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Charles Robert Darwin 18091882

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Title: Charles Robert Darwin 18091882


1
Charles Robert Darwin (1809-1882)
2
Charles Darwin and the Voyage of the Beagle
3
Charles Darwin and the Voyage of the Beagle
4
Charles Darwin and the Voyage of the Beagle
5
Charles Darwin and the Voyage of the Beagle
  • During the voyage, Darwin...
  • was perennially seasick
  • read Lyells Principles of Geology
  • spent lots of time ashore in South America and
    other locations
  • observed and collected a large number of fossils,
    plants, and animals
  • What Darwin Saw...
  • an earthquake that changed the level of the land
    dramatically in Concepcion, Chile
  • fossils of marine shells at 14,000 feet in the
    Andes
  • patterns of geographic distribution of plants and
    animals that suggested the importance of
    geographic isolation in the formation of
    species...

6
Charles Darwin and the Voyage of the Beagle
  • What Darwin Saw
  • Plants and animals in the New World tropics are
    like those in the New World temperate zone, not
    like those in the Old World tropics.
  • Extant South American plants and animals are like
    extinct South American plants and animals, not
    like extant plants and animals elsewhere.
  • Extant mammals in Australia are not like mammals
    anywhere else.
  • Animals (and plants) on oceanic islands are like
    those of the nearest continent, not like those on
    other oceanic islands elsewhere.
  • Animals on islands near each other in
    archipelagoes are distinct but similar.

7
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8
Charles Darwin and Natural Selection
  • Darwin wrote two essays, the first in 1842, and
    an expanded version in 1844
  • The 1844 essay (it was 240 pages) contains a
    complete, detailed, and well documented argument
    for how the process of natural selection acts to
    produce adaptation or design in organic beings
  • Darwin knew what he had done, and showed none but
    his wife and a few close colleagues his essay...

9
Darwin in 1854
10
Charles Darwin and Natural Selection
  • We see these beautiful co-adaptations most
    plainly in the woodpecker and misseltoe and only
    a little less plainly in the humblest parasite
    that clings to the hairs of a quadruped or the
    feathers of a bird in the structure of the
    beetle which dives through the water in the
    plumed seed which is wafted by the gentlest
    breeze in short, we see beautiful adaptations
    everywhere Darwin, 1859

11
Charles Darwin and Natural Selection
  • "How have all those exquisite adaptations of one
    part of the organisation to another part, and to
    the conditions of life, and of one distinct
    organic being to another being, been perfected?"
    Darwin, 1859

12
Charles Darwin and Natural Selection
  • Ernst Mayr (1904-2004)
  • Eminent naturalist
  • Architect of the new synthesis
  • Analyzed Darwins argument in On the Origin of
    Species
  • A Mayr quote Being a biologist is such great
    fun!

13
Natural Selection
  • Fact 1 Many more organisms are produced through
    reproduction than can survive (geometric
    increase, biotic potential)
  • The principle of Malthus

14
Natural Selection
  • Fact 1 Many more organisms are produced through
    reproduction than can survive (geometric
    increase, biotic potential)
  • Cockroaches, rabbits, cattails
  • Elephants
  • People?

15
Natural Selection
  • Fact 1 Many more organisms are produced through
    reproduction than can survive
  • Fact 2 Population sizes of most species are
    stable on a seasonal and annual basis (in spite
    of biotic potential, population sizes do not
    increase)

16
Natural Selection
  • Fact 1 Many more organisms are produced through
    reproduction than can survive
  • Fact 2 Population sizes of most species are
    stable on a seasonal and annual basis
  • Fact 3 Natural checks on increase

17
Natural Selection
  • Fact 1 Many more organisms are produced through
    reproduction than can survive
  • Fact 2 Population sizes of most species are
    stable on a seasonal and annual basis
  • Fact 3 Natural checks on increase limitation
    of resources, predation, abiotic conditions

18
Natural Selection
  • Fact 1 Many more organisms are produced through
    reproduction than can survive
  • Fact 2 Population sizes of most species are
    stable on a seasonal and annual basis
  • Fact 3 Natural checks on increase
  • Inference 1 A struggle for existence

19
Natural Selection
  • Two canine animals in a time of dearth, may be
    truly said to struggle with each other which
    shall get food and live. But a plant on the edge
    of the desert is said to struggle for life
    against the drought The misseltoe is dependent
    on apple and other trees, but can only in a
    far-fetched sense be said to struggle with these
    trees... Darwin, 1859

20
Natural Selection
  • I use the term Struggle for Existence in a
    large and metaphorical sense, including
    dependence of one being on another, and
    includingnot only the life of the individual,
    but success in leaving progeny. Darwin, 1859

