EVOLUTION Ch 15 Notes

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EVOLUTIONCh 15 Notes
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• Theories of Evolution

• Biological evolution change of populations of
  organisms over time, and new organisms develop
  from existing ones

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• Evolutionary Relationships Between Whales and
  Hoofed Mammals

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• Theories of Evolution

• Scientific understanding of evolution began in
  17th and 18th centuries
• Geologists and naturalists compared geologic
  processes and living and fossil organisms around
  the world.

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• Lamarcks Explanation

• Based on Acquired Traits (not determined by
  genes, results from experiences behavior)
• Web feet - from the stretching of tissue between
  toes
• If parents acquire it, they pass to offspring!
• 1st to state organisms change over time

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• Modern Evolutionary Thought

• Darwin Wallace independently proposed (1858)
• Natural Selection - organisms best suited to
  environment, reproduce more successfully
• Favorable traits increase over generations

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Darwins Voyage

• 5 years
• H.M.S. Beagle
• Collected or observed many organisms

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Influences on Darwins Theory

• Lyell (Geologist)
• Uniformitarianism The processes of change are
  the same over time
• Earth was ancient ever- changing
• Cuvier (Anatomist)
• Noticed unique organisms
• catastrophism sudden geologic change
  contributed to mass extinctions
• If Earth Changes, the organisms must too!

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Darwins Findings

• Noted subtle differences in finches tortoises,
  by island compared to mainland
• Descent with modification
• All species have common ancestor
• Natural selection is mechanism for evolution
• POPULATIONS EVOLVE NOT INDIVIDUALS
• AN INDIVIDUAL CAN HAVE A MUTATION

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Darwins Reasoning
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Darwins Reasoning

• 1. Overproduction more offspring produced than
  can survive
• 2. Genetic Variation Within a popl. differences
  exist among individuals
• 3. Struggle to survive Variations may help you
  survive or hinder you
• 4. Differential reproduction those w/ best
  adaptations survive and reproduce the most
• Survival of the fittest has the most viable
  offspring who then continue to reproduce pass
  on good traits

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• Natural Selection

• Organisms in a population adapt to their
  environment as the proportion of individuals with
  genes for favorable traits increase
• Genetic Mutations Lead to Visible Changes in
  Phenotype

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CH 15 NOTES-EVOLUTION
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History of Life on Earth
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• Biogeography

• Distribution of living organisms fossils
• Living organisms look similar to fossils in the
  same area (glyptodont armadillo)

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Coevolution

• 2 or more species evolve together (plant
  pollinator, parasite host)
• Example bacteria antibiotic resistance

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• Convergent Evolution

• Unrelated species develop similar characteristics
  because of environment

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• Divergent Evolution

• Related populations become less similar -
  usually habitat related

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• Divergent Evolution

• Sped up by artificial selection

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Population Genetics and Speciation Ch 16 Notes
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Population Genetics

• Study of evolution from genetic point of view
• Biologists study variation in populations (ex
  size, color)
• Population All members of a species living in
  the same area (can breed w/ each other)

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Causes of Variation

• Mutation
• Recombination-shuffling of genes
• Random fusion of gametes
• Environmental factors amt of food

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Gene Pool

• Total genetic info available in a population
• In the gene pool, there is A or a
• If 6 out of 10 are A the allele frequency of A
  is 0.6
• 4/10 are a 0.4
• Frequency always in decimal form

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Phenotype Frequency

• w/ a certain phenotype divided by total of
  individuals
• 6/10 0.6
• Use frequencies to predict future generations
• Frequency r X Frequency r
• 0.25 x 0.25 rr 0.0625

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Hardy-Weinberg Genetic Equilibrium

• State of equilibirum in which genotype
  frequencies in a population stay the same from
  generation to generation
• Used for comparing real data with that predicted
  by the equilibrium model
• Framework for testing factors that can lead to
  evolution

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Hardy-Weinberg Genetic Equilibrium

• Used to predict genotypic frequencies. 2
  equations
• p2 2pq q2 1
• p q 1
• p2 homozygous dominant
• 2 pq heterozygous
• q2 homozygous recessive
• 1 all possible genes in pop.

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Hardy-Weinberg Genetic Equilibrium

• 5 conditions required for a population to be in
  equilibrium
• Very large population
• No emigration or immigration
• No mutations
• Random mating
• No natural selection

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Hardy-Weinberg Genetic Equilibrium

• 5 factors that can lead to evolution
• - Evolution occurs if/when ____ is present
• 1.Genetic mutations
• 2.Gene flow
• 3.Genetic drift
• 4.Nonrandom mating sexual selection
• 5.Natural selection

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Disrupting Genetic Equilibrium Evolution

• 1. Mutation change in DNA
• 2. Gene flow
• Moving genes btwn populations
• Immigration (move into) or Emigration (move out
  of)
• 3. Genetic Drift
• Change in allele frequency b/c of random event or
  chance
• Harmful alleles can become more common
• Most common in small populations
• Causes a loss of genetic diversity individuals
  cannot adapt
• Bottleneck effect can lead to genetic drift

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Disrupting Genetic Equilibrium Evolution

• 4. Nonrandom mating
• Choosing your mate
• Sexual selection
• Mate is chosen based on characteristics ex
  peacock, frigate birds red pouch, lions mane
• 5. Natural Selection some members more likely to
  survive reproduce

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Bell Curve

• Shows the majority in the population are in the
  middle of a range (height, weight, length)

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Types of Natural Selection

• Stabilizing
• Directional
• Disruptive or diversifying

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Stabilizing Selection

• Average form of the trait has the highest fitness
• Most common
• Results in a population that looks very similar

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Directional Selection

• One side of the extreme form of a trait is the
  most fit (tallest)
• Population goes toward one end of the scale

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Disruptive Selection

• Either extreme variation of the trait is valuable
  
• Population goes toward both ends of scale

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• Species Isolating Mechanisms

• 3 type of Isolating Mechanisms that lead to new
  species
• Geographic Isolation
• Physical separation
• Mountains, lakes etc.

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• Species Isolating Mechanisms

• Reproductive Isolation
• Something besides geography prevents reproduction
• Prezygotic - before fertilization
• Different seasons
• Different calls
• Postzygotic - after fertilization
• Bad wasted gametes if offspring are sterile

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• Species Isolating Mechanisms

• Sympatric Speciation
• Utilizing different niches (food source) leads to
  speciation

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• Rates of Speciation

• Gradualism
• Small changes _at_ constant rate
• Punctuated Equilibrium
• Periods of stability followed by rapid change