Evolution and Biodiversity

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Chapter 4

• Evolution and Biodiversity

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Evolution

• Microevolution
• Change over time in genetic make up of a species
• Macroevolution (biological evolution)
• Change over time from one organism to another
• Theory of Evolution
• Macroevolution
• Natural selection

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When talking about EvolutionPlease remember

• Not everything you read about Evolution is true.

• There is a lack of evidence to support Biological
  Evolution.

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When talking about EvolutionPlease remember

• A belief in evolution undermines the Bible and
  Christianity as a whole.

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Chapter 4

• Natural Selection and Biodiversity

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Why Should We Care About Biodiversity?

• Biodiversity provides us with
• Natural Resources (food water, wood, energy, and
  medicines)
• Natural Services (air and water purification,
  soil fertility, waste disposal, pest control)
• Aesthetic pleasure

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NATURAL SELECTION AND ADAPTATION

• Natural selection involves the change in a
  populations genetic makeup through successive
  generations.
• genetic variability
• Mutations random changes in the structure or
  number of DNA molecules in a cell that can be
  inherited by offspring.

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I regard gene mutation as a very logical and
possible occurrence but I do not think that it
is, in view of the stability of the gene, as
important a factor in speciation as its
proponents contend. I would also like to
emphasize that there are other methods of
speciation such as polyploidy and
hybridizationIrving W. Knobloch, Ph.D
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"It may, in short, be stated that no mutation has
ever occurred in the progress of genetic work
which is fully viable and behaves as a dominant
to the wild-type condition. That any have given
rise to changes which could be of survival value
in nature appears highly doubtful". E. B.
Ford, Mendelism and Evolution, Dial Press, N.
Y., 193L
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"Mutation changes one gene at a time
simultaneous mutation of masses of genes is
unknown. On the other hand, species differ from
each other usually in many genes hence, a sudden
origin of a species by mutation, in one thrust,
would demand a simultaneous mutation of numerous
genes." Theodosius Dobzhansky, Genetics and the
Origin of Species, 2nd Ed., Columbia Univ.
Press, 1941
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"Although a great many species have been studied,
it must be admitted that most of them are not in
a mutating condition. Thus if mutation is not a
general phenomenon, it can have but slight
significance as a means of species formation"
Arthur W. Haupt, Fundamentals of
Biology, McGraw Hill Book Co., N. Y., 1928.
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Hybridization and Gene Swapping other Ways to
Exchange Genes

• New species arise through hybridization.
• Occurs when individuals of 2 distinct species
  crossbreed to produce a fertile offspring.
• Some species (mostly microorganisms) can exchange
  genes without sexual reproduction.
• Horizontal gene transfer

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Geographic Isolation

• can lead to reproductive isolation, divergence
  of gene pools and speciation.

Figure 4-10
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Climate Change and Natural Selection

• Changes in climate throughout the earths history
  have shifted where plants and animals can live.

Figure 4-6
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Natural Selection and Adaptation Leaving More
Offspring With Beneficial Traits

• Three conditions are necessary
• Genetic variability
• traits must be heritable
• trait must lead to differential reproduction.

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Natural Selection and Adaptation Leaving More
Offspring With Beneficial Traits

• An adaptive trait is any heritable trait that
• enables an organism to survive through natural
  selection and
• reproduce better under prevailing environmental
  conditions.

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Natural Selection A Biological Arms Race

• Interacting species can engage in a back and
  forth genetic contest in which each gains a
  temporary genetic advantage over the other.
• This often happens between predators and prey
  species.

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Limits on Adaptation through Natural Selection

• A populations ability to adapt to new
  environmental conditions through natural
  selection is limited by its gene pool and how
  fast it can reproduce.
• Humans have a relatively slow generation time
  (decades) and output ( of young) versus some
  other species.

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Common Myths about Natural Selection

• Natural selection is not about survival of the
  fittest.
• It is about the most descendants.
• Organisms do not develop certain traits because
  they need them.
• It is a completely random process.
• There is no such thing as genetic perfection.

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SPECIATION, EXTINCTION, AND BIODIVERSITY

• Endemic species
• Found in only one place
• Vulnerable to extinction
• Background extinction
• Low rate of disappearance
• Mass extinction
• Significant rise in disappearance rate

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Extinction Lights Out

• Extinction occurs when the population cannot
  adapt to changing environmental conditions.

• The golden toad of Costa Ricas Monteverde cloud
  forest has become extinct because of changes in
  climate.

