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Biology 2900 Principles of Evolution and Systematics

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Links to Evolution Web Pages. Midterm Test: Thursday, Feb. 15, 2007. Goals ... Two phenotypes: white, yellow. Natural Selection ... – PowerPoint PPT presentation

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Title: Biology 2900 Principles of Evolution and Systematics


1
Biology 2900Principles of Evolutionand
Systematics
  • Dr. David Innes
  • Dr. Ted Miller
  • Jennifer Gosse
  • Valerie Power

2
  • Lecture Tues. Thurs 1030 - 1145 am
  • IIC-2001
  • Laboratory Mon Tues Wed Thr 200 - 500 pm
  • SN-4110
  • Labs. Week of January 8 12
  • Organization of groups
  • Group 1 Lab. Week of Jan. 15
  • Download handout
  • http//www.mun.ca/biology/dinnes/B2900/B29
    00.html

3
  • Text Evolution
  • Douglas J. Futuyma (2005)

  • http//life.bio.sunysb.edu/ee/people/futuyindex.ht
    ml

4
Course Web Site
  • http//www.mun.ca/biology/dinnes/B2900/B2900.htm
    l
  • Course outline
  • Lecture slides (pdf file)
  • Information, readings etc.
  • Links to Evolution Web Pages
  • Midterm Test Thursday, Feb. 15, 2007

5
Goals
  • Ask interesting questions about evolution
  • Experiments and observations to answer ??
  • Critically evaluate primary literature
  • Contribute to the discussion of evolution between
    specialists and public
  • Think like evolutionary biologists !!!!

6
Evolution Thinking
  • Why do organisms age and die ?
  • What do fossils tell us about the evolutionary
    history of animals?
  • Why do some male spider sacrifice themselves
    during mating?

7
Example
Sex and death in the Australian red-back spider
Sexual cannibalism How could
evolution have produced a behavior that reduces
the chance of survival ? (Research of
Dr. Andrade, U. of T.)
male
male
8
Experimental Results
  • Cannibalized males copulated longer and
    fertilized more eggs than those that survived
    copulation
  • Females were more likely to reject subsequent
    suitors after consuming their first mate
  • Empirical evidence for male copulatory
  • suicide as an adaptive behavior

9
Olivia Judson
10
  • Evolution
  • a change in the properties of groups of
    organisms over the course of generations (ie.
    time) (Futuyma, 2005)

11
  • current life forms differ from those of previous
    times and yet are descended from them
  • Descent with modification

12
  • The study of Evolution
  • - how populations change in response to their
    environment
  • - formation of new species
  • The Study of Adaptation and Diversity

13
  • Special Creation
  • 1. Species created independently
  • 2. Species do not change
  • 3. Species created recently
  • (within 6,000 years)

14
  • The Fact of Evolution
  • Charles Darwin (1809 - 1882)
  • - English Naturalist
  • - HMS Beagle (Galapagos Islands)
  • - 1859 Origin of Species

15
HMS Beagle 1831 - 1836
http//www.literature.org/authors/darwin-charles/t
he-voyage-of-the-beagle/
16
1859
Origin of Species online http//www.literature.or
g/authors/darwin-charles/the-origin-of-species/
17
  • The Fact of Evolution
  • - evidence from biology and geology
  • - species had changed through time
  • - descended with modification from common
    ancestors

18
  • The Fact of Evolution
  • Evidence
  • 1. relatedness of life forms
  • 2. change through time
  • 3. age of the earth

19
  • 1. Relatedness of Life Forms
  • A. Comparative anatomy
  • - homology similar structure (bones)
  • - shared ancestry
  • B. Galapagos Islands
  • - distinct but related species
  • - shared ancestry

20
  • Relatedness of life forms
  • (Vertebrate limb)

HOMOLOGY similar structure, different function
21
  • Relatedness of life forms

Molecular conserved structure and function
Cytochrome c Cellular respiration 3D structure
based on amino acid sequence
Tuna fish
Rice
22
  • Relatedness of life forms
  • Phylogenetic tree
  • tips descendant
  • branches
  • nodes ancestor

taxa
A
B
C
D
Time
Common ancestor
Divergence
23
Phylogenetic Trees
Fig. 2.10
Fig. 2.2
Darwin 1859
Some vertebrates
24
2. Change Through Time
  • Fossil and living - related but different
  • Island colonists vs. mainland
  • Vestigial structures (eyes, bones)
  • Extinction, marine fossils in nonmarine areas
  • Change in landforms, habitats and species

