Evolution

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Evolution

• Introduction

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Evolutions Importance

• Nothing in Biology makes sense except in the
  light of Evolution
• Theodosius Dobzhansky (1973)

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The Question

• Where did all the species we see today come
  from?
• The Early Answer
• All species are fixed and were placed on Earth
  by an intelligent Creator

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Plato Aristotle
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The Evolution Revolution

• Evolutionary Theory did not come into being until
  the mid 19th century.
• There were a number of scientists who contributed
  to the development of Evolutionary Theory, but
  the father of Modern Evolution is considered to
  be

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Charles Darwin
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or
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Question?

• How do we go from here
• To here?

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Answer Evolution

• Evolution change over time
• But how? Darwins Theory of Evolution

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Darwin

• Charles Darwin was a naturalist who traveled
  around the world on the HMS Beagle. One of the
  most important stops of the ship (for science)
  was the Galapagos Islands

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Darwins Finches

• Darwin collected many different plant and animal
  species on the island, but the most important
  were a type of bird, the finch.
• At first Darwin thought that his finches were all
  the same species with different beaks, but soon
  realized that they were actually all different
  species of finch!!!

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Question?

• Why would there be so many different species of
  finch on the islands?
• Answer Environment
• Each island of the Galapagos has a somewhat
  different climate, therefore different food
  sources.

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Examples

• On one island, there may have been large numbers
  of small insects Beak type ?long, narrow,
  pointed
• On another island the main food source could have
  been large thick seeds Beak type ? short, thick

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Darwin Needed Help

• Carolus Linnaeus (1707-1778)

Homo sapiens
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Darwin Needed Help

• Georges Cuvier (1762-1832)

Paleontologist
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Darwin Needed Help

• James Hutton (1726-1797)

Geologist
GRADUALISM
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Darwin Needed Help

• Charles Lyell (1795-1875)

Uniformitarianism
Geologist
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Darwin Needed Help

• Jean Baptiste Lamarck (1744-1829)
• 3 ideas
• 1. Use and Disuse
• 2. Inheritance
• 3. Adaptation

Wrong
Kind of
Correct
Naturalist
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Darwins Theory of Evolution

• Individual organisms in nature differ from one
  another, some of that variation is inherited.
• Organisms produce more offspring than can
  survive, any many of those who survive do not
  reproduce.
• Because more species are produced than can
  survive, members of each species must compete for
  resources.

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Darwins Theory of Evolution

• Because each organism is unique, each has
  different advantages/disadvantages in the
  struggle for existence.
• Individuals best suited to their environment
  survive and reproduce most successfully. The
  characteristics that make them best suited to
  their environment are passed on to their
  offspring.
• Over long periods of time, species changeor go
  extinct. New species arise as well.

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Variation

• Variation must be found in a species in order for
  evolution to take place.
• Types of Variation
• Mutation changes in DNA of an organism that
  (could) lead to physical changes
• Genetic shuffling mixing of genes that occurs
  when sperm and egg combine to form the zygote

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Adaptation

• Inherited characteristics that enhance an
  organisms ability to survive and reproduce in a
  particular environment.

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Natural Selection

• Nature (the environment) chooses which organisms
  are best fit to survive and reproduce.
• Survival of the fittest.

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Darwins 4 Postulates
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Darwins Theory

• Darwins Theory of Evolution can be summarized
  (and slightly simplified) into 4 postulates.
• We will stick with rabbits as our application of
  his postulates.

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1

• Living things overproduce.

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2

• There is variation among offspring
• Mutation (random changes in DNA)
• Sorting of male/female genes during sexual
• reproduction
• Ex. Diff fur colors
• (dark, light)

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3

• There is a struggle to survive
• Odds are stacked against baby rabbit
• Predation
• Disease
• Competition (for resources, shelter, etc)
• Environment (temp, weather, rainfall, etc)

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4

• Natural Selection is always taking place
• Individuals w/ more desirable traits are more
• fitmore likely to reproduce and pass
  trait
• on to offspring
• Rabbits with white fur are more fit in a snowy
  environment.
• Black fur ? selected against

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Adaptation

• Definition an inherited characteristic that
  increases an organisms chance of survival
• Can be physical, or more complex (like
• behavior)