The History of Evolution
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The History of Evolution. Darwin. Lamarck. Cuvier. lion. Species. Species : group of organisms that can interbreed and produce fertile offspring Different species rarely breed Interspecies breeding often results in sterile offspring Ex: Horse x Donkey = Mule Ex: Lion x Tiger = Liger

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Lamarck

The History of Evolution

Darwin

Lamarck

Cuvier


Species

lion

Species

  • Species: group of organisms that can interbreed and produce fertile offspring

    • Different species rarely breed

    • Interspecies breeding often results in sterile offspring

      • Ex: Horse x Donkey = Mule

      • Ex: Lion x Tiger = Liger

    • New species = when unable to successfully reproduce

      • Are horses & donkeys a different species even though they can produce offspring?

tiger

liger


Lamarck

horse

donkey

mule


Lamarck

Jean Baptiste

de Lamarck

  • Acquired Inheritance: Early theory where organisms could acquire and pass traits after birth

  • Cause: environmental changes forced individuals to change

  • Problem: Traits acquired after fertilization cannot be passed to offspring

  • Early Belief: Giraffes & Long Necks

    • Long necks are result of stretching to reach leaves

    • Extra length was passed on to offspring


Geologic change

Geologic Change

  • Early belief:

    • Earth ~6,000 years old

    • Life remained unchanged

  • “New” Observations

    • Rock layers (strata) contained differing fossils

    • Deeper fossils (older) less complex

    • Environmental changes thought to affect life characteristics

    • Uniformitarianism: geologic processes that shape earth are uniform


Charles darwin

Charles Darwin

  • Observed:

    • Organisms have variations based upon environment

    • Similarities between extinct fossils & modern life

    • Marine fossils atop mountains

  • Natural Selection: Process where organisms with favorable traits survive and reproduce

  • Major concept in biology published in The Origin of Species (1859)


Adaptation variation

Variation: Inherited traits that make an individual different from others

Green, flat wings of the insect above

Adaptation: Variation increases the chance of survival

Ability to blend with environment

Adaptation & Variation


Lamarck

Butterflies won't

lay eggs on plants

with fake egg spots


Lamarck

Can you find

the geckos?


Lamarck

Gross....bird poop...or is it???


Causes of genetic variation

Causes of Genetic Variation

  • Genetic variation increases chances some survive changing environments

  • Gene Pool: All alleles within a population

  • Two main causes of genetic variation:

    1) Mutations: Random genetic changes may affect phenotypes

    2) Recombination: During meiosis, genes recombine in varying patterns


Variation 4 different gametes

Variation: 4 Different Gametes

Chromatids

copied

Crossing-

over

Crossing-

Over

finished

Genetic variation!

Four differing chromatids


Lamarck

Quick Review

  • Features of a species can evolve, or change over time

  • Natural selection is when favorable traits allow survival & reproduction

  • Variations allow an organism to be better suited to its environment


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