MICROEVOLUTION VS. MACROEVOLUTION - PowerPoint PPT Presentation

Loading...

PPT – MICROEVOLUTION VS. MACROEVOLUTION PowerPoint presentation | free to view - id: 53f0e9-MTBmN



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

MICROEVOLUTION VS. MACROEVOLUTION

Description:

Title: MICROEVOLUTION VS. MACROEVOLUTION Author: rbeck Last modified by: rbeck Created Date: 3/13/2009 10:19:50 PM Document presentation format: On-screen Show – PowerPoint PPT presentation

Number of Views:722
Avg rating:3.0/5.0
Slides: 63
Provided by: rbe69
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: MICROEVOLUTION VS. MACROEVOLUTION


1
MICROEVOLUTION VS. MACROEVOLUTION
  • Microevolution survival through the inheritance
    of favorable characteristics
  • mutations
  • selection
  • Macroevolution progression of biodiversity
    through geological time
  • speciation
  • extinction

2
MICROEVOLUTION
  • Evolutionary Mechanisms
  • Types of Natural Selection
  • Hardy-Weinberg Equilibrium

3
WHAT IS MICROEVOLUTION?
  • Traces generational changes in a population of
    organisms
  • Changes eh?
  • Allelic frequency changes within a
  • gene pool!

4

5
WHAT LEADS TO CHANGES IN THE GENE POOL OF A
POPULATION?
  • SMALL POPULATION SIZE
  • (small pop ? frequencies)
  • toss a coin to prove it.

6
MECHANISMS OF EVOLUTION
  • GENETIC DRIFT
  • (random/chance events that change the gene pool
    of a small population)
  • examples
  • natural disasters

7
2 TYPES OF GENETIC DRIFT MECHANISMS
  • Genetic Bottleneck
  • dramatic decrease in pop size due to
  • catastrophes
  • predation
  • disease, etc.

8
(No Transcript)
9
(No Transcript)
10
  • Founder Effect
  • migration leads to changes in allele
  • frequencies from population of origin

11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
WHAT ELSE CAUSES GENE POOL CHANGES ?
  • GENE FLOW
  • immigration
  • emigration

15
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

16
  • MUTATIONS
  • may produce a selective advantage
  • may produce deleterious effects
  • may be harmless

17
  • NATURAL SELECTION!
  • increases/decreases allele frequencies due to
    environmental impact.
  • Ex English Peppered Moths

18
  • NON-RANDOM MATING
  • individuals choose based upon traits
  • (vertebrates)
  • individuals choose based upon
  • physical proximity
  • (invertebrates)

19
OTHER FORMS OF NON-RANDOM MATING
  • INBREEDING
  • Proximity issues
  • SEXUAL SELECTION
  • Male competition
  • offspring ? fitness
  • Female choice
  • quality offspring ? fitness

20
SEXUAL SELECTION
  • Picky females, show-off males

21
MICROEVOLUTION REVIEW
  • Changes in the GENE POOL!
  • Caused by
  • Gene Flow
  • Natural Selection
  • Mutations
  • Non-Random Mating
  • Sexual Selection
  • Inbreeding

22
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

23
SUBDIVISIONS OF NATURAL SELECTION
  • Stabilizing Selection
  • Eliminates individuals with extreme traits.
    Results in decreased variation

24
  • Directional Selection
  • Favors traits at ONE extreme
  • ex resistance to insecticides

25
DIRECTIONAL SELECTION
26
  • Disruptive Selection
  • Selection toward BOTH extremes. Extreme traits
    are favored, common traits are NOT!
  • Results in major divisions in population!
  • What might result?

27
DISRUPTIVE SELECTION
28
ARTIFICIAL SELECTION
  • Directional selection determined by humans

29
(No Transcript)
30
CAUSES OF VARIATION
  • Mutation is the ultimate source of variation
  • Two major types of mutations
  • Gene mutations
  • Chromosome mutations

31
GENE MUTATIONS
  • Addition / Insertion
  • Deletion
  • Substitution
  • Inversion

32
(No Transcript)
33
SPECIFIC EXAMPLES OF MUTATIONS
  • Gene mutations
  • PKU (phenylketonuria)
  • CF (cystic fibrosis)
  • Chromosome mutation
  • Klinefelter syndrome (male with 47,XXY karyotype)

34
ONCE MUTATIONS HAVE ARISEN, FURTHER VARIATION
RESULTS FROM
  • Recombination of alleles during meiosis
  • Recombination of alleles during fertilization

35
ONCE GENETIC VARIATION HAS ARISEN, THERE IS ALSO
PHENOTYPIC VARIATION.
  • Recall that, according to Darwins Theory, due to
    competition within populations, there is
  • Differential Reproduction of Selected Phenotypes

36
GREAT EXAMPLE OF DIFFERENTIAL REPRODUCTION OF
SELECTED PHENOTYPES
37
ULTIMATE RESULT OF EVOLUTION
  • Change in the genetic composition (gene pool) of
    a population.

38
RELATED CAUSES OF GENETIC VARIATION
  • Sexual Reproduction!
  • Diploidy
  • Outbreeding

39
MINORITY ADVANTAGE
  • 50/50 Sex Ratio
  • Predation (more common phenotype preferred by
    predator)
  • The Lefty Hypothesis
  • 10-15 general population
  • gt50 contact sports (esp. males)

40
REPRODUCTIVE ISOLATION
  • Prezygotic
  • Temporal isolation
  • Behavioral isolation
  • Mechanical isolation
  • Ecological isolation
  • Gametic isolation
  • Postzygotic
  • Hybrid inviability
  • Hybrid sterility
  • Hybrid breakdown

41
ALLOPATRIC SPECIATION
42
SYMPATRIC SPECIATION
43
GRADUALISM
  • Species A evolves to become species B.
  • LONG, GRADUAL process!

44
PUNCTUATED EQUILIBRIUM
  • Evolution is Slow with brief periods of rapid
    development of new species.

45
(No Transcript)
46
THE HARDY WEINBERG LAW
  • If allele frequencies for a population do not
    change
  • NO EVOLUTION IS OCCURRING!
  • Genetic Equilibrium
  • Hardy Weinberg Equilibrium

47
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

48
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

49
(No Transcript)
50
(No Transcript)
51
(No Transcript)
52
IS HW EQUILIBRIUM POSSIBLE?
  • YES ? / NO ?
  • WHY / WHY NOT??

53
  • http//zoology.okstate.edu/zoo_lrc/biol1114/tutori
    als/Flash/life4e_15-6-OSU.swf

54
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

55
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

56
  • If pq1,
  • then (pq)2 1.
  • Expand it and get
  • p 2 2pq q2 1

57
WHAT DOES IT ALL MEAN GENOTYPICALLY?
  • p2 frequency of AA
  • 2pq frequency of Aa
  • q2 frequency of aa

58
PROBLEM 1
  • In pigs, the allele for black coat (b) is
    recessive to the allele for pink coat (B).

59
WHAT OF PIGS ARE HETEROZYGOUS FOR PINK COAT?
60
PROBLEM 2
61
PROBLEM 3
62
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?
About PowerShow.com