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EVOLUTION: Unifying Concept in Biology

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Title: EVOLUTION: Unifying Concept in Biology Author: Carol Eunmi Lee Last modified by: Carol Eunmi Lee Created Date: 1/18/2014 3:12:29 AM Document presentation format – PowerPoint PPT presentation

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Title: EVOLUTION: Unifying Concept in Biology


1
On your Notecards please write the following
(1) Name (2) Year (3) Major (4) Courses taken in
Biology (4) Career goals (5) Email address (6)
Why am I taking this class?
2
EVOLUTION
The Unifying Concept in Biology
Dr. Carol Eunmi Lee University of Wisconsin,
Madison
3
Theodosius Dobzhansky (1900-1975)
Nothing in biology makes sense except in the
light of evolution
4
Reading
(1) Evolutionary Analysis 5th Edition,
2013 Jon Herron Scott Freeman
(2) Journal articles posted on Course Website
5
Course Website
  • https//mywebspace.wisc.edu/carollee/web/Lee/Evolu
    tion410.html

6
Background needed for this course
  • Some understanding of basic genetics (Hardy
    Weinberg Equilibrium, DNA, RNA, transcription,
    translation, allele, genotype)

7
OUTLINE
  • 1) Overview
  • 2) What is Evolution?
  • 3) Basic Concepts
  • 3) Practical Applications
  • 4) Example of Evolution in Action Evolution of
    HIV

8
Course Overview
  • (1) TODAY What is Evolution? Practical
    Applications
  • (2, 3) History of Evolutionary Thought
  • (4) Hardy Weinberg Equilibrium (no evolution),
    Genetic Drift
  • (5) EVOLUTIONARY MECHANISMS Genetic Drift
  • (6, 7) EVOLUTIONARY MECHANISMS Genetic Variation
  • (8) EVOLUTIONARY MECHANISMS Epigenetic
    Inheritance
  • (9,10) EVOLUTIONARY MECHANISMS Natural Selection
  • (11, 12) Molecular Evolution
  • (13, 14) Genome Evolution
  • (15, 16) Evolutionary Tradeoffs
  • (17, 18) Speciation
  • (19, 20) Earth History, History of Life on Earth
  • (21, 22) Reconstructing the Tree of Life
  • (23) Microbial Evolution
  • (24) Plant Evolution
  • (25, 26) Animal Diversity
  • (27, 28) Human Evolution

9
Structure of Lectures
  • Introduction What is Evolution? Practical
    Applications
  • Background History of Evolutionary Thought
  • No Evolution Hardy Weinberg Equilibrium
  • Evolutionary Genetic Drift
  • Mechanisms Genetic Variation (Mutation,
    Recombination)
  • Epigenetic Variation
  • Natural Selection
  • (including molecular and genome levels)
  • Macroevolution Speciation
  • History of Life on Earth
  • Tree of Life
  • Diversity Microbial Evolution
  • Plant Evolution
  • Animal Diversity
  • Human Evolution

10
Grading Exams
  • 3 exams of equal weight, multiple choice 100
    points each 300 pts total
  • 3 quizzes 20 points each 60 pts total
  • 3 homeworks 30 points each 90 pts total
  • In-class extra credit, unannounced random
    dates 50 pts

300 (exams) 60 (quizzes) 90 pts (homework)
50 pts (extra credit) 500 points total
11
Q What is Evolution?Q How does Evolution
Occur?
12
Q1 What is Evolution?
13
Q1 What is Evolution?(give the most
comprehensive answer)
  1. The increase in fitness over time due to natural
    selection, or adaptation.
  2. The accumulation of mutations, which alter
    fitness over time.
  3. The change in allele frequencies (or the
    heritable expression of those alleles) in a
    population across generations.
  4. The progression into more complex forms of life

14
Q1 What is Evolution?(give the most
comprehensive answer)
  • The change in allele frequencies (or the
    heritable expression of those alleles) in a
    population across generations.
  • (BB) (Bb) (bb)
  • Blue Purple Red
  •  
  • Generation 1 250 500 250
  • Generation 2 200 600 200
  • Generation 3 100 800 100

