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Welcome to AP Biology
Saturday Study Session
Microevolution
Microevolution
Mutations
Non-random Mating
Gene Flow
Genetic Drift
Natural Selection
5 FINGERS OF
EVOLUTION
Question 1
b
Clue: small population size
Types of Genetic Drift
1. Bottleneck effect: populations are
dramatically reduced due to a
catastrophe; only a few individuals
survive to pass on their reduced
number of genes.
2. Founder effect:
4
Question 2
d
Clue: the resistant phenotype is favored
Artificial Selection Backfiring
Question 3
c
Clue: differential reproductive success
leads to changes in allele frequencies
Question 4
a
Clue: decreased genetic diversity
Populations
with little
genetic diversity
are at risk for
extinction
N = number of black-footed ferrets
A0 (triangles) = number of alleles per locus
P (diamonds) = proportion of polymorphic loci
He (squares) = frequency of heterozygotes per locus
Question 5
b
Clue: heterozygotes maintain variation
Question 6
c
Clue: the frequency of lap94 allele
increases with increased salinity
Genetic
changes that
enhance
survival and
reproduction
can be
selected by
environmental
conditions
Question 7
b
Clue: ↓ small seeds =↓ small beaks
Original
population
Evolved
population
Directional
selection
Types of
Natural Selection
Disruptive
selection
Stabilizing
selection
Math Grid In 1
The correct answer: 0.0002
Solution:
• Affected (p2 + 2pq) = 34 individuals
• Unaffected (q2) = 100,000 – 34 = 99,966
individuals
• q2 = 99966/100,000
• q = √.99966 = 0.99983
• p = 1 - q = 1 - 0.99983 = 0.00017 = 0.0002
Short Free Response 1
3 points possible
a. 1 pt for evidence
• New genotypes/phenotypes OR DNA/chromosomal differences OR different
mRNA sequence OR protein with different amino acid sequence
b. 1 pt for mechanism
• Meiosis/sexual reproduction
• Crossing over /independent assortment/random fertilization
• Immigration/gene flow
• Viral infection inserts DNA into genome
• Point mutations/chromosomal rearrangements
• Radiation/chemicals induce mutations
c. 1 pt for description
• Genetic variation is the basis of phenotypic variation that can be acted upon by
natural selection.
• Without genetic variation, there is no phenotypic variation on which natural
selection can act.
Mechanisms
of Genetic Variation
CROSSING OVER
Prophase I of meiosis
RANDOM FERTILIZATION
Which sperm will it be?
Mechanisms of Genetic Variation
INDEPENDENT ASSORTMENT
Metaphase I of meiosis
Mechanisms of Genetic Variation
POINT MUTATIONS
CHROMOSOME MUTATIONS
Mechanisms of Genetic Variation
CONJUGATION
TRANSFORMATION
TRANSDUCTION
TRANSPOSITION
Short Free Response 2
5 points possible
a. 3 points maximum
• Correctly labeled graph, scaled, with proper units
• Bar graph with appropriately plotted means
• 2x standard error (SEM) above and below means
b. 2 points maximum
• Identification – 1 pt: the two populations are statistically
different
• Justification – 1 pt: the error bars/95 percent confidence
intervals for the two populations do not overlap
Leaf Mass per Area (mg/cm2)
Means of leaf mass per area for B. forficata trees grown in
forests gaps and understory
5.5
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Forest Gaps
Understory
Growing Environment