Question of the Day Mar 14

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Question of the Day Mar 14

• Which is not true about a species?
• A. Members live in populations
• B. They cannot breed with one another
• C. They can breed between different populations.
• D. All members contribute to the species gene
  pool.

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AGENDA Mar 14

• Objective Investigate how genetic variation is
  responsible for natural selection.
• 1. Question of the DAY
• 2. Chapter 16-1 Genes and Variation3. Homework
  Check 16-1 Guided Reading
• 4. Review and Homework
• 16-2 Guided Reading

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Chapter 16

• Evolution of
• Populations

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16-1 Genes and Variation

• natural selection relies on variation
• genes are the source of inheritable variation
• when variation occurs, nature selects the
  successful ones
• individuals do not change, a population does

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Genes and Variation

• At least two different alleles account for
  inherited traits.
• Body size, coat color, seed shape
• Invisible variation also present
• Small differences in biochemical processes

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Genes and Variation

• Individual organisms are heterozygous for many
  genes
• 15 of genes in insects
• 4 8 in fish, reptiles, and mammals

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Evolution as Genetic Change

• evolutionary biologists study populations
• collection of individuals of the same species in
  a given area
• share a gene pool
• relative frequency number of times an allele
  occurs in a gene pool compared with the number of
  times other alleles for the same gene occur
• What is the relative frequency of the purple
  allele?

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Genetic Variation within a Species

• species group of similar organisms that breed
  with each other and produce viable offspring
  because they share the same gene pool
• How do mutations occur?
• Mistakes in replication, radiation, and chemicals
• Gene Shuffling - Meiosis

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Genetic Variation within a Species

• How many different combinations of genes can be
  produced from homologous x-somes in a human?
• 8.4 million
• Number of phenotypes produced for a trait depends
  on how many genes control the trait
• Single-gene trait
• Polygenic trait

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Single-gene and Polygenic
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QUESTION of the DAY Mar 17

• The success of an organism in surviving and
  reproducing is a measure of
• A. an adaptation to an environmental factor
• B. its fitness
• C. its polygenic traits
• D. single gene traits

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AGENDA Mar 17

• Objective Explain the five conditions needed to
  maintain genetic equilibrium.
• 1. Question of the DAY
• 2. Chapter 15 Test Grades in GENESIS
• 3. Chapter 16-2 Evolution as Genetic Change4.
  Homework Check 16-2 Guided Reading
• 5. Review and Homework

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16-2 Evolution as Genetic Change

• Why does natural selection never act on specific
  genes?
• An entire organism either survives and reproduces
  or dies out.
• Organisms that die do not contribute to gene
  pool.
• Relative frequencies within a population change
  over time.

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Natural Selection on Single Gene Traits

• Leads to changes in allele frequencies
• Consider a population of lizards
• Normal skin Brown
• Mutations produce Red and Black skin
• Predict the number of red lizards after 30
  generations if the environment the lizards live
  in is a desert.
• Black lizards? WHY?

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Natural Selection on Polygenic Traits

• What type of curve is produced when measuring a
  range of phenotypes?
• Bell curve
• Interpret the phenotypes found within the
  individuals of this population.

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Three types of Selection

• Directional Selection individuals at one end of
  the curve have higher fitness than those in
  middle or at the end.
• Dotted line Original
• distribution of
• individuals

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Types of Selection

• Stabilizing Selection Individuals near the
  center of the curve have higher fitness than any
  other individuals.
• Dotted line Original
• distribution of human
• babies

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Types of Selection

• Disruptive Selection Individuals at upper and
  lower ends of curve have higher fitness than
  those in the middle.
• Dotted line Original
• distribution of
• individuals

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Types of Adaptations

• Morphological Adaptation Structural feature that
  aids a species in fitting into its environment.
• Physiological Adaptation An adjustment of the
  body involving metabolic processes that allows
  an organism to best adapt to its environment.
• Behavioral Adaptation Traits that develop to
  better allow an organism to survive or reproduce.
• Bears hibernating in winter
• Sheep running away from types of noises

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Examples
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QUESTION of the DAY Mar 18

• When average sized seeds become more scarce but
  smaller and larger seeds are still available as
  food sources, the type of selection that
  represents this change is
• A. Directional
• B. Disruptive
• C. Stabilizing
• D. Drifting

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AGENDA Mar 18

• Objective Apply Hardy-Weinberg equations to
  determine allele frequencies.
• 1. Question of the DAY
• 2. Chapter 16-2 Hardy-Weinberg Equilibrium
• Problem Solving
• 3. Review and Homework

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GENETIC DRIFT

• What controls genetics and the passing down of
  genes?
• PROBABILITY
• Genetic drift random change in the frequency of
  a gene that happens by chance
• Greater of changes as population sizes decrease
• Founder effect change in allele frequencies due
  to the migration of a small subgroup of
  individuals.

