1. Domain 1: Evolution

2. Evolution
"In the broadest sense, evolution is merely change, and so is all-pervasive; galaxies, languages, and political systems all evolve. Biological evolution ... is change in the properties of populations of organisms that transcend the lifetime of a single individual. The ontogeny of an individual is not considered evolution; individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are inheritable via the genetic material from one generation to the next. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions.“
- Douglas J. Futuyma in Evolutionary Biology, Sinauer Associates 1986

3. ULTIMATE RESULT OF EVOLUTION
Change in the genetic composition (gene pool) of a population.

4. MICROEVOLUTION VS. MACROEVOLUTION
Microevolution: survival through the inheritance of favorable characteristics
mutations
selection
Macroevolution: progression of biodiversity through geological time
speciation
extinction

5. MICROEVOLUTION Evolutionary Mechanisms Types of Natural Selection
Hardy-Weinberg Equilibrium

6. WHAT IS MICROEVOLUTION?
Traces generational changes in a population of organisms
Changes eh?
Allelic frequency changes within a
gene pool!

8. WHAT LEADS TO CHANGES IN THE GENE POOL OF A POPULATION?
SMALL POPULATION SIZE
small pop  frequencies
(toss a coin to prove it)

9. MECHANISMS OF EVOLUTION
GENETIC DRIFT
Random/chance events that change the gene pool of a small population
examples:
natural disasters

10. 2 TYPES OF GENETIC DRIFT MECHANISMS
Genetic Bottleneck
Dramatic decrease in pop size due to :
~ catastrophes
~ predation
~ disease, etc.

13. 2 TYPES OF GENETIC DRIFT MECHANISMS
Founder Effect
Migration leads to changes in allele frequencies from population of
origin

17. WHAT ELSE CAUSES GENE POOL CHANGES ?
GENE FLOW
~ immigration
~ emigration

18. EX OF GENE FLOW IN HUMANS
Frequency of Rh - allele among Africans:
63%
Frequency of Rh - allele among African-Americans
45%
Frequency of Rh - allele among White European population 3%

19. WHAT ELSE CAUSES GENE POOL CHANGES ?
MUTATIONS
may produce a selective advantage
may produce deleterious effects
may be harmless

20. WHAT ELSE CAUSES GENE POOL CHANGES ?
NATURAL SELECTION!
increases/decreases allele frequencies due to environmental impact.
Ex: English Peppered Moths

21. WHAT ELSE CAUSES GENE POOL CHANGES ?
NON-RANDOM MATING
individuals choose based upon traits
(vertebrates)
individuals “choose” based upon
physical proximity
(invertebrates)

22. OTHER FORMS OF NON-RANDOM MATING:
WHAT ELSE CAUSES GENE POOL CHANGES ?
OTHER FORMS OF NON-RANDOM MATING:
INBREEDING
Proximity issues
SEXUAL SELECTION:
Male competition:
# offspring  fitness
Female choice:
quality offspring  fitness

23. SEXUAL SELECTION
Picky females, show-off males…

24. MICROEVOLUTION REVIEW
Changes in the GENE POOL!
Caused by:
Gene Flow
Natural Selection
Mutations
Non-Random Mating
Sexual Selection
Inbreeding

25. THE SIGNIFICANCE OF SELECTION
Selection increases the adaptive qualities of a population for the environment in which it lives.
Types of Selection:
Natural Selection
determined by phenotype
selection toward phenotypes that improve fitness

26. SUBDIVISIONS OF NATURAL SELECTION…
Stabilizing Selection
Eliminates individuals with extreme traits. Results in decreased variation

27. Directional Selection
Favors traits at ONE extreme
ex: resistance to insecticides

28. DIRECTIONAL SELECTION
                                                               

29. Disruptive Selection
Selection toward BOTH extremes. Extreme traits are favored, common traits are NOT!
Results in major divisions in population!
What might result?

