Principles of Evolution Flash Cards

Evolution

• Definition: Evolution is the change in the heritable characteristics of biological populations over successive generations.

Scientific Theory of Evolution

• True/False: False. The scientific Theory of Evolution does not explain how life began; it explains how life has changed over time.

Definition of Scientific Theory

• A scientific theory is a well-substantiated explanation of an aspect of the natural world that is based on a body of evidence and has been repeatedly tested and confirmed.

Claims of Jean-Baptiste Lamarck (1809)

• Lamarck proposed that organisms evolve through the inheritance of acquired characteristics, suggesting that traits acquired during an organism's lifetime can be passed on to its offspring.

Earth’s Age in the Early 1800s

• The common view in the early 1800’s was that the Earth was young and unchanging.

  • Challenger: Charles Lyell challenged this idea.

  • Uniformitarianism: A principle that states that the Earth has changed gradually over time due to the same processes that are observable today.

  • Current estimation: Today’s scientists theorize the Earth is actually around 4.5 billion years old.

Observations from Darwin on the HMS Beagle

• Darwin made observations of diverse species, geographic distribution, fossils, and geological formations during his 5-year journey.

Evidence for an Ancient, Changing Earth

• Darwin observed geological features and fossil records that indicated gradual changes over time, supporting the notion of an ancient, changing Earth.

Observations on the Galapagos Islands

• Key observations made by Darwin include:

  • A wide range of variations among living things.

  • Interspecies Variations: Differences among species (e.g., finches on different islands).

  • Intraspecies Variations: Differences within a species (e.g., different beak shapes among finches).

Adaptation

• Definition: An adaptation is a trait that enhances an organism's ability to survive and reproduce in its environment.

• Example: Darwin observed variations in tortoise neck lengths on different islands that helped them access food sources.

  • Conclusion: Adaptations seen in populations must be a result of natural selection.

Influence of Artificial Selection

• Darwin’s knowledge of artificial selection influenced his thinking by illustrating how selective breeding could produce significant changes in traits over generations.

Natural Selection

11. Darwin concluded that adaptations occur through natural selection over many generations.

• Nature “selects” who survives because…

  • a. Organisms with the best survival traits are more likely to survive.

  • b. If an organism survives, it is more likely to reproduce.

  • c. These beneficial traits are passed on and accumulated over generations.

Darwin's Publication

12. The name of the book published by Charles Darwin is On the Origin of Species.

Survival of the Fittest

13. “Survival of the Fittest” reflects the concept of natural selection where organisms best adapted to their environment are more likely to survive and reproduce.

• Definition of Fitness: Fitness refers to an organism's ability to survive and reproduce in a given environment.

Comparing Lamarck vs Darwin

14. Lamarck's Claims: Proposed that giraffes grew longer necks because they needed to reach high food; these traits would be passed on. Darwin's Claims: Proposed that giraffes with longer necks had a survival advantage, leading to increased reproduction of that trait over generations.

Principles of Natural Selection

15. The four principles are:

• Variation: Individual differences in traits in a population.

• Overproduction: More offspring are produced than can survive.

• Adaptation: Traits that improve survival and reproduction become more common.

• Descent with Modification: Offspring inherit traits but often with variations, leading to changes over time.

Darwin's Observations of the Galapagos Finches

16. Observations included:

• a. Variations in beak size and shape corresponding to food sources.

• b. The work of ecologists Peter and Rosemary Grant supported Darwin's conclusions by demonstrating documented changes in beak size in response to environmental changes.