Evolution Test

Study Guide: Key Concepts in Evolution

Fossils

• What fossils show: Fossils provide evidence of past life forms, showing changes over time and helping us trace the evolution of species.

• Fossil record: Demonstrates transitions between species and provides a timeline of evolutionary history.

Natural vs. Artificial Selection

• Natural selection: Process where organisms better adapted to their environment survive and reproduce, passing on favorable traits.

• Artificial selection: Human-driven breeding for specific traits, such as in crops or domesticated animals.

Adaptations

• Definition: Traits that increase an organism's ability to survive and reproduce in a specific environment.

• Examples: Camouflage in animals, drought-resistant plants.

Biogeography

• Support for evolution: Distribution of species across different geographical areas reveals patterns that support common ancestry and adaptive evolution.

Structures and Evolution

• Homologous structures: Indicate common ancestry; similar structures adapted for different functions (e.g., human arm and bat wing).

• Analogous structures: Show similar functions but do not share a common ancestry (e.g., wings of birds and insects).

• Vestigial structures: Remnants of structures that had a function in ancestors; their presence supports evolutionary history (e.g., human appendix).

Mechanisms of Evolution

• Why traits change over time: Natural selection, mutations, genetic drift, and gene flow cause changes in trait frequencies.

• Fitness: Refers to an organism's ability to survive and reproduce; greater fitness increases the frequency of advantageous traits.

• Role of variation: Genetic variation provides the raw material for evolution, allowing some individuals to adapt better to environmental changes.

Evidence of Common Ancestry

• Shared traits: Homologous structures, embryological similarities, and genetic evidence indicate shared ancestry.

• Whale evolution: Fossil evidence and molecular biology show that whales evolved from land mammals, with intermediate forms like Ambulocetus.

Darwin’s Finches

• Beak shape changes: Variations in food sources led to natural selection favoring different beak shapes.

• Galápagos vs. mainland ancestors: Isolation and different environmental pressures caused divergence.

Speciation

• Definition: Formation of new species through evolutionary processes.

• Types:

  • Allopatric speciation: Caused by geographical barriers (e.g., mountains, rivers).

  • Sympatric speciation: Occurs without physical barriers, often through ecological or behavioral isolation.

• Required factors: Reproductive isolation, genetic divergence, and selective pressures.

Reproductive Isolation

• Prezygotic barriers: Prevent mating or fertilization (e.g., behavioral, temporal, or mechanical isolation).

• Postzygotic barriers: Prevent viable or fertile offspring (e.g., hybrid inviability or infertility).

Evolutionary Processes

• Gene duplication: Creates genetic material for potential new functions, driving evolutionary innovation.

• Selective pressure: Environmental factors that favor certain traits, leading to adaptations.

• Resistance in bacteria/insects: Mutations and natural selection lead to resistance against antibiotics or pesticides.

Biochemistry and Molecular Evidence

• Support for evolution: Similarities in DNA, RNA, and proteins across species indicate shared ancestry.

• Examples: Cytochrome c protein comparisons, genetic code universality.

Traits and Evolution

• Frequency increases: Favorable traits become more common due to higher survival and reproduction rates.

• Reproductive advantage: Traits that provide a survival or reproductive edge increase in frequency.

Key Terms to Know

• Selective pressure: Factors that influence survival and reproduction (e.g., predators, climate).

• Variation: Differences among individuals in a population, crucial for natural selection.

• Speciation: The formation of new species through evolutionary processes.