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Evolution

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Evolution Geology 103 ... 1859) publishes his theory of organic evolution based on observations he had made on the voyage of the Beagle and other work. – PowerPoint PPT presentation

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Title: Evolution


1
Evolution
  • Geology 103

2
Fossil classification
  • Body fossils actual representation of the
    organism preserved in the rock also includes
    molds and casts
  • Trace fossils evidence of the passage of an
    organism includes burrows, borings and tracks

3
Body fossil preservation
  • Permineralization  Dissolved minerals
    precipitate in cavities within organism

4
Body fossil preservation
  • Replacement Dissolved minerals precipitate as
    organisms original materials dissolve

5
Body fossil preservation
  • Carbonization Organisms tissues are compressed
    and lose their volatile components, leaving
    behind a carbon film

6
The key to good preservation
  • Bury the organism quickly (anoxic conditions).
  • Dont disturb it for a long time. This includes
    plate tectonics.

7
Fossils
  • Latin Dug up
  • Represent any indication of past life
  • Posed an issue for early geologists
  • Some believed that fossils were rocks trying to
    become living organisms
  • Aristotle to DaVinci agreed that they were
    remains of past life

8
Neptunism
  • School of thought about the origin of rocks that
    arose in the late 18th century
  • Held that the world was inundated in a great
    flood (or floods) that deposited every single
    rock
  • Abraham Werner (Freiburg School of Mining, 1750
     1817)

9
Plutonism
  • Werner believed that the heat source for
    volcanoes and other eruptive features were
    burning coal beds
  • Others, notably James Hutton (University of
    Edinburgh, 1726  1797), argued for magma as the
    source for volcanoes
  • Culminated in debate over the origin of granite
  • Hutton also known for his quote that in the rock
    record we find no vestige of a beginning, no
    prospect of an end

10
Catastrophism
  • Baron Georges Cuvier (Museum of Natural History,
    Paris,1769-1832) was the main proponent
  • Earth is immensely old but has recurring
    revolutions that result in extinctions of
    organisms

11
Faunal succession
Faunal succession is not evolution because faunal
succession makes no claims as to the connections
between organisms found in different layers.
12
How do organisms change over time?
  • Jean-Baptiste Lamarck (Museum of Natural History,
    Paris, 1744  1829) suggested that changes in the
    environment caused changes in behavior of
    organisms that resulted in physical changes in
    those organisms that could be inherited by
    offspring

13
First, we need to organize life
  • Carl Linnaeus (University of Leiden, 1735)
    publishes Systema Naturae, which categorized much
    of what was being discovered of life on different
    continents

14
Traditionally, the Linnean classification system
used anatomical differences to organize organisms
15
Uniformitarianism
  • Key to the past is the present
  • Charles Lyell (1830) publishes Principles of
    Geology in which he advocates slow, gradual
    changes in Earth processes, implying an immense
    amount of time had already passed

16
On the Origin of Species
  • Charles Darwin (Geological Society of London,
    1859) publishes his theory of organic evolution
    based on observations he had made on the voyage
    of the Beagle and other work.
  • Check out my colleage Rob Viens daily
    re-creation of the voyage http//beagleproject.wo
    rdpress.com/tag/voyage-of-the-beagle/

17
The three tenets of Darwinian evolutionary theory
  • There exists a group of organisms (population)
    that mate and reproduce fertile offspring
    (species)
  • Natural selection favors one variation over
    another
  • The favored variation survives to produce more
    offspring than unfavored variations

18
One method of speciation
  • Allopatric speciation suggests that
    geographically isolated populations may, through
    genetic drift, become distinct species over time
  • Darwins finches

19
Adaptive radiation
  • Rapid speciation may occur when extinction
    vacates a lot of environmental niches.

20
Punctuated equilibrium
  • In fact, we have been modifying Darwins theory
  • In 1972, Neals Eldrege and Stephen Jay Gould
    (Harvard) proposed that evolution of organism
    occurs relatively rapidly during periods of
    environmental stress, and that most species stay
    static otherwise

21
Ideally, in the rock record...
  • One would see a succession of evolved forms of
    the same type in successive layers

22
But, in the real world,....
  • Unconformities may remove the evidence of
    transitional species
  • Also, sometimes hard to tell apart from rapid
    speciation.

23
Cladistics the science of organizing organisms
by evolutionary history
24
Cladistics the science of organizing organisms
by evolutionary history
25
Cladistics are based on shared evolutionary
history
  • This can be traced in many ways for instance,
    the traditional anatomical methods or (more
    recently) DNA analysis

26
How to tell clades from non-clades
  • Recall that a clade is a group of organisms that
    all share a common trait

27
Now most clades dont change much over time
  • This is because most organisms do not need to
    rapidly adapt or speciate during times of
    environmental stability

28
Cladistics leads to some interesting results
No such clade as reptiles
Dinosaurs arent extinct
29
And we arent that closely related to chimps
anyway
  • Cladistics can reveal the evolutionary history of
    even closely-related organisms

30
Clades over time
  • Of course, you can add a numbers to the vertical
    time axis on a cladogram
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