Evolution
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Evolution. A Change in a species over time. Fossil Evidence. Fossils show that organisms are different today than they were in the past. What fossils show. More complex organisms came from simpler ones The older the fossil the simpler the organism. Homologous structures.

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Evolution

Evolution

A Change in a species over time


Fossil evidence
Fossil Evidence

  • Fossils show that organisms are different today than they were in the past


What fossils show
What fossils show

  • More complex organisms came from simpler ones

  • The older the fossil the simpler the organism


Homologous structures
Homologous structures

  • Same basic structure in different species

  • Human arm and Whale fin


Vestigial structures
Vestigial structures

  • No apparent function or purpose – left over from an earlier time

  • Human tail bone – no purpose now, once a tail


Embryos as evidence
Embryos as evidence

  • Many animals look the same as embryos showing all descended from a common ancestor

  • Chimps are the most closely related to humans

  • 99% same DNA


Charles darwin
Charles Darwin

  • Evolution through Natural Selection


Variations and mutations
Variations and mutations

  • Organisms in the same species have variations

  • Mutations happen within a species most are bad


Evolution through natural selection
Evolution through natural selection

  • The fittest or best suited to the environment will survive to pass their traits on to their offspring

  • Short necked giraffes – long necked giraffes

  • The long necked were better suited to the environment and survived and passed the long neck gene to future generations



Adaptations
adaptations

  • Come from variations and beneficial mutations

  • (Thumbs were a mutation)

  • Some mutations are harmful, those organisms will not survive and that trail will not be passed on to the offspring

    variations and mutations that are beneficial to surviving allow the organism to pass the trait to their offspring


Divergent evolution
Divergent evolution

  • When one species becomes two different species

  • A species gets separated due to earthquake or forest fire or some natural event.

  • Gene pools is closed to only those individuals and over time they develop through differently through variations



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