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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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Presentation Transcript
slide1

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

slide3

horse

donkey

mule

slide4

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
slide8

Butterflies won\'t

lay eggs on plants

with fake egg spots

slide9

Can you find

the geckos?

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

slide13

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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