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Transcript
EVOLUTION!
Many misconceptions
All that it means=
LIVING THINGS CHANGE OVER TIME
TIME
 Origin of the universe- Big Bang??
 Evidence? Yes- red shift, cosmic background
noise
 Age of universe= 10-20 billion years
 Geologic time
 How old is Earth?
 Approximately 4.6 billion years old
 Many changes can occur
Has Earth Changed?
 Yes
 Observe the continents- what do you notice?
 At one point all continents were together=
PANGEA- http://geology.com/pangea.htm
 They began to split= Laurasia(north) and
Gondwanaland (south)
 How did they move?
Origin of Life?
Spontaneous Generation
Observation- meat left out to spoil,
maggots develop
Belief- maggots spontaneously arise
Francesco Redi said ABSOLUTELY
NOT!
Redi’s Experiment- 1668
2 jars 1 with meat left open to air
 1 with meat that is sealed
Results?
Maggots only in open jars
Redi’s Exp. Step 2
People argued that air was necessary
for spontaneous generation
Redi seals jars with cloth to let air in but
not flies
Spallanzani’s Experiment-1775
People were still skeptical
Boiled broth and placed in sealed flask
No organisms develop- people still
skeptical- no air in flask
Louis Pasteur-1859
 Uses swan neck flask
 Boils meat broth in flask and bends neck of
flask into S shape
 Air can enter but airborne microorganisms
cannot- they settled in the neck
 No microorganisms grew- FINALLY- no
spontaneous generation- life comes from life
 BIOGENESIS
How did life begin?
4.6 bya- earth was very different
 Atmosphere of methane, carbon dioxide,
nitrogen, water vapor, but no free oxygen
 Intense solar radiation, lightning, volcanic
activity
First living organisms
Possibly self replicating RNA molecules
Eventually acquired a protective lipid
coating
Becomes something resembling today’s
bacteria
But how?
Oparin’s Hypothesis
 Ancient earth’s conditions led to spontaneous
formation of organic molecules (what are the
main 4?)
• These accumulated in oceans and combined
into cells
• http://vilenski.org/science/notebook/unit1
/historyoflife/oparin.html
Miller-Urey Experiment
 Simulated
conditions on
ancient earth
 Successfully
synthesized amino
acids
 Confirms Oparin’s
hypothesis
 Some holes in this
idea
Penn State Research- very new
 Organic compounds have been located in
material in space (comets, meteorites, clouds
of gas)
 Membrane forming molecules have been
found in some meteorites
 Comets/meteorites bombard earth and give
rise to life????? Problem?
Oparin’s Idea Revisited- By PSU
More evidence shows that first
organisms were thermophilic (could
thrive in earth’s early state)
Life arises at bottom of ocean as
thermophilic microorganisms
So What happened next?
 Several Different Theories
 Endosymbiotic Theory
 Jean Baptiste De Lamarck- Acquired Traits
 Charles Darwin- Natural Selection
 Devries
 Gould
ENDOSYMBIOTIC THEORY
One Idea
 Organisms change over time by
adapting
Adaptations
Structures/traits that are beneficial and
serve a purpose to an organism or
species
Examples?
Let’s go outside
ACQUIRED TRAITS- Lamarck- Late
16th century
Adaptations are acquired throughout and
organisms life and passed on.
Adaptations are results of organisms
using or not using body parts.
Acquired Traits
INCORRECT!
CHARLES DARWIN
Takes a ride on the HMS Beagle.
Stops @ Galapagos Islands- observes
Finches
http://worldatlas.com/webimage/countrys
/samerica/galap.htm
Comes up with theory of Natural
Selection
Darwin’s Ideas
2 Key Points
Species of Organisms descended from
common ancestors (adaptive radiation)
 “Descent with Modification”
Natural Selection- best suited individuals
survive and leave more offspring
DARWIN-1859
 THEORY OF NATURAL SELECTION
 established that change occurs in organisms without
respect to need
 environment determines whether or not a variation
improves the chance of survival
 change occurs gradually
never said that man evolved from apes!