25
2. Change Through Time
Loss of eyes
  • Vestigial structures

26
  • 3. Age of the Earth
  • - Geology processes work very slowly
  • - Present-day formations required very long
  • periods of time to
    produce
  • therefore, the earth must be very old
  • Biological evolution has occurred over a very
    long period of time

27
Age of the Earth
  • Geological Time Scale
  • - younger rock on top of older rocks
  • - earlier fossil life forms simpler
  • - more recent fossils similar to existing
  • forms
  • Radiometric dating 4.6 billion years

28
Age of the Earth
10,000 years per page
29
Age of Rocks
30
Precambrian Rocks 4.5 billion 560 million
years ago
31
  • The Fact of Evolution
  • Evidence
  • 1. relatedness of life forms
  • 2. change through time
  • 3. age of the earth

32
Darwin
  • One of the most revolutionary ideas in the
    history of science
  • All organic beings which have ever lived on this
    earth have descended from some one primordial
    form

33
The Fact of Evolution
  • A scientific theory is a mature, coherent body
    of interconnected statements, based on reasoning
    and evidence, that explains a variety of
    observations
  • The fact of evolution is explained by
    evolutionary theory

Futuyma, 2005
34
  • The study of Evolution
  • (Adaptation and Diversity)
  • Where do living things come from ?
  • Why are there so many different kinds of
    organisms ?
  • How have organisms adapted so well to their
    environment ?

35
  • Darwin (Origin of Species)
  • Existing species are the modified descendants of
    forms that existed previously
  • (descended from common ancestors)
  • But how ? ?Natural Selection
  • Theory by C. R. Darwin and A. R. Wallace

36
Artificial Selection
  • The mechanism of evolution under domestication
  • 1. Phenotypic Variation
  • 2. Variation heritable
  • 3. Selective breeding (non-random
  • survival and reproduction)

C. Darwin (1968) The variation of animals and
plants under domestication
37
Cabbage
Brassica oleracea
Wild Cabbage
Kale
38
Pigeons
39
Dogs
40
Domestic Cats
41
Natural Selection
  • Darwin realized that a process much like
    artificial selection happens in nature
  • Why did it take so long to realize a connection
    between the power of artificial selection and the
    potential of natural selection for evolution?

42
Phenotypic Variation in Natural Populations
  • Phenotypic Variation among individuals within a
    wild species much more subtle

43
Phenotypic Variation in Natural Populations
44
Natural Selection
  • The Theory of Evolution by Natural Selection
    proposes that evolution is the logical outcome of
    4 postulates

45
Evolution by Natural Selection
  • 1. Individuals within populations variable (Lab
    1)
  • 2. Some variations inherited by offspring
  • 3. Some individuals more successful at surviving
    and reproducing than others
  • 4. Survival and reproduction not random tied to
    the variation among individuals

46
  • Individuals within populations variable
  • - observed phenotypic variation
  • 2. Some variations inherited by offspring
  • - offspring resemble parents
    (mechanism?)

Evolution by Natural Selection
47
Evolution by Natural Selection
  • 3. Some individuals more successful at surviving
    and reproducing than others
  • - enormous reproductive potential
  • Aphid ?
    524 billion/yr
  • House fly ?
    191 x 1018 in 5 months
  • Thomas Malthus' Essays on
    Population
  • http//personal.clt.bellsouth.net/t/a/tarab
    yl/malthus.htm

48
Evolution by Natural Selection
  • 4. Survival and reproduction not random tied to
    the variation among individuals

Two phenotypes white, yellow
49
Natural Selection
  • If the 4 postulates true, then the composition of
    the population changes from one generation to the
    next
  • Natural Selection produces decent with
    modification (Evolution)

50
  • Fitness
  • Ability of an individual to survive and reproduce
    in its environment
  • Adaptation
  • Traits that increase fitness relative to
    individuals without the traits

