Chapter 23 The Evolution Of Populations Ap Biology Essays

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Welcome Students. The First section lists a ton of study sites for you to use as a reference throughout the year with practice AP exams and quizzes.  After the photos section is each unit's information, in order with support materials.



  Please feel free to email me @  if you have any questions.


STUDY TOOLS FOR YOU! (ALL Individual Unit Information begin after photos)



  -Lab Tutorials and Pre-lab Animations and Questions
      (Lab Bench AP Lab Tutorials)
 2)  AP BIOLOGY FLASH CARDS (all terms from each chapter!!)
        (chapters are off by one...our chapter 24 is their chapter 23)


 3)  BIOCOACH ACTIVITIES (helps review major concepts from each unit with quiz)



  4) PRACTICE TESTS AND QUIZZES FOR EACH UNIT!!! (check this out; worth doing!!




















   11)  Review AP Exams from REVIEW BOOKS

       - CampaignID=9248


  12) Cummulative list of ALL VOCAB TERMS/ALL CHAPTERS:   see how many you know!!




  1. Hamster Research Links
  • Hamster Genetics  (use this link for genetic info: we have Dwarf Campbell Russians...follow "Genetics" links to determine which traits are dominant).
  • Additional Hamster Genetics  (Hamster Genetics Direct Link)

AP Biology Dunes Succession Field Study, MILLER DUNES/PAUL H. DOUGLAS CENTER in Gary, Indiana. (September 23, 2011)

(AP Biology Macroinvertebrate Field Study, Bartel Grasslands and Frankfort Square
October, 2010)




(AP Biology Students at Indiana Dunes, Oct. 1, 2012 and Prairie, Yankee Woods

and Bartel Grasslands, November 20, 2012)




INTRODUCTION UNIT:  Themes/Experimental Design & Statistics

a) Chapter 1 Scientific Inquiry/Data Analysis

  • Emergence Video NOVA                                                                                                                                                                                

b)  StatisticsTutorials (Khan Academy) 


c) Statistics Labs with M&M's

d)  Practice Test Questions (Click on the

Unit I:  Biochemistry (Chapters 2-5)

Chapter 2:  Basic Chemistry Review 
 -Chapter 2 NOTES

 -Chapter 2 Powerpoint Notes
 -Chapter 2 Homework Study Guide
 -Chapter 2 Activity
- Emergent Properties Video
-Animations and Tutorials  (bonding, atomic number, ect)      

 -Bozeman Biology Tutorials                                                                                                                                                                  


  -Chapter 2 Practice Test   (click on chapter; select maximum question number 0f 40 )                                                                                                                                                                                                                                                                                    
Chapter 3:  Properties of Water
  • -Water Powerpoint
  • -Chapter 3 Notes Water Chemistry
  •  -Chapter 3 Homework Study Guide
  • -Water Properties Activity (Book)
  • -Bozeman Biology Tutorials                                                                                                                                                                                                           
- Chapter 3 Animations 
  • -pH Animation
  • -pH Tutorial
  • -Buffer Animation
  • - Lecture on Acid/Base/Buffers and pKa
  • -Cat drinking water
  • -Dog drinking water 


    • Chapter 3 Practice Test   (click on chapter; select maximum of 40 )                                                                                                                                                                                                       


Chapter 4:  Carbon Chemistry


Chapter 5 Macromolecules


Carbs Notes

Carbs Study guide

Lipid Notes

Lipid Studyguide

Protein Notes

Protein Study Guide

Nucleic Acids Notes

Nucleic Acid Study Guide



Extra Worksheets

Worksheet 4/5.1 Identify Macromolecules

Worksheet 4/5.2 Macromolecules

Chart Cheat Sheet for Macromolecules
Amino acids chart

ANIMATIONS Of Biological Molecules (Lipids, Proteins, Carbs, Nucleic Acids)
macromolecules animation
step by step biomolecules tutorial with quiz
types of chemical reactions animation
hydrolysis/dehydration synthesis animation 1
hydrolysis/dehydration synthesis animation 2
You tube animation of biomolecules (good one)
Protein Folding (know this one1)
Protein Folding and pH Animation
Protein Folding Again
Advanced Protein Folding
Amino Acids and pH animation

Review Self-Quizzes
Chapter 5 Practice quiz (Choose Chapter)
Functional groups Quiz Interactive
DNA vs. RNA quiz

Unit II:  Cell Energy  (Chapters 8-10)


Chapter 8 Thermodynamics/Enzymes



  1. Gibbs Energy and Thermodynamics Online Tutorials
  1. ENZYMES Animations and Tutorials


  1. Enzyme Lab #2:  One of the "Big 13" 





Chapter 9 Respiration


Chapter 10 Photosynthesis  

         look at all of the photosynthesis quizzez and take them...use the animations for photosynthesis under "Web Links" as

         a wonderful tutorial.  These worksheets and quizzez will be used in class as study tools. 



