Evolution By Natural Selection Flashcards Preview

Grade 12 LS 2016 > Evolution By Natural Selection > Flashcards

Flashcards in Evolution By Natural Selection Deck (17):
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Theory

An explanation with a large amount of evidence and testing behind it.

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Definition of evolution

  • Descent with modification
  • accumulation of changes in a population over many generations

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Fossils

  • Preserved remains (e.g. Bones and teeth)
  • impressions (e.g. Footprints)
  • of organisms that lived in the past.

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A scientist who studies fossils

Palaeontologist

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The earth science that studies fossil organisms and related remains of past organisms

Palaeontology

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Any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group

Intermediate forms or transitional forms

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Method name and substance used to determine the absolute age of a fossil

  • Radiometric dating
  • Using radioactive isotopes

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Oldest fossils found by scientists

  • Microfossils of bacteria
  • Roughly 3.5 billion years old

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Some different types of evidence for evolution

  • Fossil record
  • Observed microevolution
  • Biogeography
  • DNA/gene homology
  • Embryology
  • Anatomical homology
  • Vestigial structures

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Biogeography

The study of the distribution of species and ecosystems in geographic space and through geological time.

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Biogeography as evidence for evolution

Species tend to be more closely related to other species from the same area than to other species with the same lifestyle and form but living in different areas

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Genetics or DNA/gene homology as evidence for evolution

  • Shared nucleotide sequence between more closely related species than more distantly related species
  • as evidence of shared common ancestry

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Embryology as evidence of evolution

  • The embryonic stages of animals are similar.
  • For example, fish, bird, rabbit and human embryos are all similar in appearance in early stages.
  • They all have gill slits, two chambered hearts, and a tail with muscles to move it.
  • Later as embryo's grow and develop they become less similar.
  • Essentially: embryonic homology.

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Homology

  • The existence of shared ancestry between a pair of structures, or genes, in different species.
  • A common example of homologous structures in evolutionary biology are the wings of bats and the arms of primates.
  • Evolutionary theory explains the existence of homologous structures adaptations to different environments as the result of descent with modification from a common ancestor.

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Anatomical homology as evidence for evolution

Structural similarity in more closely related species irrespective of the anatomical function.

E.g. Tetrapod limbs contain the same pattern of bones no matter the function of the limb (flying, swimming, walking etc.)

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Similar structures, sharing function, but not derived from common ancestry. Also provide an example of these structures that are not homologous.

  • Analogous structures
  • E.g. Butterfly wings and bat wings
  • E.g. Fish ray fins and a whales flippers

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