Chapter 1 Summary
Key Takeaways
- Evolution Is a Scientific Theory Explaining Life’s Diversity: Evolution is the well-supported scientific theory that explains how populations change over generations through inherited traits. It accounts for the origin, diversity, and interconnectedness of all life forms via common ancestry, not as speculation, but as evidence-based science supported by genetics, fossils, anatomy, and molecular biology.
- Fossil Discoveries Challenged the Idea of Static Species: The belief that species were fixed was overturned by fossil evidence of extinct organisms like mastodons, ammonites, and ichthyosaurs. These findings led early naturalists to conclude that species could indeed change or disappear, laying the groundwork for theories of evolution.
- Darwin’s Observations on the HMS Beagle Led to Natural Selection: During his voyage, Darwin observed how species like finches, tortoises, and marine iguanas had adapted to different environments. These insights, influenced by geological and economic theories, led him to propose natural selection—the process by which advantageous traits become more common over generations.
- Multiple Lines of Evidence Support Evolution and come from:
- Fossils showing gradual changes in species over time
- Comparative anatomy revealing homologous and vestigial structures
- Biogeography demonstrating species distributions explained by plate tectonics
- Embryonic development shows similar stages among related species
- Genetic similarities across all life, confirming common ancestry
- Evolution Proceeds Through Multiple Mechanisms: Besides natural selection, evolution is driven by:
- Mutations: Random genetic changes
- Genetic drift: Random changes in small populations
- Gene flow: Migration of individuals/genes between populations
- Natural Selection Shapes Populations in Diverse Ways and can result in:
- Stabilizing selection: Favouring average traits.
- Directional selection: Shifting traits in one direction
- Disruptive selection: Favouring extremes
- Frequency-dependent selection: Favouring traits based on how common they are
- Sexual selection: Favouring traits that improve mating success
OpenAI. (2025). ChatGPT. [Large language model]. https://chat.openai.com/chat
Prompt: Summarize the following content into six key takeaways.
Flashcards
Text Description
Front of card:
- Fossils
- Charles Lyell
- Diversifying or disruptive selection
- Marsupials
- Ichthyosaurus
- Types of structures examined in comparative anatomy
- Vestigial structures
- Sexual dimorphism
- Founder effect
- Sexual selection
- Alfred Russel Wallace
- Continental drift
- Analogous structures
- Frequency-dependent selection
- Giant tortoises
- Piloerection
- Genetic drift
- Homologous structures
- Charles Darwin
- Tetrapods
- Evidence of Evolution
- Evolution
- Outcomes of natural selection
- Overproduction
- Mastodon
- Stabilizing selection
- Natural selection
- DHMS Beagle
- Adaptation
- Requirements of natural selection
- Types of Genetic Drift
- Heritability
- Marine iguanas
- Mutation
- Variation
- Thomas Malthus
- Jean-Baptiste Lamarck
- DFinches
- Ammonites
- DGalápagos Islands
- Directional selection
- Biogeography
- Mechanisms of Evolution
- DGene flow
- Bottleneck effect
- Selective pressure
- Genetic variation
Back of card:
- Preserved remains or traces of ancient organisms provide evidence for evolution
- A geologist who argued that the Earth changes slowly over time influenced Darwin’s thinking
- Natural selection that favours both extremes of a trait; intermediate phenotypes are often less fit
- Mammals with pouches; their distribution supports ideas of continental drift and evolution
- An extinct marine reptile; its fossil helped prove that extinction is real
- Homologous structures, analogous structures, and vestigial structures
- Body parts that have lost their original function through evolution
- Differences in appearance between males and females of the same species, often due to sexual selection
- Genetic drift occurs after a small number of individuals colonize a new area, leading to different allele frequencies
- Type of natural selection that occurs when individuals with certain traits are more likely to attract mates and reproduce
- Independently developed a theory of natural selection similar to Darwin’s
- The movement of Earth’s continents explains patterns in fossil and species distribution
- Body parts with similar function but different structure resulting from convergent evolution
- Type of natural selection that favours phenotypes that are either common or rare
- Galápagos animals with varied shell shapes and beak lengths; helped Darwin see adaptation to the environment
- Hair standing up (e.g., goosebumps); a vestigial response in humans
- A mechanism of evolution due to random changes in allele frequencies, especially in small populations
- Body parts with similar structure but different functions show common ancestry
- Developed the theory of evolution by natural selection
- Four-limbed vertebrates; their forelimbs are homologous structures
- 1) Fossils, 2) Comparative Anatomy, 3) Biogeography, 4) Embryonic Development, 5) Genetic Evidence
- The change in the genetic makeup of populations over generations, often resulting in new species
- Stabilizing Selection, Directional Selection, Disruptive Selection
- More offspring are produced than can survive, leading to competition
- An extinct relative of elephants; fossil evidence helped support the idea of extinction and change over time
- Natural selection that favours an average phenotype, selecting against extreme variation
- The process by which individuals with favourable traits are more likely to survive and reproduce
- The ship on which Darwin travelled and made observations that led to his theory of evolution
- A heritable trait that improves an organism’s ability to survive and reproduce in its environment
- Variation, Heritability, Differential Reproductive Success
- Bottleneck effect, Founder effect
- The ability of a trait to be passed from one generation to the next
- Galápagos reptiles that swim and feed in the ocean; helped Darwin see adaptation to the environment
- A change in DNA, the source of new genetic variation
- Differences among individuals in a population; essential for natural selection
- An economist who proposed that populations grow faster than resources, influenced Darwin
- Proposed an early theory of evolution involving the inheritance of acquired traits
- Birds from the Galápagos Islands; differences in their beaks helped Darwin develop his theory of natural selection
- Extinct marine mollusks with spiral shells; their fossils suggested that species can go extinct
- The location where Darwin observed unique species that influenced his ideas on evolution
- Natural selection that selects for phenotypes at one end of the spectrum of existing variation
- The study of where organisms live supports evolution through geographic distribution
- Mutations, Genetic Drift, Gene Flow, Natural Selection
- Movement of genes between populations; can introduce new traits
- Genetic drift that occurs when a chance event causes a sharp reduction in population size, reducing genetic diversity
- Environmental factors that influence which individuals in a population survive and reproduce; e.g. predators, climate, food availability, or competitio
- The differences in DNA sequences among individuals in a population, which lead to differences in traits, provide the raw material for natural selection to act upon
OpenAI. (2025). ChatGPT. [Large language model]. https://chat.openai.com/chat
Prompt: Provide definitions for all the bolded terms in the shared content and list all the terms in alphabetical order.
