Evolutionary Theory Overview
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Questions and Answers

What is a theory in the context of evolutionary biology?

A theory is a broad explanation that is supported by evidence.

Define 'descent with modification'.

Descent with modification is the change over time in the genetic composition of a population.

What two principles did Jean Baptiste de Lamarck propose?

'Use and disuse' and 'inheritance of acquired characteristics.'

How did Charles Lyell contribute to our understanding of geological processes?

<p>Charles Lyell proposed uniformitarianism, stating that uniform natural laws govern geologic processes.</p> Signup and view all the answers

What observations did Darwin make about finches on the Galapagos Islands?

<p>Darwin observed that different finches had varying beak shapes and behaviors suited to available food sources.</p> Signup and view all the answers

Explain the term 'adaptive radiation'.

<p>Adaptive radiation is a period of evolutionary change where multiple new species evolve from a common ancestor to fill various ecological niches.</p> Signup and view all the answers

What role do fossils play in the study of evolutionary change?

<p>Fossils provide remains or traces of past organisms, offering insights into historical life and transitions.</p> Signup and view all the answers

What is paleontology?

<p>Paleontology is the study of fossils.</p> Signup and view all the answers

What significant work did Darwin publish in 1859, and what were its two main points?

<p>Darwin published 'On the Origin of Species,' which primarily discussed descent with modification and natural selection and adaptation.</p> Signup and view all the answers

What does Darwin's metaphor of a tree represent in the context of evolution?

<p>The tree metaphor represents organisms that are related through descent from a common ancestor, with multiple branches signifying diverse species.</p> Signup and view all the answers

How does artificial selection differ from natural selection?

<p>Artificial selection is the human-directed breeding of organisms for specific traits, while natural selection occurs through environmental pressures favoring the survival of the fittest individuals.</p> Signup and view all the answers

What are the two key principles of natural selection described in the content?

<p>Natural selection is characterized by the production of more offspring than can survive and that survivors possess traits suited to their environment.</p> Signup and view all the answers

Explain the role of genetic variation in the process of natural selection.

<p>Genetic variation within a population provides the diversity of traits that can be selected for or against by the environment, influencing survival and reproduction.</p> Signup and view all the answers

What is meant by the term 'evolutionary adaptation'?

<p>Evolutionary adaptation refers to the process through which populations become better suited to their environments over successive generations due to favorable heritable traits being passed on.</p> Signup and view all the answers

Can evolution occur in individuals? Justify your answer.

<p>No, evolution occurs in populations over many generations, as individual traits do not change within a lifetime.</p> Signup and view all the answers

How does the example of the soapberry bug illustrate natural selection?

<p>The soapberry bug's shorter beak length evolved in response to changes in its food source, demonstrating natural selection favoring traits better suited to its environmental conditions.</p> Signup and view all the answers

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Study Notes

Evolutionary Theory

  • A theory is a broad explanation supported by evidence
  • Evolution is descent with modification, meaning change in the genetic makeup of a population over time.
  • Evolutionary theory is both a pattern (facts observed in nature) and a process (mechanisms causing change)

The Road to Darwin

  • Aristotle (384-322 BCE) proposed Scala Naturae, a hierarchical ladder of life.
  • Carolus Linnaeus (1707-1778) developed binomial nomenclature for classifying organisms.

Ideas about change over time

  • Fossils are remains or traces of past organisms.
  • Strata are layers of rock.
  • Paleontology is the study of fossils.
  • Georges Cuvier (1769-1832) proposed catastrophism (periods of rapid change).
  • James Hutton (1726-1797) proposed gradualism, that Earth's features change gradually over long periods.
  • Charles Lyell (1797-1875) proposed uniformitarianism, that geological processes have been uniform over geological time.

Jean-Baptiste de Lamarck (1744-1829)

  • Lamarck proposed gradual evolutionary change, explaining the fossil record.
  • Organisms adapt to their environments.
  • He proposed two principles: use and disuse (characteristics acquired during an organism's lifetime can be passed down), and inheritance of acquired characteristics.
  • Lamarck was incorrect in the mechanism of transmission of acquired characteristics, but correctly identified that organisms adapt to their environments.

Darwin's Theory of Finches on the Galapagos Islands

  • Darwin observed finches with diverse beak shapes and sizes.
  • Different beaks and behaviors were suited to specific foods available on various islands.
  • This is an example of adaptive radiation.

Adaptive Radiation

  • A period of evolutionary change where groups of organisms form many new species.
  • Adaptions enable them to fill different ecological roles.

After HMS Beagle Voyage

  • Darwin wrote an essay on the origin of species and natural selection in 1844.
  • It was not published.
  • Alfred Russel Wallace also developed similar ideas.
  • Darwin and Wallace jointly presented their ideas in 1858.
  • Darwin's book "On the Origin of Species" was published in 1859.

On the Origin of Species

  • Darwin's book published in 1859.
  • Two main points: Descent with Modification and Natural Selection.

Descent with Modification

  • Darwin's phrase for evolution.
  • Organisms are related through descent from common ancestors who lived in the past.

Artificial Selection

  • Humans modify other species through selective breeding of individuals.
  • Examples include cabbage, broccoli, and kale.

Natural Selection

  • More offspring produced than can survive.
  • Those that survive are "suited" to the environment, are successful in reproduction, and pass genes to offspring.
  • Favorable adaptations stay; unfavorable adaptations are lost.
  • This results in populations, not individuals, evolving over many generations so organisms are better adapted to their environment.
  • Depends on genetic variation within populations.

Evidence for Evolution

  • Observations of evolution: Examples include beak changes in soapberry bugs.
  • Homology: Similarity in characteristics resulting from shared ancestry.
    • Homologous structures: Variations on a structural theme from a common ancestor (e.g., forelimbs of mammals).
    • Vestigial structures: Remnants of features serving a function in an ancestor (e.g., whale pelvis).
    • Molecular homologies: Similarities in DNA and protein molecules between related organisms.
  • Convergent evolution: Similar adaptations in unrelated organisms due to similar environments (e.g., sugar glider and flying squirrel).
  • Fossil record: Fossilized remains of organisms that lived in the past confirm the order organisms appeared.
  • Biogeography: Geographic distribution of species and similarities in fossils found on recently separated landmasses.

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Related Documents

Descent with Modification PDF

Description

Explore the foundational concepts of evolutionary theory, including its definition and historical context leading to Darwin. Discover how ancient ideas about life's hierarchy, fossils, and geological change have shaped our understanding of evolution over time.

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