Evolution

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Evolution

• All species living today emerged from nonliving
  matter about 4.6 billion years ago, and have
  continued to change to the present day.
• http//www.youtube.com/watch?vfaRlFsYmkeY

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Microevolution

• Small genetic changes within a population

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How Does Mutation Play A Role?
Genetic variability originates through genetic
mutation RANDOM changes in DNA
Exposure to Mutagens x rays radioactivity
Random mistakes occurring during DNA replication
Mutations are 1) unpredictable 2) only
source of new genetic material 3) rare -
rarely beneficial
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Natural Selection
Charles Darwin
Genetically based traits in organisms increases
their chance of survival an therefore their
ability to produce offspring.
On the Origin of Species by Means of Natural
Selection - 1859
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Natural selection is the simple result of
variation, differential reproduction, and
heredity it is mindless and mechanistic. It has
no goals it's not striving to produce "progress"
or a balanced ecosystem.
How Works!
Not How It Works!
http//evolution.berkeley.edu
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The Peppered Moths
Industrial Melanism
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Directional Selection

• Phenotypes shift in a certain direction, usually
  in response to an environmental change.

• Resistance to antibiotics and pesticides.
• Finch beaks.
• Peppered moths?

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Disruptive or Diversifying Natural Selection

• Environment favors individuals with uncommon
  phenotypes

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Sexual Selection

• Traits are favored because they are attractive to
  mates, which gives the organism a greater chance
  to reproduce and have more offspring.
• Males are often more aggressive and/or colorful.
  Remember FLASHY GUPPIES?

FITNESS
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Gene Flow

• Movement of alleles (bits of heritable material
  responsible for certain traits) into and out of a
  population due to immigration (in) and emigration
  (out).
• Ex. Seed dispersal, migration.
• Can minimize the differences between local
  populations.

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Genetic Drift

• Random/chance changes in abundance of certain
  varieties in a population. (allele frequency)
• Genetic drift simulation
• Reduces variety in the population.
• Small, isolated populations are most affected.

Lucky genes may survive in the environment
http//evolution.berkeley.edu
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Bottleneck Effect

• Population size decreases drastically as a result
  of disease, intense predation/hunting, natural
  disasters, etc.
• Subsequent inbreeding decreases immunity
  (higher chance of death by disease or genetic
  disorders)

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Founder Effect

• A form of bottlenecking caused by dispersal.
• Long-distance migration, wind, ocean currents,
  mechanical transport, etc.

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Coevolution

• Interactions between species initiate
  microevolution events.
• When populations of two different species
  interact over a long time, changes in the gene
  pool of one species can lead to changes in the
  gene pool of the other species.

Example Rough Skinned Newt Garter Snake
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Macroevolution

• Speciation
• http//www.youtube.com/watch?vxkwRTIKXaxg

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Speciation

• The formation of two species from a common
  ancestor.

http//evolution.berkeley.edu
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Allopatric Speciation (Geographic Isolation)
How does speciation occur?
Geographic Isolation

• A group of a species becomes separated from one
  another, cutting off or severely restricting gene
  flow. Over time, through microevolution, the
  groups become different enough that they cannot
  interbreed.

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Resource availability generally limits
population size
Potential for rapid population growth when
resources are not limiting
Competition for resources (struggle for
existence)
Phenotypic variability (morphology, physiology,
behavior, etc.)
Natural Selection Survival and reproduction of
the fittest individuals
Some variabilityresults from heritable
genotypic differences
Adaptive evolution A change in the phenotypic
constitution of a population owing to selection
on heritable variation among phenotypes that
changes the genotypic constitution of the
population
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Adaptive Radiation
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Divergent evolution produces homologous
characters.
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Convergent evolution may produce analogous
characters.
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Vestigial Structures
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Gradualism vs. Punctuated Equilibrium
RATES OF EVOLUTION Gradualism gradual change
over a long period of time Punctuated Equilibrium
periods of rapid change are separated by
periods of little or no change
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Fern fossil
How Do We Know?
Fossil Record
The Burgess Shale Middle Cabrian age (about 540
million years ago) .Yoho National Park (in the
Rocky Mountains)British Columbia, Canada. The
locality is special because of the soft-bodied
preservation of a wide diversity of fossil
invertebrate animals.
Cyanobacteria
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The fossil record clearly shows changes in life
through almost any sequence of sedimentary rock
layers. Successive rock layers contain different
groups or assemblages of fossil species.
Sedimentary rocks - most common rocks on Earths.
Form from older rocks broken down by erosion.
Gravel, sand, and mud, (sediment), settle in
layers on bottoms of rivers, lakes, and oceans.
Sediments bury shells, bones, and other pieces of
living things. Over time, the layers of sediments
are compacted by the weight of overlying
sediments and cemented together to become the
sedimentary rocks called limestone, shale,
sandstone, and conglomerate. The buried plant and
animal remains become fossils within the
sedimentary layers.
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• Using radiometric dating scientists determine the
  of the original atoms of specific isotopes
  remaining to deduce approximate age. (half-life
  methods)
• Techniques have improved to 99 accuracy

