More Natural Selection Info

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More Natural Selection Info

• Describe Natural Selection including the 3 things
  needed for it to occur
• Define adaptation
• List and describe five examples of natural and
  artificial selection

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Natural Selection

• 1. There is competition for limited resources
• 2. There is natural variation (behavior, traits)
• 3. The variation is inherited
• The outcome of variation in heritable traits that
  affect survival and reproduction

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Adaptation

• The consequence of natural selection is
  adaptation
• Adaptation some heritable aspect of form,
  function, behavior or development that improves
  the odds for surviving or reproducing in a given
  environment.

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Artificial Selection
http//www.gly.uga.edu/railsback/1122/1122Dogs.jpe
g
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Artificial Selection
http//www.bio.miami.edu/dana/160/artificialselect
ion.jpg
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Natural Selection
http//www.museums.org.za/bio/insects/cockroaches/
http//home-supplies.best-emporium.com/cat-125/Cle
aning-Sanitation/Cleaning-Chemicals/Rodenticide-In
secticides/
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Natural Selection
Staphylococcus aureus antibiotic resistance
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Population Information

• Define population
• Describe the basis and source of heritable
  variation within a population
• If there are heritable variations within a
  population, when does evolution not occur?

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How would you define POPULATION?

• all organisms that constitute a specific group
  (species) in a specific habitat/environment

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Review of Genetics

• Cells are the basic unit of life
• Cells have DNA
• DNA contains genes
• Genes code for proteins, usually enzymes
• Genes that differ slightly are called alleles
• Different alleles make different forms of the
  same enzyme
• These enzymes determine an organisms phenotype
• Alleles can be inherited

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Population Genetics

• Gene pool all the alleles of all the genes in
  all the individuals in a population
• Each organism will have a unique combination of
  alleles and, therefore, a unique phenotype
• Unique combination of alleles
• Mutation
• Crossing-over
• Independent assortment
• Fertilization
• Change in chromosome number or structure

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Population Genetics

• Allele frequency relative proportion of one
  allele for one gene
• Evolution change in the allele frequency within
  a population

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How does Evolution Occur?

• Describe how evolution can occur
• Mutation
• No gene flow
• Small population size
• Non-random mating
• Natural selection
• Disruptive
• Directional
• Stabilizing

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Violation of equilibrium mutation

• Mutations are rare (1/100,000 gametes)
• Mutations can be
• Helpful
• Depends on
• environment
• Neutral
• Harmful
• Lethal mutation

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Gene Flow

• Individuals, and their alleles, move into and out
  of populations
• The physical flow counters the effects of
• mutation
• natural selection
• genetic drift

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Small Population Size

• Hypothesis how often will you get tails?
• Flip a coin ten times
• heads
• tails
• Everyone flip a coin ten times
• heads
• tails
• Discuss the difference between 10 and 200 events
  sampling error

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Small Population

• Random events can have drastic effects on the
  allele frequencies in a small population Genetic
  Drift
• Two examples
• Founder effect
• Bottleneck

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phenotypes of original population
Founder Effect
A seabird carries a few seeds, stuck to its
feathers, from the mainland to a remote oceanic
island.
phenotype of island population
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Bottleneck Effect Elephant seal
Reduction of a populations gene pool produced
when a few members survive the widespread
elimination of a species.
Año Nuevo State Park
http//www.aad.gov.au/default.asp?casid1239
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Non-random mating

• Do humans mate randomly?
• How do people pick a mate?

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Non-random mating 3 types

• Assortive shifts genotype frequency
• Organisms choose a mate with the same genotype as
  themselves.
• Organisms choose a mate with a different genotype
  from themselves.
• Self-fertilization shifts genotype frequency
• Organism mates with itself
• Sexual selection shifts allele frequency
• Some genotypes mate more successfully than others

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Assortive Mating
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Self-fertilization
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Sexual selection
http//subjunctive.net/photoblog/2003/peacock-wooi
ng-peahen.jpg
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Natural Selection

• Evolution due to natural selection results from
  unequal reproduction of various alleles
• Natural selection acts on phenotypes but affects
  genotypes
• Adaptations help an individual survive and
  reproduce

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Agents of Natural Selection

• Abiotic factors
• Climate
• Geology
• Other non-living factors
• Biotic factors
• Competition
• Food, Shelter, Mating
• Interspecies Interactions
• Predation
• Sexual Selection

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3 Modes of Natural Selection Directional
Selection
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Number of individuals
3 Modes of Natural Selection Stabilizing
Selection
Range of values at time 1
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3 Modes of Natural Selection Disruptive
Selection
Number of individuals
Range of values at time 1