Introduction to Evolution

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Introduction to Evolution
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What is Evolution?

• In biology, evolution is the change in the
  inherited traits (a.k.a. genes/alleles,
  genotypes/phenotypes) of species (or populations
  of a species) over time.
• Throughout this unit, you will see that three
  main processes determine the rate of evolution
• 1) variation within a species (i.e. the fact that
  no one is an identical clone to another person)
• 2) reproduction the method of reproduction and
  the rate at which a species reproduces will
  affect how fast it evolves.
• 3) selection whether natural selection or sexual
  selection, you will see that those best suited to
  their particular environment will pass on their
  genes more frequently.

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Evolution by Natural Selection

• The most famous explanation of evolution was made
  by Charles Darwin, who stated that those
  organisms best suited to their environment will
  be more successful at passing on their traits to
  the next generation.
• This he called Evolution by Natural Selection.

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Darwins Influences

• Charles Darwin did not foresee himself getting
  into the field of evolutionary biology.
• He wanted to be a doctor like his father, but he
  could not stand the sight of blood and the
  savagery of surgery.
• He then wanted to be a minister, but he did not
  want to study. He preferred riding and shooting
  to studying.
• He eventually became interested in biology
  through his fascination with such exciting
  animals as barnacles, beetles and pigeons.

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Darwins Influences

• He changed his path at college and took more
  biology courses as he developed a great love of
  taxonomy (yes, the classification stuff we did in
  the first unit) and studied intensely under the
  tutelage of botany professor John Stevens
  Henslow.
• Henslow recommended Darwin for work as an unpaid
  naturalist on a voyage around the world upon the
  HMS Beagle, under captain Robert Fitzroy.
• As you will see, this journey not only changed
  Darwins life, but also the face of biology
  forever

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Adaptation and Variation

• Organisms face constant environmental challenges
  that limit their ability to survive
• Weather
• Famine
• Competition (food, space and mating)
• Organisms must survive long enough to pass along
  to offspring the genetic information that helped
  them survive
• If not, species will eventually become extinct
• Species do not choose to adapt, They either
  adapt or die!

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Adaptation and Survival

• Adaptation is a structure, behavior, or
  physiological process that helps an organism
  survive and reproduce in an environment
• Camouflage
• hibernation

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Camouflage
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Mimicry
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Mimicry A type of Structural Adaptation

• A harmless species resembles a harmful species in
  coloration or structure
• Viceroy mimics Monarch. Monarch is toxic, Viceroy
  is not, birds avoid both

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Development of Adaptations

• Result of gradual accumulative changes that help
  an organism survive and reproduce
• Random heritable mutations in DNA
• Variations are structural, functional differences
  between individuals of the same species
• Not all variations become adaptations

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Peppered Moth Variation to Adaptation
Pre Industrial Revolution
After Industrial Revolution
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The English Peppered Moth

• http//www.youtube.com/watch?vLyRA807djLc

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In Class Work

• Pg 299, Q 1-6

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Variation Within Species

• Why is there so much variation
• Amongst members of human species?
• Genetic variation in a population results from
  the variety of genetic information in all
  individuals of the population

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Mutations lead to genetic variation

• Mutations are a permanent change in the genetic
  material
• Provide new alleles in a species and source of
  new genetic variation when inherited
• Can occur spontaneously or through mutagens (UV,
  cigarettes, X-rays)
• Most mutations are benign or harmful

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Mutations in gamete cells

• If a mutation occurs in a somatic cell, it
  disappears from the population when the organism
  dies.
• If mutation is in gametes, can be passed to
  future generations as a new allele

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Mutations can provide a selective advantage

• If a mutation is beneficial it becomes a
  selective advantage improves an organisms chance
  of survival
• Individuals living in malaria-plagued regions
  have a selective advantage of what
  genotype?__________

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Rapid reproduction and selective advantage

• Some bacteria can double their population in
  under 10 minutes!
• Rapid reproduction means that an allele that was
  insignificant in the population may provide a
  selective advantage when the environment changes
• http//www.youtube.com/watch?vUxHacm6gA0c

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Antibiotic Resistance

• Activity 7.2, pg 302
• Thoughtlab pg 312 (Due Wed May 2) all the
  questions up to extend further