Unit III: Ecology Unit (CHAPTERS 51-55)

  • Chapter 51 Animal Behavior


  • Chapter 50 and 52:  Introduction to the Biosphere and Population Ecology


  • Chapter 52 Video Lecture:  Population Ecology   
      • Watch Population Ecology:  Unlimited Resources
      • Watch Population Ecology:  Limited Resources
      • Watch Population Ecology:  r versus K
      • Watch Pop. Ecol:  Intraspecific competition
      • Watch Pop. Ecol:  Interspecific competition
      • Watch Pop. Ecol:  Predation
      • Watch Pop. Ecol:  Niches and ALSO symbiosis!!



Chapter 53:  Community Ecology 


Semester 1 Ecology Review Question Answers (1-44)

Sem1 Ecology Sample Questions Review Answers


Unit IV:   Cell Biology Ch. 6,7,11,12


  • Cell Video Lectures Cell Techniques   (if you can't find video directly through link, search under my mindbites)


  • Cell Video Lectures, Cell Structure and Organelles

Chapter 7 Cell Membranes/Transport

Presentation on theme: "Chapter 23: The Evolution of Populations"— Presentation transcript:

1 Chapter 23: The Evolution of Populations

2 Essential Knowledge1.a.1 – Natural selection is a major mechanism of evolution (23.2).1.a.2 – Natural selection acts on phenotypic variations in populations (23.1 & 23.4).1.a.3 – Evolutionary change is also driven by random processes (23.3).2.c.1 – Changes in genotype can result in changes in phenotype (23.4).4.c.3 – The level of variation in a population affects population dynamics (23.1 – 23.3).4.c.4 – The diversity of species within an ecosystem may influence the stability of the ecosystem (23.2).

3 Question? Is the unit of evolution the individual or the population?
Answer – while evolution affects individuals, it can only be tracked through time by looking at populations.

4 So what do we study? We need to study populations, not individuals.
We need a method to track the changes in populations over time.This is the area of Biology called population genetics.

5 Population Genetics The study of genetic variation in populations.
How do populations change, genetically, over time?Represents the reconciliation of Mendelism and Darwinism.

6 Population A localized group of individuals of the same species.
Must produce viable offspring

7 Species A group of similar organisms.
A group of populations that could interbreed (successfully)Populations are animals of the same species that are isolated due to geography

8 Gene Pool The total aggregate of genes in a population.
All alleles at all gene loci in all individualsIf evolution is occurring, then changes must occur in the gene pool of the population over time.

9 MicroevolutionChanges in the relative frequencies of alleles in the gene pool.Micro = smallMicroevolution is how we study evolution at the genetics level

10 Hardy-Weinberg Theorem
Developed in 1908.Use as a benchmark to study evolutionary change in a populationMathematical model of gene pool changes over time.

11 H-W TheoremStates:The frequencies of alleles and genotypes in a population’s gene pool remain constant (in a population that is NOT evolving)

12 Basic Equation p + q = 1 p = %/frequency of dominant allele
q = %/frequency of recessive allele

13 Expanded Equation p + q = 1 (p + q)2 = (1)2 p2 + 2pq + q2 = 1
We expand the equation to “fit” all three types of genotypes (Ex: AA, Aa, aa)

14 Genotypesp2 = Homozygous Dominant frequency 2pq = Heterozygous frequency q2 = Homozygous Recessive frequency

15 Example Calculation Let’s look at a population where: A = red flowers
a = white flowers


17 (hence the “2” in the equation)
Starting PopulationN = 500Red = 480 (320 AA+ 160 Aa)White = 20Total Genes/Alleles= 2* x 500 = 1000*2 alleles per genotype(hence the “2” in the equation)

18 Dominant Allele A = (320 x 2) + (160 x 1) = 800 = 800/1000 = 0.8 = 80%
2 = # of times the dom allele is present in homozy dom genotype1 = # of times the dom allele is present in heterozy genotypeA = (320 x 2) + (160 x 1) = 800= 800/1000 = 0.8 = 80%320 = AA pop # (2 = # of dominant alleles in that AA genotype);160 = Aa pop # (1 = # of dominant alleles in Aa genotype);1000 = total genes

19 Recessive Allele a = (160 x 1) + (20 x 2) = 200 = 200/1000 = .20 = 20%
2 = # of times the rec allele is present in homozy rec genotype1 = # of times the rec allele is present in heterozy genotypea = (160 x 1) + (20 x 2) = 200= 200/1000 = .20 = 20%20 = aa pop # (2 = # of recessive alleles in that aa/white genotype);160 = Aa pop # (1 = # of recessive alleles in Aa genotype);1000 = total genes

20 Importance of Hardy-Weinberg
Yardstick to measure rates of evolution.Predicts that gene frequencies should NOT change over time as long as the H-W assumptions hold.Way to calculate gene frequencies through time.

21 Example What is the frequency of the PKU allele?
PKU is expressed only if the individual is homozygous recessive (aa).