51
  • Implications and consequences of NS
  • -natural mechanism for evolution
  • -descent from common ancestor ? order
  • -natural classification ? hierarchical
  • -all living things related ? phylogeny
  • -humans evolved
  • Darwin-Wallace Theory of NS testable

52
  • Can natural selection lead to evolutionary change
    ?
  • Model systems to test natural selection
  • Galapagos Finches - P. R. Grant

53
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54
Galapagos Islands
55
  • Galapagos Finches
  • - 13 closely related species
  • differ in beak morphology
  • Variation associated with food eaten

56
Geospiza fortis
57
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58
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59
  • Test of 4 postulates
  • Geospiza fortis on the island of
  • Daphne major
  • 1. Are populations variable ?
  • 2. Variation heritable ?
  • 3. Only some offspring live to reproduce ?
  • 4. Survival and reproduction nonrandom ?

60
  • Variation in Bill Depth

61
Heritability of Bill Depth
Fig 9.20
Offspring Bill Depth (mm)
1978 1976
VP VG VE H2 VG / VP 0.90
Midparent Bill Depth (mm)
62
Seed abundance
Pop. Size
Large Hard
Seeds
  • decreased survival and reproduction
  • Was survival and reproduction nonrandom with
    respect to bill size ?

Small Soft
1977 drought
63
Before
After
Beak Depth (mm)
64
Natural Selection
  • Large amount of variation in bill depth
    (phenotypic)
  • Much of variation heritable (genetic)
  • Drought resulted in decreased survival and
    reproduction
  • (due to change in food resource)
  • - only some individuals survived and
    reproduced
  • Survival and reproduction non-random with
    respect to bill
  • depth (birds with larger bills
    favoured)

65
Natural Selection
  • Finches with a larger, deeper bill had an
  • advantage (directional selection)
  • Drought resulted in only larger, harder seeds
  • Wet years abundant small, soft seed
  • smaller bills favoured
  • Natural Selection is Dynamic

66
Beak Size
Natural Selection Dynamic 30 years of data
Beak Shape
95 CI for 1973 data
Body Size
67
  • Features of Natural Selection
  • 1. Acts on indiv., consequences in pop.
  • 2. Evolution consists of changes in gene
    frequencies

Gen. 1
Gen. 2
Heritability 0
Heritability gt 0
68
  • Features of Natural Selection
  • 3. NS not forward looking
  • 4. NS acts on existing traits
  • 5. NS directed, not random
  • 6. Fitness not circular (Survival of the
    fittest)
  • 7. NS acts on individuals not groups

69
  • Features of Natural Selection
  • Components of fitness
  • - survival
  • - reproduction
  • More offspring produced than can survive
  • (Potential for exponential population growth)

70
Natural Selection
  • molecular/morphological change over
  • very short time intervals
  • small changes
  • can small changes over short time
  • intervals lead to larger changes over
  • longer time intervals ?

71
  • Changes
  • Microevolution to Macroevolution
  • Requires very long periods of time

72
  • Age of the Earth
  • - about 4.6 billion years ago
  • - first evidence of life 3.8 billion years ago
  • - over long periods of time, small changes become
    large

Fig. 3.12 60 year corn oil selection experiment
73
  • New Species
  • - Physical isolation (dispersal and colonization)
  • - Divergent natural selection (diff.
    environments)
  • Natural selection can explain - adaptation

  • - diversity

74
  • Problems that concerned Darwin
  • 1. Source of variation ? mutation
  • 2. Inheritance ? Mendel
  • 3. Age of the earth ? radioisotopes

75
  • Modern Synthesis
  • Synthesis of variability, inheritance and time
  • 1932 - 1953
  • - botany, systematics, population genetics,
    paleontology

76
Evolution by Natural Selection
  • Complexity in nature
  • - how random changes can lead to order ?
  • - how can complex structures evolve through the
    gradual accumulation of small changes ?

77
  • The Eye Evolution of a Complex Structure
  • - each step had to increase fitness
  • - are there diverse forms of eyes, some more
    complex than others ?

78
Mollusc Eyes
Pigment spot
Pigment cup
abalone
octopus
Marine snail
79
Evolution by Natural Selection
  • Observed diversity of life
  • Organisms adapted to their environment
  • The fact of evolution
  • NS a mechanism for explaining
  • observations
  • Natural Selection in Humans ?
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