Evolution

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Evolution

• Chapter 16.1, 16.2, and 16.3

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Overall Theme of Evolution

• Evolution Requires 3 elements
• 1. Variety
• 2. Selection
• 3. Time

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Variety

• For evolution to occur, there must be ways for
  organisms within a species to be different from
  each other
• Variety is generated through mutations and sexual
  reproduction

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Evolution is now considered a Theory

• What is the difference between a Theory and a
  Hypothesis?
• Theory- a hypothesis that has been confirmed by
  testing and has much evidence backing it up
• Hypothesis- an educated guess that can be tested

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Charles Darwin

• Charles Darwin took many years to publish his
  theory of evolution by natural selection.
• Many of his ideas were first inspired by his 1831
  global voyage on the ship called the Beagle.

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Charles Darwin (1809 1882)

• In l831, when Darwin was only 22 he signed on as
  the ships naturalist aboard the Beagle on a
  5-year expedition around the world.
• Darwin studied and collected many different and
  unusual specimens which contributed to his
  theory.

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Darwins Voyage to the Galapagos Islands

• Some of Darwins most important observations were
  made on the Galapagos Islands.

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Animals of the Galapagos Islands
                                                
                   Blue Footed Boobies in the
Galapagos
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Galapagos Islands Finches

• Darwin observed organisms with slight
  differences.
• Example Galápagosfinches withdifferent beaks

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Assumptions At That Time

• Species were fixed creations that never changed
  and they were arranged from least complex to most
  complex.
• Earth is only a few thousand years old.

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Darwins Book On the Origin of Species

• Darwins book stated
• Species change
• Species evolved from a common ancestor over time
  (implying a much older Earth)
• Natural Selection is the mechanism for change

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The only picture in Darwins book shows Common
Ancestry
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Who influenced Darwins Ideas?

1. Jean Baptiste Lamarck (Biology)
2. Thomas Malthus (Economics)
3. Charles Lyell (Geology)

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Jean Baptiste Lamarck

• Lamarck proposed that organisms change over time
  as they adapt to changing environments.

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Jean Baptiste Lamarck

• He also incorrectly proposed that changes due to
  use and disuse of a characteristic would be
  passed on to offspring.
• Example A baseball players children would
  inherit strong arm muscles
• Giraffes neck stretches
• to reach food

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Charles Lyell

• Lyell studied fossils and rock layers
• His work showed that Earths history was long
  enough for species to have evolved gradually.

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Charles Lyell

• Lyell found evidence of long extinct habitats
• Example Fossil sea shells in the Andes Mountains

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Thomas Malthus

• Malthus observed that human populations were
  increasing faster than the food supply.
• Darwin saw that all kinds of organisms tend to
  produce more offspring than can survive.

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Darwins Theory of Natural Selection

• Overproduction- Organisms produce more offspring
  than can survive. Leads to competition for
  resources.
• Variety- Variation exists within every
  population.
• Selection- Having a particular trait can make
  individuals more or less likely to survive and
  reproduce offspring
• 4) Adaptation Over time, the traits that
  improve survival and reproduction become more
  common.

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Artificial Selection

• A human practice of breeding animals or plants
  that have desired traits
• Example Pigeon and Dog breeders

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Artificial Selection
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Evidence for Evolutionary Theory

1. Galapagos Finches
2. Transitional Fossils
3. Biogeography
4. Embryology
5. Homologous Structures
6. Biochemistry

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Galapagos Finches

• All Galapagos finch species are similar to each
  other.
• Beak size and shape are different due to
  different types of food.

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Transitional Fossils

• Traces of organisms that lived in the past.
• Some fossils show a pattern of gradual change
  from the past to the present

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Transitional Fossils
Tiktaalik roseae (Amphibian/Fish) Fossils dated
375 million years old
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Transitional Fossils
Archaeopteryx lithographica (Bird/Reptile) Fossil
s dated 150 million years old
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Transitional Fossils
Ambulocetus natans Fossils dated 50 million
years old
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Transitional Fossils
Rodhocetus kasrani Fossils dated 46 million
years old
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Transitional Fossils
Basillosaurus cetoides Fossils dated 40
million years old
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Transitional Fossils
Physeter macrocephalus Modern sperm whale
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Fossils Common Ancestry

• Darwin found fossils of Giant extinct Armadillos
  in South America that are related to Modern day
  Armadillos.