22 PKU Frequency PKU is found at the rate of 1/10,000 births.
PKU = aa = q2q2 = .0001q = .01 (frequency of recessive alleles)

23 Dominant Allelep + q = 1p = 1- qp =p = .99

24 Expanded Equation p2 + 2pq + q2 = 1 (.99)2 + 2(.99x.01) + (.01)2 = 1
= 1Freq of Homozy Dom genotypeFreq of Heterozy genotypeFreq of Homozy Rec genotype

25 Final ResultsAll we did is convert the frequencies (decimals) to % (by multiplying frequencies by 100%)Normals (AA) = 98.01%Carriers (Aa) = 1.98%PKU (aa) = .01%

26 AP Problems Using Hardy-Weinberg
Solve for q2 (% of total)Solve for q (equation)Solve for p (1- q)H-W is always on the national AP Bio exam

27 Hardy-Weinberg Assumptions
1. Large Population2. Isolation3. No Net Mutations4. Random Mating5. No Natural Selection

28 If H-W assumptions hold true:
The gene frequencies will not change over time.Evolution will not occur.How likely will natural populations hold to the H-W assumptions?

29 MicroevolutionCaused by violations of the 5 H-W assumptions.

30 Causes of Microevolution
1. Genetic Drift2. Gene Flow3. Mutations4. Nonrandom Mating5. Natural Selection

31 Genetic DriftChanges in the gene pool of a small population by chance.Types:1. Bottleneck Effect2. Founder's Effect

32 By Chance

33 Bottleneck Effect Loss of most of the population by disasters.
Surviving population may have a different gene pool than the original population.Results: Some alleles lost, others are over-represented, genetic variety is decreased


35 ImportanceReduction of population size may reduce gene pool for evolution to work with.Ex: Cheetahs

36 Founder's EffectGenetic drift in a new colony that separates from a parent population.Ex: Old-Order AmishResults: Genetic variety reduced, some alleles increase while other lost

37 ImportanceVery common in islands and other groups that don't interbreed.

38 Gene Flow Movement of genes in/out of a population. Ex:
ImmigrationEmigrationResult: change in gene frequency

39 MutationsInherited changes in a gene.

40 Result May change gene frequencies (small population).
Source of new alleles for selection.Often lost by genetic drift.

41 Nonrandom MatingFailure to choose mates at random from the population.

42 Causes Inbreeding within the same “neighborhood”.
Assortative mating (like with like).

43 Result Increases the number of homozygous loci.
Does not in itself alter the overall gene frequencies in the population.

44 Natural Selection Differential success in survival and reproduction.
Result - Shifts in gene frequencies.

45 CommentAs the environment changes, so does natural selection and gene frequencies.

46 ResultIf the environment is "patchy", the population may have many different local populations.

47 Genetic Basis of Variation
1. Discrete Characters – Mendelian traits with clear phenotypes.2. Quantitative Characters – Multigene traits with overlapping phenotypes.

48 PolymorphismThe existence of several contrasting forms of the species in a population.Usually inherited as Discrete Characteristics.

49 ExamplesGarter SnakesGaillardia

50 Human ExampleABO Blood GroupsMorphs = A, B, AB, O

51 Quantitative Characters
Allow continuous variation in the population.Result –Geographical VariationClines: a change along a geographical axis

52 Yarrow and Altitude

53 Sources of Genetic Variation
Mutations.Meiosis - recombination though sexual reproduction.Crossing-overRandom fertilization

54 CommentPopulation geneticists believe that ALL genes that persist in a population must have had a selective advantage at one time.Ex – Sickle Cell and Malaria, Tay-Sachs and Tuberculosis


56 Fitness - DarwinianThe relative contribution an individual makes to the gene pool of the next generation.How likely is it that an organism will survive and reproduce in a given environment?

57 Relative FitnessContribution of one genotype to the next generation (when compared to other genotypes)

58 Rate of Selection Differs between dominant and recessive alleles.
Selection pressure by the environment/nature.

59 Modes of Natural Selection
1. Stabilizing 2. Directional 3. Diversifying 4. Sexual

60 Stabilizing Selection toward the average and against the extremes.
Ex: birth weight in humans

61 Directional Selection
Selection toward one extreme.Ex: running speeds in race animalsEx. Galapagos Finch beak size and food source


63 Diversifying(Disruptive)
Selection toward both extremes and against the norm.Ex: bill size in birds

64 CommentDiversifying Selection - can split a species into several new species if it continues for a long enough period of time and the populations don’t interbreed.


66 Sexual Mate selectionMay not be adaptive to the environment, but increases reproduction success of the individual.

67 Result Sexual dimorphism.
Secondary sexual features for attracting mates.

68 CommentsFemales may drive sexual selection and dimorphism since they often "choose" the mate.

69 Question Does evolution result in perfect organisms? No!? Compromises
Chance occurrences

70 Summary Recognize the modern synthesis Theory of Evolution.
Identify and use the Hardy-Weinberg Theorem for population genetics.Identify the Hardy-Weinberg assumptions and how they affect evolution of populations.Recognize causes and examples of microevolution.Identify modes of natural selection.Recognize why evolution does not produce "perfect" organisms.

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