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Hardy-Weinberg Principle

• states that allele frequencies in a population
  will remain constant unless one or more factors
  cause those frequencies to change
• only applies during genetic equilibrium when
  allele frequencies remain constant
• Conditions to maintain equilibrium
• random mating
• very large population
• no movement into or out of the population
• no mutations
• no natural selection

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Calculating Gene Frequencies

• when a population is in Hardy-Weinberg
  equilibrium, genotypes can be calculated from
  allele frequencies
• p q 1 p2 2pq q2 1
• p dominant allele
• q recessive allele
• p2 homozygous dominant
• 2pq heterozygous
• q2 homozygous recessive

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Hardy-Weinberg Problems

• In a population of 3000 fruit flies, 270 flies
  have white eyes. White eye color is the recessive
  trait. Determine the frequencies of the red and
  white eye color alleles. How many flies are
  heterozygous for red eye color?
• APPLY the 2 H-W Equations.

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SOLUTION

• STEP 1 Determine q2
• STEP 2 Find q and p
• STEP 3 Determine p2
• STEP 4 Find 2pq
• STEP 5 Find of heterozygous flies

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Hardy-Weinberg Problem

• Coloration in the scarlet tiger moth is listed
  below for 1612 individuals.
• White-spotted (AA) 1469
• Intermediate (Aa) 138
• Little spotting (aa) 5
• Calculate the following frequencies.
• A, a, AA, Aa, and aa

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16-3 The Development of New Species

• speciation process in which new species evolve
  from old ones
• niche combination of an organisms profession
  and the place it lives
• no two species can occupy the same niche in the
  same location for a long period of time
• any species that occupies an unoccupied niche
  will better survive and potentially form a new
  species

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Process of Speciation

• new species form when populations are separated
• reproductive isolation when populations are
  separated so they do not interbreed
• when populations better adapt to different
  environments, their gene pools become dissimilar
• Darwins finches

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Mechanisms of Reproductive Isolation

• Behavioral isolation two populations
• Capable of interbreeding
• Differences in courtship rituals or reproductive
  strategies
• Eastern and western meadowlarks
• Different mating songs
• http//www.bing.com/videos/search?qanimalcourtsh
  ipdisplaysFORMHDRSC3viewdetailmidB99AA83542
  EC45E6463EB99AA83542EC45E6463E

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Mechanisms

• Geographic isolation two population separated
  by geographic barriers
• Mountains, rivers, bodies of water
• Does not guarantee isolation.
• May not isolate every organism from one another

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Mechanisms

• Temporal isolation two or more species
  reproduce at different times.
• Similar orchids living in a rain forest.
• Each releases pollen at a different time

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Peter and Rosemary Grant

• Tested natural selection
• Documented effects in finches on Galapagos
• Individual birds with different beak sizes had
  different chances of survival during a drought
• Big-beaked birds
• obtain food when scarce
• mate with other big-beaked birds

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Speciation in Darwins Finches

• 1. Founders species first finches arrive on
  Galapagos
• 2. Geographic isolation - Some finches arrived on
  another island and adapted to survive
• 3. Different Gene Pools on each island
• 4. Reproduction isolation Two species on same
  island
• finches mate with those having same beak size
• 5. Competition both species compete on same
  island
• 6. Continued evolution produced 13 different
  species

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Speciation and Adaptive Radiation

• adaptive radiation process in which one species
  gives rise to many species
• also known as divergent evolution
• convergent evolution process in which different
  species evolve to have similar appearances and
  behaviors
• analogous structures structures that are similar
  in appearance and function but have different
  origins

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Pace of Evolution

• punctuated equilibrium involves long periods of
  stability that are interrupted by episodes of
  rapid change
• gradualism evolution occurs slow and steady over
  a long period of time