21
Natural Selection
  • Fact 4 Variation in characteristics among
    individuals within populations of organic beings

22
Natural Selection
The granite grasshopper, Trimerotropis saxatilis
23
Natural Selection
  • Fact 4 Variation
  • Fact 5 Heritability - characteristics are passed
    from parents to offspring

24
Natural Selection
  • Fact 4 Variation
  • Fact 5 Heritability

25
Natural Selection
  • Fact 4 Variation
  • Fact 5 Heritability

26
Natural Selection
Francis Crick and James Watson elucidate the
structure of DNA - 1953
27
Natural Selection
  • Fact 4 Variation
  • Fact 5 Heritability
  • Inference 2 Differential Reproductive Success -
    because of their characteristics, some
    individuals are more likely to survive and
    produce offspring than others
  • Can we doubt... that individuals having any
    advantage, however slight, over others, would
    have the best chance of surviving and procreating
    their kind? Darwin, 1859

28
Natural Selection
Stenaspis verticalis
Plectrodera scalator
29
Natural Selection
  • Fact 4 Variation
  • Fact 5 Heritability
  • Inference 2 Differential Reproductive Success
  • Inference 3 Successful characteristics (those
    that promote individual survival and reproductive
    success) become more prevalent in the population
    (the characteristics of the population are
    modified through descent)

30
Natural Selection
  • Fact 4 Variation
  • Fact 5 Heritability
  • Inference 2 Differential Reproductive Success
  • Inference 3 Successful characteristics become
    more prevalent in the population
  • Darwin's conclusion Over time, various changes
    accumulate in populations, leading to well
    adapted or designed organisms

31
Natural Selection
  • Individuals differ in various phenotypic
    characteristics
  • Phenotypic characteristics of individuals can be
    passed to their offspring
  • Some individuals produce more offspring than
    others (because of their characteristics)
  • Phenotypic characteristics that confer greater
    reproductive success become more prevalent in the
    population
  • Changes accumulate in the population over time
  • Accumulated changes in characteristics lead to
    better designed or adapted organisms

32
Natural SelectionThe Darwinian Mantra
  • Variation
  • Heritability
  • Differential Reproductive success
  • Spread of traits through the population
  • Accumulation of change over time
  • Changes in characteristics lead to better
    designed or adapted organisms

33
Natural SelectionThe Darwinian Mantra
  • Heritable variation combined with differential
    reproductive success leads to the spread of
    traits through populations, which leads to
    adaptation.

34
Natural Selection
  • Survival of the fittest?

35
Natural Selection
  • Survival of the fittest?

36
Natural Selection
  • Survival of the fittest?

37
Types of evolutionary change
  • Anagenesis
  • AKA Microevolution
  • adaptive change within species
  • descent with modification
  • Cladogenesis
  • AKA Macroevolution
  • derivation of new species from previously
    existing ones
  • transmutation of species

38
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39
Natural Selection in Actionindustrial melanism
Biston betularia, the Peppered moth Typical form
Biston betularia, the Peppered moth Melanic form
40
Natural Selection in ActionBiston betularia
A mark-recapture experiment marked melanic and
typical moths were released onto polluted and
clean tree trunks, then recaptured later. The
data ( recaptured) polluted trees clean
trees melanics 34.1 6.3 typicals 16.0 12.
5
41
Natural Selection in ActionBiston betularia
Direct observations of predation melanic and
typical moths were placed onto polluted and clean
tree trunks, then observed from a blind. The
data ( attacked by birds) polluted
trees clean trees melanics 26 86 typicals 7
4 14
42
Natural Selection in ActionBiston betularia
  • Criticisms of the industrial melanismstory
  • Melanism is environmentally induced
  • It can be, but
  • Moths dont actually rest by day on tree trunks
  • They do, but not exclusively
  • Kettlewell glued his moths to the tree trunks
  • What else was he to do?

43
Natural Selection in ActionBiston betularia
  • Criticisms of the industrial melanismstory
  • Changes in frequency of melanics and typicals
    doesnt match changes in lichen cover of tree
    trunks
  • In Great Britain
  • In the US
  • The bottom line on Industrial Melanism

44
Natural Selection in ActionDarwins finches
From Sato, A. et al, 1999. Phylogeny of Darwin's
finchesPNAS 96 5101-5106
45
Natural Selection in ActionDarwins finches
From Grant, P. 1991. Natural selection and
Darwin's Finches. Scientific American
46
Natural Selection in Action
47
Natural Selection in Action
48
Natural Selection in Action
49
Natural Selection in Action
50
Natural Selection in Action
51
Natural Selection in Action
52
Natural Selection in Action -human birth weight
53
Natural Selection in Action
54
Natural Selection in Action
55
Natural Selection in Action
disruptive selection
56
Natural Selection in Action - disruptive
selection
57
Natural Selection in Action - disruptive
selection
58
Natural Selection in Action - disruptive
selection
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