Evolution on two scales Microevolution- Changes in gene

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EVOLUTION

• Part 1

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I. Preface to Evolutionary Thought

• A. Assumptions made by scientists
• 1. The universe, its contents and its processes
  are knowable.
• 2. The universe and its contents can be explained
  by natural processes.

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B. Characteristics of a Scientific Investigation

• 1. Materialism- grounded in the Laws of Nature
  ex. Gravity, magnetism, physics, nuclear forces,
  entropy, diffusion. Therefore there is no room
  for supernatural involvement.
• 2. Testability- important parts of a concept can
  be experimented upon ex. DNA changes
  hereditary change, nuclear decay dating the
  age of rocks

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• 3. Falsifiable- the potential for a proposed
  explanation to be wrong. Ex . Repeatable
  experiments can test for accuracy
• 4. Peer Review- other professionals in the field
  review the research and results before they are
  allowed to be published. Inaccurate, sloppy or
  unsupported work is not published

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A widely misunderstood concept and occasionally
controversial

• Two separate areas of study are
• the origin of life
• evolution

• Evolution deals with the changes in types and
  make-up of living creatures since the origin of
  life.
• Where and how that first living creature came
  about is a distinct issue. (origin of Life)

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II. HISTORY (thoughts on origins)

• A. Greeks believed gods interacted with human
• (polytheistic , many gods)
• B. Christians and others believed a God created
  the world and its contents
• (monotheistic)

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Creation

• 1. CREATIONISM- supernatural creation of the
  universe and its contents as we see it today.
  (extinction and modification are possible)
• 2. Special Creation -a belief that all types
  of creatures are unique and unchanging species

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Where does this creationism idea come from?

• Literal interpretation of the Bible.
• Read as a history book with factual moral stories
  and descriptions of events.
• Figurative interpretation- of the Bible
• the Bible contains moral stories to help you
  lead your life. Events are recounted to make a
  point.

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Many cultures explain the history of life on
earth with the involvement of a god.

• WHY would some people question supernatural
  involvement ?
• Atheists (dont believe in a god)
• Skeptics (question a gods involvement)
• Others want a NATURAL explanation not a
  SUPERNATURAL explanation for creation and changes
  over time.

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After the Dark Ages people began to look at the
world more critically and
scientifically

• The discovery of fossils made people question
  special creations. (The unique and unchanging
  species created by God in the Book of Genesis.)

• World travel also provided more information about
  the world to the scientists in Europe.

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BIOGEOGRAPHY

• def. The study of the distribution of organisms
  around the world
• posed problems for early observers because unique
  organisms on islands had similar relatives on
  continents.
• Swamps in different parts of the world had
  different species

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EVOLUTION (its origin and our understanding)

• DEFINITIONS
• 1. Change with time (common)
• 2. The scientific theory proposing that modern
  forms of life have descended from earlier forms
  of life by gradual natural processes of
  modification.

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Evolution on two scales

• Microevolution-
• Changes in gene frequencies in a population
  brought about by mutation, gene flow or natural
  selection.(ex. longer neck giraffe, antibiotic
  resistant bacteria, better eye sight in hawks)

• Macroevolution
• The large scale patterns, trends and rates of
  change among groups of species. (ex. fish lineage
  developing into amphibians, early primate to man)

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IV. Roots of Evolution Geology

• A. Age of the Earth?
• 1. Creationist
• Bishop Usher 1654 Biblical Chronology. Counted
  the ages and generations in the Bible

4004 B.C. Oct. 26 9 a.m.
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• 2. Scientific
• James Hutton Scottish Physician
• (1726-1797)
• Observed Hadrians Wall
• Built in 122 AD.
• Still standing today.
• Observed Edinburough Castle built on inactive
  volcanoe.

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WONDERED?

• "How could a volcano erode in 6,000 years when a
  wall seems not to have changed in 1,500 years?
• Estimated the Earth's age to be in the millions
  of years

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Theory of the Earthpublished by Hutton

• "The surface of the earth appears as it does
  because of gradual geologic changes caused by
  natural processes"
• ex. volcanoes, earthquake, erosion, deposition,
  glaciers, hurricanes

Charles Lyell- furthered these ideas in
Principles of Geology
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Uniformitarianism-

• _________"theory of uniformity"
  geological processes of the past and present
  are the same and are the only processes that
  influence the way we see the world today.

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Catastrophism

• ____________ substantial environmental calamities
  have occurred that have changed the face of the
  earth. extinction was followed by repopulation

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CONTINENTAL DRIFT or PLATE
TECTONICS

• Alfred Wegener Early 20th century
• Initially incorrect explanation but modified
  theory is widely accepted (seafloor stationary
• and continents
• move WRONG!!!!)

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• 10 MAJOR PLATES AND MANY MINOR PLATES UP TO 100
  KM THICK
• Continents ride on the moving crustal plates
  (less dense material )

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Plate Interactions

• As the plates move, some are colliding, some are
  spreading apart, and some are sliding past one
  another.
• Subduction zone When an oceanic plate collides
  with a continental plate it tends to slide down
  under it. This forms mountains and volcanoes.
• Fault zones When one plate slides sideways past
  another. This sometimes causes severe
  earthquakes.