30. DISRUPTIVE SELECTION
                                                               

31. ARTIFICIAL SELECTION
Directional selection determined by humans

33. Mutation is the ultimate source of variation
CAUSES OF VARIATION
Mutation is the ultimate source of variation
Two major types of mutations:
Gene mutations
Chromosome mutations

34. GENE MUTATIONS
Addition / Insertion
Deletion
Substitution
Inversion

36. SPECIFIC EXAMPLES OF MUTATIONS
Gene mutations
PKU (phenylketonuria)
CF (cystic fibrosis)
Chromosome mutation
Klinefelter syndrome (male with 47,XXY karyotype)

37. ONCE MUTATIONS HAVE ARISEN, FURTHER VARIATION RESULTS FROM:
Recombination of alleles during meiosis
Recombination of alleles during fertilization

38. ONCE GENETIC VARIATION HAS ARISEN, THERE IS ALSO PHENOTYPIC VARIATION.
Recall that, according to Darwin’s Theory, due to competition within populations, there is …
Differential Reproduction of Selected Phenotypes

39. GREAT EXAMPLE OF DIFFERENTIAL REPRODUCTION OF SELECTED PHENOTYPES:

40. ULTIMATE RESULT OF EVOLUTION
Change in the genetic composition (gene pool) of a population.

41. RELATED CAUSES OF GENETIC VARIATION
Sexual Reproduction!
Diploidy
Outbreeding

42. MINORITY ADVANTAGE… 50/50 Sex Ratio
Predation (more common phenotype preferred by predator)
The Lefty Hypothesis
10-15 % general population
>50% contact sports (esp. males)

43. REPRODUCTIVE ISOLATION
Prezygotic
Temporal isolation
Behavioral isolation
Mechanical isolation
Ecological isolation
Gametic isolation
Postzygotic
Hybrid inviability
Hybrid sterility
Hybrid breakdown

44. ALLOPATRIC SPECIATION

45. SYMPATRIC SPECIATION

46. GRADUALISM Species A evolves to become species B.
LONG, GRADUAL process!

47. PUNCTUATED EQUILIBRIUM
Evolution is Slow with brief periods of rapid development of new species.

49. THE HARDY WEINBERG LAW
If allele frequencies for a population do not change…
NO EVOLUTION IS OCCURRING!
Genetic Equilibrium
Hardy Weinberg Equilibrium

50. GENETIC EQUILIBRIUM OCCURS ONLY IF THERE IS…
A large breeding population
Random mating
No change in allelic frequency due to mutation
No immigration or emigration
No natural selection

51. EQUILIBRIUM REQUIRES…
Large Population Size
(laws of probability must apply)
Isolation of Population
(no immigration/emigration to/from other populations)
NO MUTATIONS ALLOWED!
NO NATURAL SELECTION !
all traits must be selectively neutral
Mating Must Be RANDOM
equal probabilities of mating btwn genotypes

55. IS HW EQUILIBRIUM POSSIBLE?
YES ? / NO ?
WHY / WHY NOT??

56. http://zoology. okstate
4e_15-6-OSU.swf

57. THE HARDY-WEINBERG EQUATION
Given one locus with two alleles (A,a) the frequency of either allele is described by a number from zero to one:
allele absent from pop  freq = 0
same allele in all indiv in pop 
freq = 1

58. WHAT IF BOTH ALLELES ARE PRESENT IN A POPULATION?
Frequency of both alleles is equal to
p + q = 1
[p = dominant allele (A)]
[q = recessive allele (a)]
Knowing the frequency of one allele allows for the calculation of the other…
p = 1- q ; q = 1 - p

59. If p+q=1,
then (p+q)2 = 1.
Expand it and get…
p pq q2 = 1

60. WHAT DOES IT ALL MEAN GENOTYPICALLY?
p2 = frequency of AA
2pq = frequency of Aa
q2 = frequency of aa

61. PROBLEM 1
In pigs, the allele for black coat (b) is recessive to the allele for pink coat (B).

62. WHAT % OF PIGS ARE HETEROZYGOUS FOR PINK COAT?

63. In a certain population of 1000 fruit flies, 640 have red eyes while the remainder have sepia eyes. The sepia eye trait is recessive to red eyes. How many individuals would you expect to be homozygous for red eye color?
PROBLEM 2

64. PROBLEM 3
Phenylketonuria (PKU) is a human metabolic disorder that results in mental retardation if it is untreated in infancy. In the United States, one out of approximately 10,000 babies is born with the disorder. Approximately what percent of the population are heterozygous carriers of the recessive PKU allele?

65. IF 9% OF AN AFRICAN POPULATION IS BORN WITH A SEVERE FORM OF SICKLE-CELL ANEMIA (SS), WHAT PERCENTAGE OF THE POPULATION WILL BE MORE RESISTANT TO MALARIA BECAUSE THEY ARE HETEROZYGOUS(SS) FOR THE SICKLE-CELL GENE?