pre+ib+Test+Review

Section 1: Evidence for Evolution

  • Fossil Record

    • Provides historical evidence of organisms that existed in the past.

    • Shows changes in species over time through transitional fossils.

    • Examples of ancient species resemble modern ones, indicating evolutionary paths.

  • Homologous Structures

    • Anatomical features in different species that share a common ancestry.

    • Example: The forelimbs of humans, whales, and bats have similar bone structures yet different functions.

  • Analogous Structures

    • Body parts in different species that perform similar functions but do not share a common ancestor.

    • Example: Wings of insects and birds used for flying, but structurally different.

  • Vestigial Structures

    • Body parts that have lost their original function through evolution.

    • Examples: The human appendix and wisdom teeth.

  • Embryology

    • Similarities in early embryonic development among different species provide evidence for a shared ancestry.

  • DNA and Protein Sequence Comparisons

    • Similarities in DNA and protein sequences among different organisms indicate evolutionary relationships.

Section 2: Natural Selection & Adaptation

  • Four Main Principles of Natural Selection

    1. Variation: Individuals in a population vary in traits.

    2. Inheritance: Traits are passed from parents to offspring.

    3. High Rate of Population Growth: Many offspring are produced, leading to competition.

    4. Differential Survival and Reproduction: Those with advantageous traits are more likely to survive and reproduce.

  • Adaptation

    • Natural selection leads to changes in a population over time, favoring traits that enhance survival and reproduction.

  • Survival of the Fittest

    • Refers to the idea that individuals best adapted to their environment are most likely to survive and reproduce.

  • Peppered Moth Example

    • Before industrialization, light-colored moths thrived; pollution darkened trees, leading to a rise in dark moths due to better camouflage, illustrating natural selection.

  • Genetic Variation

    • Essential for natural selection as it provides the material for evolution; diverse traits allow for adaptation to changing environments.

  • Antibiotic Resistance in Bacteria

    • Bacteria evolve resistance to antibiotics through natural selection, as only resistant variants survive exposure, leading to a population dominated by resistant strains.

Section 3: Darwin and His Influences

  • Darwin’s Observations on the Galápagos Islands

    • Noticed variations among species (e.g., finches) that seemed adapted to different environments and food sources.

  • Thomas Malthus' Influence

    • Suggested that population growth would outpace resources, leading to competition and struggle for survival, shaping Darwin’s ideas of natural selection.

  • Lamarck’s Theory of Evolution

    • Proposed the inheritance of acquired traits; discredited as traits acquired during an organism's life are not genetic.

  • Lyell’s Ideas on Earth's Age

    • His advocacy for deep time encouraged Darwin to consider that slow, gradual changes could result in evolution over long periods.

  • Alfred Wallace

    • Independently proposed natural selection; his work prompted Darwin to publish his theory, evidencing a collaborative scientific effort.

Section 4: Cladograms & Dichotomous Keys

  • Cladogram

    • A diagram showing evolutionary relationships among species based on shared characteristics.

  • Shared Derived Characteristic

    • A trait that is shared by a group of organisms but not present in their ancestors; used to define branches on a cladogram.

  • Dichotomous Key

    • A tool that allows scientists to identify organisms based on a series of choices that lead to the correct name; useful in taxonomy.

Section 5: Speciation & Evolutionary Processes

  • Speciation

    • The process by which one species splits into two or more separate species; often caused by isolation (geographic, behavioral, etc.).

  • Geographic Isolation

    • Physical barriers (e.g., mountains, rivers) that prevent populations from interbreeding, leading to the evolution of new species over time.

  • Convergent Evolution

    • Different species evolve similar traits due to similar environments; e.g., dolphins (mammals) and sharks (fish) have streamlined bodies.

  • Divergent Evolution

    • Related species evolve different traits due to different environments; e.g., Darwin’s finches.

  • Artificial Selection

    • Human-directed breeding of organisms for desired traits; differs from natural selection where environmental pressures determine survival.

  • Fitness

    • Refers to the reproductive success of an organism in passing its genes to the next generation; higher fitness means better adaptations to the environment.

Section 6: Important Definitions & Concepts

  • Adaptation

    • A trait that enhances an organism's ability to survive and reproduce in its environment; example: camouflage in prey species.

  • Difference Between Vestigial and Analogous Structures

    • Vestigial structures are remnants with no function (e.g., human tailbone), whereas analogous structures serve similar purposes but arise independently (e.g., wings of birds vs. insect wings).

  • Importance of Genetic Variation

    • Provides the raw material for evolutionary change, allowing populations to adapt to changing environments and pressures.

  • Mutation

    • A change in an organism's DNA that can introduce new traits; can be beneficial, harmful, or neutral, playing a critical role in evolution.

  • Difference Between Acquired and Inherited Traits

    • Acquired traits are gained during an organism's life and cannot be passed to offspring; inherited traits are genetic and passed down through generations.