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CONVECTION CURRENTS IN MANTLE CAUSE PLATE
MOVEMENT.
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Radiometric Dating or Radioactive Dating

• Isotope- 1 form that an element can have. Number
  of neutrons is variable between isotopes of the
  same element. (number of electrons and protons
  stays the same)
• Minerals possess radioactive isotopes (give off
  energy and subatomic particles) that decay
  (breakdown) into smaller isotopes.

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• Formed in igneous rock, the minerals grow as the
  liquid rock cools.
• Amounts of the parent (or original) and
  daughter isotopes can be measured in a sample
  collected today.
• The rate of decay can be calculated
  experimentally.
• Half Life is a common unit of measure of the
  rate of break down.

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Radioactive parent nucleus
Decay process
Daughter nucleus
p
p
p
p
Atomic mass decreases by 4 atomic
number decreases by 2
p
p
p
p
p
p
p
p
p
p
Proton
Neutron

p
Alpha particle
Emission of 2 protons and 2 neutrons (alpha
particle)
(a)
Alpha decay

p
p
p
p
p
p
Atomic mass not changed much atomic
number increases by 1 because Neutron becomes
proton
p
p
p
p
p
p
p
p
p
p
p
p
p
Beta particle
(b)
An electron (beta particle) is ejected from the
nucleus
Beta decay

p
p
p
Atomic mass not changed much atomic
number decreases by 1
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
electron combines with a proton to form a neutron
Beta particle
(c)
Electron capture

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Sample Problems

• The half-life of Potassium 40 is 1.3 million
  years. It breaks down into Argon 40
• 1) If an original rock sample contains 200
  micrograms of Potassium 40, how much would remain
  after two half-lives?

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Uranium 238 has a half-life of 4.51 billion years
and decays into Lead 206

• 2) A newly discovered rock sample has 15
  micrograms of Uranium 238 and 105 micrograms of
  the daughter material Lead 206. How old is this
  rock?

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• U238 decays into Pb206 in 4.51 billion years
  (HALF LIFE)
• How much U238 and Pb206 are present in a sample
  after 2 HALF LIVES?
• (original sample is 300 grams)
• U238 75 grams Pb206 225 grams
• How long would 2 half lives be?
• 9.02 billion years

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• How old is an igneous rock sample containing 275g
  U238 and 1925g Pb206?
• 3 x 4.51 13.53 billion years

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V. EVIDENCE OF EVOLUTION FROM FOSSILS

• any evidence of once living creatures
• Where are fossils most likely to be found?

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A. 4 Types of Fossils

• 1. Compression- organic material between layers
  of sediment, Some details can be observed . ex.
  fern frond, fish
• 2. Impression- external shape and form, no orgaic
  matter ex. foot print, limb print
• 3. Mold and cast- external features in one layer,
  then the item itself is replaced by other
  sediments ex. Egg, shark tooth
• 4. Petrifaction- tissues are gradually
  infiltrated by minerals. No organic material
  remains ex. petrified wood

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How impression fossils form (the most common type)
Shells settle on ocean floor
Cast forms when mold is filled in with
mineral water
Rock broken to reveal fossil cast
Rock broken to reveal external mold of shell
Shells buried in sediment
Mold, or cavity, forms when original shell
material is dissolved
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B. Distribution of fossils in layers of rocks?

• many varieties
• and great complexity
  
  
• first fossils were
• aquatic and some
  
  are extinct
• few varieties
• and little complexity

YOUNGEST
Fossils in every layer
OLDEST
STRATIFICATION
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Each geologic time period is characterized by
certain fossils
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Geologic Timescale
Homework Learn Timescale.doc less Epochs
Divisions based on fossils Eon, Era, Period, Epoch
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Correlation of rock layers

• Matching strata of similar ages in different
  regions is called correlation

http//www.uwsp.edu/geo/faculty/ozsvath/images/str
atigraphy.jpg
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Why do organisms disappear from the fossil record?

• 1. unable to adapt to a changing environment
• Ex. lake drying, cooling climate ,glaciers
• 2. out competed by organisms more suitable to the
  new environment
• Ex. reptiles competing with early mammals
• Or fish vs. amminoids

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1. Theory and Evidence

• OLD
• 1. puzzle pieces
• 2. fossil distribution
• 3. sediment layers "Gandwanan Sequence" similar
  geology on the 4 southern continents
• sandstone with
  coal
• black shale
• glacial till

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NEW

• 1. earthquake distribution
• shallow quakes at ridges Mid Atlantic
• shallow and deep quakes at trenches
  subduction
• distribution of the RING OF FIRE pg 303
• 2. Movement of plates can be measured from space
• 3. Dating rocks on opposite sides of ridges

Draw ring of fire on map
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End of geological evidence

• the earth is old and has changed (volcanoes,
  glaciers, earthquakes)
• organisms that lived in the past are now gone
• different organism appear in later rocks than
  in early ones
• therefore new organisms must be developing from
  old ? EVOLUTION

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