Although, even if allele frequencies in a
population remain the same across generations, a
population is evolving if it goes out of
Hardy-Weinberg Equilibrium (more on this later)
15
Q What is Evolution?
  • Change in proportions of genetically different
    individuals at each generation
  • Leading to an average change in characteristics
    of populations over time ? change in allele
    frequencies (genetic composition) or the
    heritable change in the expression of those
    alleles (epigenetic inheritance)
  • Acts by removing individuals from the population,
    or by allowing some to leave more offspring
  • By population, we are referring to a group of
    interbreeding individuals and their offspring (in
    the case of sexual species)

16
Q3 How does Evolution Occur?
17
Q3 How does Evolution Occur?
  • Through 5 Major Mechanisms
  • Genetic Drift
  • Mutation
  • Heritable Epigenetic Modification
  • Migration
  • Natural Selection
  • (Think about what forces would change the allele
    frequencies in a population, or the heritable
    expression of those alleles)

18
i.e. what causes changes in the allelic
composition in a population?
  • Genetic Drift totally random changes in allele
    frequency from generation to generation
  • Mutation changes in the genetic code, such as
    errors in DNA replication, gene deletions or
    duplications, etc
  • Epigenetic Inheritance heritable changes that
    are not due to changes in DNA sequence itself,
    but the expression of the DNA, such as changes in
    DNA methylation and histone modifications, etc
  • Migration alleles moving from one population to
    another
  • Natural Selection when some alleles favored
    over others due to an increase in fitness (not
    random) acts on genetic variation in the
    population

19
Sources of Genetic Variation
Mutation generates genetic variation Epigenetic
modification changes expression of genes
Genetic Drift reduces genetic variation
Natural Selection
Natural Selection acts on genetic or epigenetic
variation in a population
Without genetic or epigenetic variation, Natural
Selection cannot occur
20
Evolutionary Concepts Permeate all Aspects of
Biology
  • Biotechnology
  • Agriculture
  • Medicine
  • Conservation

21
Agriculture
  • Most of your food is a product of intense
    artificial selection, or human induced evolution

22
Evolution of a Pathogen as an Example
  • I will now use an infectious disease to
    illustrate basic evolutionary concepts.
  • The following example illustrates several
    evolutionary mechanisms
  • I will explain these concepts in more detail over
    the next few lectures

23
HIV infects macrophages, T-cells
HIV Fastest evolving organism on Earth
24
AIDS Pandemic
  • AIDS is among the most deadly epidemics in Human
    History (1981-2009 30 million deaths)
  • 34 million people living with AIDS (estimated
    2010)
  • 90 million deaths predicted by 2020

people living with HIV
UNAIDS. 2008 Report on the Global AIDS
Epidemic (http//www.unaids.org/en/KnowledgeCentr
e/HIVData/GlobalReport/2008/)
25
A global view of HIV infection 33 million people
3036 million living with HIV, 2007
26
Problem
  • HIV has the fastest mutation rate of any virus or
    organism observed to date
  • HIV evolves more rapidly than humans, and more
    quickly than the ability of humans to produce new
    drugs
  • Implications AIDS vaccines are unlikely to work
    on all strains of the virus and unlikely to
    work on a given strain in the long run
  • Our understanding of how to combat viruses had in
    general been poor, and the recent intensive
    research on HIV has greatly enhanced our
    understanding of how to combat viruses in general

27
Questions
(1) What is Evolution? (2) How does evolution
operate? What are the main Evolutionary
Mechanisms? (3) Discuss how an understanding of
evolution impacts practices in Agriculture,
Medicine, and Conservation (4) For example,
discuss how different evolutionary mechanisms
impact the evolution of HIV, the virus that
causes AIDS
28
Concepts
Evolution Population Genetic Drift Natural
Selection Mutation Genetic Variation Allele,
Genotype HIV
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