Darwin VS. Lamarck

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Darwin VS. Lamarck

• Chapter 15-2

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Jean Baptiste de Lamarck (1744-1829)

• First to propose the theory of evolution.
• Lamarck claimed that species are descendents from
  early ancestors.
• Fossil records supported his findings.

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Lamarcks Theory

• Lamarck claimed that species changed over time
  due to an acquired trait.
• Acquired trait- A trait not determined by genes
  but acquired through a life time.
• Lamarcks theory was later proven false.

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Charles Darwin (1809-1882)

• Charles Darwin came up with a different theory to
  explain how evolution takes place.
• Darwin collected evidence for his theory on his
  journey around the world on a ship called the
  H.M.S. Beagle.

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Natural Selection

• Darwins theory was based on the idea of what he
  called natural selection.
• Natural selection- Organisms best suited to their
  environment reproduce more successfully than
  other organisms. Thus passing down their
  favorable traits to their offspring.

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Voyage of the Beagle

• One of Darwin's most famous collections from his
  trip was the collection of finches from the
  Galapagos islands.

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The Finches

• Darwin collected 13 different species of finches
  from the island.
• Each bird had a distinct bill specialized for a
  particular food source.
• Darwin later concluded that these 13 species came
  from one common ancestor.
• Darwin thought that the original ancestors had
  migrated from the nearby coast of South America.

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The Origin of Species

• Darwin later published his findings in a book
  titled the Origin of Species.

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Survival of the Fittest

• We often use the term survival of the fittest
• What does this mean?

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Survival of the Fittest

• Animals with favorable traits will survive and
  pass those genes to the offspring.
• The contribution of genes an organism gives to
  the next generation is called fitness.

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Fitness

• As more favorable genes are contributed to the
  population the organisms will change over time.
• This is Darwins idea of natural selection.
• The process by which a population becomes better
  suited to its environment is known as adaptation.

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THE FORMATION OF A NEW SPECIES

• Chapter 15-3 and 16-3 Notes

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Homologous Structure

• Homologous Structure- Similar features that are
  found in a shared ancestor.

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Vestigial Structures

• Vestigial Structure- Structures that were useful
  to ancestors now have no purpose.

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Vestigial Structures
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Vestigial Structures
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Similarities in Embryology

• The early stages of different vertebrate embryos
  are strikingly similar to each other.
• The similar appearance provides further evidence
  that species originated from a common ancestor.

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Similarities in Macromolecules

• Darwin based many of his conclusions on the
  physical similarities between organisms.
• Darwin was unable to examine similarities at a
  molecular level.
• Scientists have later studied the molecular
  similarities between different organisms.

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Molecular Similarities

• The similarity in amino acid sequence can
  determine how closely related two species are.
• And how long ago they branched off the
  evolutionary chain and developed a new species.

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Analogous Structures

• When organisms that vary greatly anatomically
  evolve similar structures that serve similar
  functions.
• Example bird wing and insect wing
• Example bird beak and giant squid beak
• Share very distant relatives.

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Co- Evolution

• The change of two or more species in close
  association with each other is called
  co-evolution.
• Example Bat and flower

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Some flowers and bees have coevolved in a way
that their existence depends on each other.
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Convergent Evolution

• Selection that causes two species to become very
  similar to each other even though they have very
  different ancestors.
• Example- Dolphin and Shark

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Convergent Evolution
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Divergent Evolution

• Two or more related populations or species become
  more and more dissimilar.
• Divergence is nearly always a response to
  differing environmental factors and can
  ultimately result in new species.
• The rate of divergent evolution among dogs has
  been increased by artificial selection in humans.

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Speciation

• Speciation- Is the formation of new species which
  results in many related populations of organisms.

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Biological Species Concept

• The Biological Species Concept states- A species
  is a population of organisms that can
  successfully interbreed but can not breed with
  other groups.

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Biological Species Concept

• The biological species concept works great for
  living organisms but is difficult for organisms
  that have since become extinct.

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Speciation

• In order for speciation to occur there must be
  isolation.
• In isolation two parts of formerly interbreeding
  populations stop interbreeding.
• Why is isolation important for speciation to
  occur?

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Speciation

• Two major types of isolation frequently drive
  speciation
• Geographic Isolation
• Reproductive Isolation

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Geographic Isolation

• Geographic Isolation- Is the physical separation
  of members of a population.
• Examples
• Canyon formation
• Shrinking ponds
• - Islands

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Reproductive Isolation

• Reproductive Isolation- Reproductive isolation
  results from barriers to successful breeding
  between population groups in the same area.

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Reproductive Isolation

• Examples
• Offspring does not survive to reproduce
• Mating call that is not recognized
• Different mating times
• Selective mate

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