
• Uniformitarianism: The principle that geological processes occurring today are the same as those in the past.
• Lamarckism: A flawed early theory of evolution based on inheriting acquired characteristics.

Evolution History - Before Darwin

• ~500 BC Anaximander: Believed species originated from water, with humans descending from fish.
• ~400 BC Empedocles: Proposed that body parts randomly joined, and only successful combinations survived.
• ~300 BC Plato: Developed the concept of idealism, arguing that observed phenomena are imperfect representations of ideal forms.
• ~300 BC Aristotle: Visualized a static world with fixed species arranged on a Scala Naturae (scale of nature).
• 1735 Carolus Linnaeus: Developed the binomial nomenclature system for classifying organisms.

Evolution History - Before Darwin (continued)

• 1809 Jean-Baptiste Lamarck: One of the first to propose that evolution occurs over time, though his mechanism (inheritance of acquired characteristics) was flawed.
• 1794 Erasmus Darwin: Published Zoonomia, proposing species evolved and are descendants of earlier life forms; although he lacked evidence for natural selection.
• 1801 Georges Cuvier: Father of comparative anatomy and paleontology; proposed catastrophism and was among the first to recognize extinction events.

Evolution Before Darwin (continued)

• 1785 James Hutton: Proposed uniformitarianism, arguing that geological forces operate today as they did in the past.
• 1830 Charles Lyell: Published Principles of Geology, emphasizing uniformitarianism and contributing to the shift away from catastrophism.
• 1859 Charles Darwin: Published On the Origin of Species, outlining his theory of evolution by natural selection.

Modern Synthesis/Neo-Darwinian Synthesis

• The modern synthesis integrated Darwin's natural selection with Mendelian genetics.
• The synthesis established selection acting on genetic variation driving evolution across multiple levels (population to higher taxonomic).

Evidence for Evolution

• Descent with modification: The change in population allele frequencies over time.
• Homology: Similar characteristics from shared ancestry, functionally different.
• Analogy: Similar functions, but unrelated ancestry.

Selective Breeding

• Evidence for evolutionary change.
• Demonstrates that biological change is possible and can occur rapidly.
• Supports the idea that species evolve.

Incipient Species

• Populations that are nearly complete their separation into new species.

Vestigial Structures

• Body parts with reduced function compared to relatives, supporting evolutionary history.

Fossil Records

• Collection of fossils, providing evidence of evolution (change over time and relationship among species).
• Used for hypothesis testing regarding evolution.
• Demonstrates that organisms change over time and extinct species are similar to extant species.

Genetic Variation

• Classical Hypothesis: Little variation, selection for "best" alleles, rapid removal of deleterious mutations.
• Balancing Hypothesis: Heterozygosity at many loci maintained by balancing selection.
• Population Heterozygosity: Proportion of heterozygotes in a population.
• Selectionist Hypothesis: Balancing selection maintaining vast genetic variability, heterozygotes have higher fitness.
• Neutral Hypothesis: Most alleles are neutral (no effect on fitness).

Hardy-Weinberg Principle

• Shows how allele and genotype frequencies behave in natural populations if no external forces are acting, mating is random, and populations are large.
• Provides expected genotype frequencies for hypothesis testing.
• To determine whether a population is in Hardy-Weinberg equilibrium, use observed heterozygosity and expected heterozygosity to compare data.

Units 3, 4, Mutations, Phylogenetics

• Natural Selection: Difference in survival and reproduction of phenotypes leading to population changes.
• Evolutionary Fitness (Darwinian Fitness): Individuals' contribution/impact to the next generation, number of offspring.
• Adaptation: Traits increasing relative fitness.
• Antagonistic Selection: Different selective pressures favoring different traits.
• Adaptation: Trait increasing fitness compared to individuals without it
• Genetic Variation: Differences in traits due to genetic differences within individuals (genotype).
• Environmental Variation: Different traits arising from environmental conditions, despite identical genotypes.
• Mutation: Changes in DNA sequences-Substitutions, insertions, deletions, and frameshifts (point, nonsense, transition, transversion).
• Indels (Insertions and Deletions): Changes in DNA sequence involving one or more nucleotides, can lead to huge shifts.
• Neutral, Deleterious, Beneficial, Lethal Mutations: Affect fitness in different ways.
• Homologous Structures: Similar in structure but different function, due to shared ancestry.
• Homoplasy: Analogous traits that arose independently.
• Phylogenetics: Study of ancestor-descendant relationships.
• Transitional Forms: Intermediate forms that blend features of ancestral and descendant forms.

Units 7 - 11, 14

• Adaptation: Trait increasing fitness.
• Trade-off: Compromises in traits.
• Constraint: Factors slowing adaptation.
• Parthenogenesis: Asexual reproduction— Obligate (cloning) and cyclical (some sexual reproduction)
• Hermaphrodites: Organisms with both sex organs; capable of self-fertilization.
• Parental Investment: Effort for mating, gestation, and caring for offspring.
• Sexual Selection: Differential reproductive success.
• Sexual Dimorphism: Differences in appearance between sexes.
• Intrasexual Selection: Within-sex competition.
• Intersexual Selection: Between-sex choice.
• Kin Selection: Altruism toward relatives, increasing inclusive fitness.
• Coefficient of Relatedness: Degree of genetic similarity between individuals.
• Hamilton's Rule: When rB >C (coefficient of relatedness * benefit > cost), altruism is favored.
• Species Concepts: Morphological (physical similarities), Biological (interbreeding), and Phylogenetic (shared evolutionary history), Cryptic Species, Hybridization.
• Biogeography: Geographic distribution of organisms.
• Dispersal: Movement of organisms away from their origin.
• Vicariance: Formation of a physical barrier separating populations.
• Endemic: Species found only in a particular region.
• Punctuated Equilibrium: Evolution characterized by rapid bursts of change followed by periods of stasis.
• Phyletic Gradualism: Morphology changes slowly over time.
• Human Evolution Timeline: Divergence from chimpanzee ancestors 5-7 million years ago.