 infers that man and ape had a common ancestor
THEORY OF NATURAL SELECTION
Key Ideas
OVERPRODUCTION
plants and animals over produce
limiting factors exist to balance populations
and prevent extinction due to competition
STRUGGLE FOR EXISTENCE
competition exists for food and other
resources
food chains become established
VARIATION
individuals in a population vary- polygenic
traits (humans, etc)
they vary whether they need to or not
some variations have an advantage in the
environment
SURVIVAL OF THE FITTEST
those with the variations best adapted to
the environment will survive
survivors reproduce and pass on traits to
offspring
ENVIRONMENTAL INFLUENCE ON
EVOLUTION
THE ENVIRONMENT DETERMINES IF
A VARIATION WILL HAVE SURVIVAL
VALUE
THE ENVIRONMENT DETERMINES
WHAT DIRECTION EVOLUTION WILL
TAKE
CHANGES IN ENVIRONMENT
MIGRATION
movement to a new environment- when 2
gene pools mix, new traits will emerge
new mutations give offspring greater
survival value
WITHIN THE OLD ENVIRONMENT
geologic impacts like volcanoes
resistance to antibiotics, pesticides
INDUSTRIAL MELANISM is a change in
coloration caused by industrial pollution
ISOLATION
a split between interbreeding groups
caused by geographic/physical barriers
produces changes in behavior, color, which
prevent them from breeding
DEVRIES-1901
 MUTATION THEORY OF EVOLUTION
 sudden changes in genes results in new
types of plants and animals
 accounts for the variations suggested by
Darwin
 mutations can be good, bad, or have no
current value
 lethal genes which leaves organism with no
chance of survival (almost always recessive)
GOULD-1972?
 PUNCTUATED EQUILIBRIUM
 agrees with Mutation Theory
 disputes Darwin’s gradualism-but not natural
selection
 supports idea that evolution occurs in quick spurtsseen in fossil record all the time
 mutations accumulate over time and then a new
species develops when there are too many
differences between them
 there are no missing links
SPECIATION
SPECIES is a group of organisms that
are similar in structure and can mate and
produce fertile offspring--all have the
same number of chromosomes
CAUSES
natural selection
--mutations
change in environment
migration
--isolation
 EVOLUTION OF A NEW SPECIES
 each generation inherits variations that are
adaptive
 each generation forms new variations
 Gene Flow, Genetic Drift (chance)
 over a period of time, accumulations of variations
will result in a new species
 if variations are unfavorable, the species will
become extinct
PATTERNS OF EVOLUTION
ADAPTIVE RADIATION
different species develop from a common
ancestor
CONVERGENT EVOLUTION
organisms with different ancestors become
more alike in shape, form, behavior...
generally because they share the same
environment
EVIDENCE FOR EVOLUTION
fossil record
Homologous structures
vestigial structures
embryological evidence
biochemistry
Fossil Records
fossils at various depths show different
forms of life
lineages of fossils of a particular group
are found and quite complete
Radiometric (radiation) dating of rock
layers establishes a chemical connection
between fossils
Homologies

similarities in structure and arrangement of parts
 indicates genetic relationships of common ancestor
 suggests environmental influences on adaptations
selected
Vestigial Structures
 structures of modern
organisms with little to no
function
 structures are often
degenerate in appearance
 fossil evidence suggest
structures once had a
function
Embryological Evidence
similarities in development of the
embryos of various organisms into
differentiation of tissues
currently, this view point is being
scientifically challenged
Biochemistry
similarity of DNA in terms of identical
genes
similarity of hormones, digestive
enzymes, ATP
EXTINCTION OF THE
DINOSAURS
METEOR
DISEASE
CHANGE IN ENVIRONMENT
NEW SPECIES ADDED COMPETITION
RISE OF MAMMALS
 Mammals existed for 150 million years with
dinos
 LOSS OF DINOSAURS OPEN NEW NICHES
 BETTER ADAPTATIONS
 CARE FOR YOUNG
 PLACENTA
 WARM BLOOD
EVOLUTION OF MAN
man is an animal
man is subject to the rules of natural
selection
man changes over time
A FINAL WORD
most reasonable people (including the
pope) understand that organisms evolve
the argument is not over “IF” it occurs,
but “HOW” it occurs
belief that things change does not
challenge religious belief