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• Documentation of ancestor-descendant
  relationships among organisms also comes from the
  fields of biogeography, taxonomy, anatomy,
  embryology and, most recently, genetics
  particularly DNA analysis. www.agiweb.org

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Fundamental Niche

• The fundamental niche is the full potential range
  of conditions and resources a species could
  potentially use.
• Its realized niche is the part of the potential
  niche that allows a species to survive and avoid
  competition with other species for the same
  resources

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Broad and Narrow Niches and Limits of Adaptation

• Generalist species
• Specialist species
• Limits of adaptation

Refer to Spotlight, p. 69
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Generalist Species

• Some species have broad ecological roles and are
  termed generalist species.
• 1. Their living range is broad, includes many
  different places.
• 2. They can eat a variety of foods, and tolerate
  a wide range of environments.
• 3. If environment is changeable, the generalist
  will survive better than the specialist
  http//www.youtube.com/watch?v9CuhqQzBACQ
• http//www.youtube.com/watch?v2L82V6VPJkQfeature
  watch_response

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Future of Evolution

• Artificial selection
• Genetic engineering (gene splicing)
• Genetic modified organisms (GMOs)
• http//www.youtube.com/watch?vijrtROGpqJ8
• Cloning
• Ethical concerns

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What is genetic engineering?

• Genetic engineering, also known as recombinant
  DNA technology, means altering the genes in a
  living organism to produce a Genetically Modified
  Organism (GMO) with a new genotype.
• Various kinds of genetic modification are
  possible inserting a foreign gene from one
  species into another, forming a transgenic
  organism altering an existing gene so that its
  product is changed or changing gene expression
  so that it is translated more often or not at
  all.

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What is a GMO crop?

• Transfer of a gene from a soil bacteria that
  codes for a protein
• Protein becomes a toxin and kills selected
  insects

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Why would we want to modify an organism?

• Better crop yield, especially under harsh
  conditions
• Herbicide or disease resistance
• Nutrition or pharmaceuticals, vaccine delivery
• In 2004, approximately 85 of soy and 45 of
  corn grown in the U.S. were grown from Roundup
  Ready seed.

http//www.oercommons.org/courses/detecting-geneti
cally-modified-food-by-pcr/
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Basic steps in genetic engineering

• Isolate the gene
• Insert it in a host using a vector
• Produce as many copies of the host as possible
• Separate and purify the product of the gene

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Genetic Engineering
Phase 1 Make Modified Gene
E. coli
Cell
Genetically modified plasmid
Extract plasmid
Extract DNA
plasmid
DNA
Gene of interest
Identify and extract gene with desired trait
Identify and remove portion of DNA with desired
trait
Remove plasmid from DNA of E. coli
Insert extracted DNA (step 2) into plasmid (step3)
Insert modified plasmid into E. coli
Grow in tissue culture to make copies
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Genetic Engineering
Phase 2 Make Transgenic Cell
A. tumefaciens (agrobacterium)
Foreign DNA
E. coli
Host DNA
Nucleus
Transfer plasmid copies to a carrier agrobacterium
Agrobacterium inserts foreign DNA into plant cell
to yield transgenic cell
Transfer plasmid to surface microscopic
metal particle
Use gene gun to inject DNA into plant cell
Fig. 4-11, p. 75
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Genetic Engineering
Phase 3 Grow Genetically Engineered Plant
Transgenic cell from Phase 2
Cell division of transgenic cells
Culture cells to form plantlets
Transfer to soil
Transgenic plants with new traits
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Evolution Misconceptions

• Survival of the fittest does NOT mean survival
  of the strongest.
• Humans did not evolve from APES
• Evolution is not a grand plan or ecosystem
  strategy