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Biogeography

• Study of the locations of organisms around the
  world.
• Example The Rhea, Ostrich, and Emu are similar
  in size, shape, eating habits, and habitat.
  However each species lives on a separate
  continent. (Convergent Evolution)

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Biogeography

• Rhea (South America)
• Ostrich (Africa)
• Emu (Australia)

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Embryology

• Study of the first stage of development

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Homologous Structures

• Characteristics that are similar in structure but
  different in function
• Homo Same
• Same evolutionary history

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Homologous Structures
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Biochemistry

• Comparison of DNA or amino acid sequences over
  time
• Most powerful evidence for a common ancestor

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Biochemistry
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Common Cell Processes

• Cellular Respiration pathways are similar
  processes in most species
• Mitosis process is the same in all eukaryotes

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Vestigial Structures

• Structures that have lost all or most of their
  original function in a species through evolution

• Examples Mole rat eyes, Manatee fingers, Human
  wisdom teeth, Wale leg bone, Human Appendix

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Vestigial Structures
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Adaptations

• An inherited trait that is present in a
  population because the trait helps individuals
  survive and reproduce in their environment.

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Adaptations

• Inuit people, who live in the extreme cold of the
  Arctic, have short, stout bodies that conserve
  heat.

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Adaptations

• Masai people, who live in the arid lands of
  eastern Africa, have tall, lean bodies that
  disperse heat well.

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Adaptations

• Venus Fly Trap
• Lives in poor soil and acquires nutrients from
  insects

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Adaptations

• Succulents have thick leaves that store water to
  prevent drying out

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Adaptations

• Camouflage- blend in with the environment

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Adaptations
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Adaptations

• Mimicry- mimics or copies characteristics of
  others

• Fly vs Honey Bee Moth
  vs Lichen

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Adaptations

• King snake vs coral snake Moth Eye
  Spot vs Owl Eyes

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Does Natural Selection Occur Now?

• Yes, Bacteria reproduce very quickly
• Over decades of antibiotic use, bacteria have
  developed resistance to antibiotic medicines
• Mutations for antibiotic resistance arise
  naturally and often in bacteria

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Antibiotic Resistance

• Today, nearly all bacteria are becoming resistant
  to one or more antibiotics
• As bacteria become resistant, physicians must
  switch to using different antibiotics.
• Example Staph infections and Tuberculosis are
  both more difficult to treat

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Misconceptions of Evolution

• Evolution does not just add complexity, it can
  take it away as well
• Example A Tapeworm lacks many organ systems

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Misconceptions of Evolution

• Evolution does not finish with a perfect
  trait
• The human eye has a blind spot due to the Optic
  Nerve

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Evolution Can Add Complexity

• Random mutation can lead to more complex changes
• Example The icefish is able to withstand the
  Antarctic freeze because it has an antifreeze
  protein in its blood that was mutated from the
  typsinogen protein.

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2 Subgroups of Evolution

• Microevolution- refers to evolution as a change
  in allele frequency in populations
• Macroevolution- refers to the appearance of a new
  species over time

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Divergent ConvergentEvolution Evolution

• See Page 383, Figure 8

new organisms
some similarities begin to develop in same
environment
common ancestor
different ancestries
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Adaptive Radiation or Divergent Evolution
A special case of divergent evolution - when
many niches are available
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Gradualism vs. Punctuated Equilibrium
Slow, even change
Long periods of no change with bursts of rapid
change
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Coevolution

• Populations are not isolated, and often evolve in
  response to each other
• Coevolution is when 2 species are competing to
  one up each other with adaptations

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Coevolution

• This moth species and this orchid species have
  coevolved is a close relationship. The moth
  feeds exclusively on the orchid, and the orchids
  pollen is spread by the moth.