Ch. 23.2 Evolutionary Changes

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Ch. 23.2 Evolutionary Changes

  1. 1. Ch. 23: Evolution<br />Evolutionary Changes<br />
  2. 2. Types<br />Fossil Record<br />Biogeography<br />Convergent Evolution<br />Selective Breeding<br />Homologies<br />Anatomical<br />Developmental<br />Molecular<br />
  3. 3. Fossil Record<br />Shows timeline of successive evolutionary change<br />Transitional fossils<br />Intermediate states<br />Exhibit characteristics of ancestors as well as descendants<br />
  4. 4.
  5. 5. Biogeography<br />Geographic distribution of species<br />Extinct and living<br />Reveal patterns of evolution<br />Endemic Species<br />Found only in a particular location<br />Isolated<br />
  6. 6. Convergent Evolution<br />Organisms with similar characteristics that are not evolutionarily related<br />Similar environments with similar adaptive pressures.<br />Suggests adaptation as an evolutionary force<br />Similar features are termed analogous structures (convergent traits)<br />
  7. 7. Selective Breeding<br />Human Controlled<br />Called “artificial selection”<br />Human breeders determine reproduction<br />Surviving traits are human-desired<br />Augmentation of already present genetic variation<br />
  8. 8. Homologies<br />Similar traits between two species<br />Descent from a common ancestor<br />Featured observed<br />Anatomical Homologies<br />Developmental Homologies<br />Molecular Homologies<br />
  9. 9. Anatomical Homologies<br />Observations of anatomical structures between species<br />Similar patterns exhibited within features<br />Homologous Structures<br />Same traits may be modified for different functions in successive species<br />
  10. 10. Vestigial Structures<br />Structures resembling those of a species’ ancestors but lacking a function in the species itself.<br />Evolutionary relics<br />Structures were functional in ancestral species, but lost function as the species changed lifestyle<br />Structure does not disappear but is degenerated by mutations<br />
  11. 11. Developmental Homologies<br />Species that appear very differently as adults can bear striking similarities in the embryonic stage<br />Similarities are temporary and are lost during development.<br />Traits indicate evolutionary ancestors<br />
  12. 12. Molecular Homologies<br />Observations of features at the molecular level<br />All organisms use DNA as genetic material<br />RNA carries information for proteins as functional products<br />Certain biochemical pathways are universal<br />These features arose very early in the history of life<br />Analysis of genetic sequences reveals evolutionary relatedness<br />Closest relatives have higher percentage of identical sequences<br />

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