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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