Figure 4-11
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SPECIATION, EXTINCTION, AND BIODIVERSITY

• Richness
• Number of different species
• Evenness
• Relative abundance of individuals within each
  species

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ECOLOGICAL NICHES AND ADAPTATION

• Each species in an ecosystem has a specific role
  or way of life.
• Fundamental niche the full potential range of
  physical, chemical, and biological conditions and
  resources a species could theoretically use.
• Realized niche to survive and avoid competition,
  a species usually occupies only part of its
  fundamental niche.

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Generalist and Specialist Species Broad and
Narrow Niches

• Generalist species tolerate a wide range of
  conditions.
• Specialist species can only tolerate a narrow
  range of conditions.

Figure 4-7
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Specialist species with a narrow niche
Generalist species with a broad niche
Niche separation
Number of individuals
Niche breadth
Region of niche overlap
Resource use
Fig. 4-7, p. 91
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SPOTLIGHTCockroaches Natures Ultimate Survivors

• 3,500 different species
• Ultimate generalist
• Can eat almost anything.
• Can live and breed almost anywhere.
• Can withstand massive radiation.

Figure 4-A
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ECOLOGICAL NICHES AND ADAPTATION

• Native species
• Normally live in the environment
• Non native species
• Accidentally introduced to the environment
• Invasive or alien species
• Indicator species
• Provide an early warning of damage

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ECOLOGICAL NICHES AND ADAPTATION

• Keystone species
• Have a large effect on types and abundance of
  other organisms
• Have critical roles in the environment
• Foundation species
• Shape communities by creating enhancing habitats

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Specialized Feeding Niches

• No two organisms can share the exact same Niche
  in the exact same place
• Resource partitioning reduces competition and
  allows sharing of limited resources.

Figure 4-8
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Avocet sweeps bill through mud and surface water
in search of small crustaceans, insects, and
seeds
Ruddy turnstone searches under shells and
pebbles for small invertebrates
Herring gull is a tireless scavenger
Brown pelican dives for fish, which it locates
from the air
Dowitcher probes deeply into mud in search
of snails, marine worms, and small crustaceans
Black skimmer seizes small fish at water surface
Louisiana heron wades into water to seize small
fish
Piping plover feeds on insects and
tiny crustaceans on sandy beaches
Oystercatcher feeds on clams, mussels, and other
shellfish into which it pries its narrow beak
Flamingo feeds on minute organisms in mud
Scaup and other diving ducks feed on mollusks,
crustaceans,and aquatic vegetation
Knot (a sandpiper) picks up worms and small
crustaceans left by receding tide
(Birds not drawn to scale)
Fig. 4-8, pp. 90-91
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GENETIC ENGINEERING AND THE FUTURE OF EVOLUTION

• We have used artificial selection to change the
  genetic characteristics of populations with
  similar genes through selective breeding.

• We have used genetic engineering to transfer
  genes from one species to another.

Figure 4-15
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Genetic Engineering Genetically Modified
Organisms (GMO)

• GMOs use recombinant DNA
• genes or portions of genes from different
  organisms.

Figure 4-14
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Phase 1 Make Modified Gene
E. coli
Insert modified plasmid into E. coli
Genetically modified plasmid
Cell
Extract Plasmid
Extract DNA
Plasmid
Gene of interest
DNA
Remove plasmid from DNA of E. coli
Identify and remove portion of DNA with desired
trait
Insert extracted (step 2) into plasmid (step 3)
Identify and extract gene with desired trait
Grow in tissue culture to make copies
Fig. 4-14, p. 95
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Phase 2 Make Transgenic Cell
A. tumefaciens (agrobacterium)
Foreign DNA
E. Coli
Host DNA
Plant cell
Nucleus
Agrobacterium inserts foreign DNA into plant cell
to yield transgenic cell
Transfer plasmid copies to a carrier agrobacterium
Transfer plasmid to surface of microscopic metal
particle
Use gene gun to inject DNA into plant cell
Fig. 4-14, p. 95
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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
Fig. 4-14, p. 95
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Controversy Over Genetic Engineering

• There are a number of privacy, ethical, legal and
  environmental issues.
• Should genetic engineering and development be
  regulated?
• What are the long-term environmental consequences?

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THE FUTURE

• Biologists are learning to rebuild organisms from
  their cell components and to clone organisms.
• Cloning has lead to high miscarriage rates, rapid
  aging, organ defects.
• Genetic engineering can help improve human
  condition, but results are not always
  predictable.
• Do not know where the new gene will be located in
  the DNA molecules structure and how that will
  affect the organism.

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How Would You Vote?

• Should we legalize the production of human clones
  if a reasonably safe technology for doing so
  becomes available?
• a. No. Human cloning will lead to widespread
  human rights abuses and further overpopulation.
• b. Yes. People would benefit with longer and
  healthier lives.