Transcript Evidence_for_change

Part I. History of Evolution
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The continuing process of genetic
change in a population of organisms
over long periods of time is called:
EVOLUTION
Over a large number of years,
evolution produces tremendous
diversity in forms of life.
Scientific Theory
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A well supported testable explanation of
phenomena that have occurred in the
natural world.
(A theory is both verifiable and falsifiable)
(A theory is not the result of one person’s
ideas)
Science at work
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Observation: Every swan I've ever seen is white.
Hypothesis: All swans must be white.
Test: A random sampling of swans from each continent where
swans are indigenous produces only white swans.
Publication: "My global research has indicated that swans are
always white, wherever they are observed."
Verification: Every swan any other scientist has ever observed
in any country has always been white.
Theory: All swans are white.
History of Evolution
Original Beliefs
• species could not change
•Geology has not changed
•fixed number of species
•species had a given set of traits that remained with
it forever.
Jean Babptiste de Lamarck, Charles Darwin, Charles
Lyell, Alfred Wallace led the way in the search for
the mechanisms that cause change.
1. Jean Baptist De Lamarck
1809 –proposed a hypothesis
to explain the variation in organisms.
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Acquired Characteristics- traits that
developed during a lifetime could be passed
on to the offspring.
 I.e. giraffes stretched their necks over a
lifetime to reach food. They then passed on
the longer neck trait to their offspring.
Rejecting Lamarck’s Hypothesis
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Large amounts of
data showed that
acquired traits are
not hereditary.
2. Charles Lyell
(1797 – 1875)
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Geologist
 Theorized that geologic
features are constantly
changing.
Published in 1830
3.Charles Darwin
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1831 took a voyage on the H.M.S
Beagle to the Galapagos Islands
and collected a lot of data.
 Natural Selection- a mechanism
for change in a population that
occurs when individuals with the
most favorable variations for a
particular environment survive and
pass these traits on to offspring.
Natural Selection
1. Variations exist within populations.
2. Some variations are more advantageous
for survival and reproduction than others.
3. Organisms produce more offspring than
can survive.
4. Over time, offspring of survivors will
make up a larger proportion of the
population.
Peppered Moths
Variation in moths some
black some light colored.
In 1850 most were light.
Industrial revolution
covered trees with smoke
and soot. Now the dark
moths were better suited
for the environment.
4. Alfred Wallace (1823-1913)
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Father of Biogeography
 Studied plants and animals
in Amazon vs. Australia.
 Independently of Darwin
and proposed the same
theory.
Part II. Mechanisms of Evolution
Without environmental pressures genetic
equilibrium is established.
How can the equilibrium be changed?
A. Changes in genetic Equilibrium
1. Mutations are changes in genetic
material of an organism. Provides new
genetic material in a species.
Mutations are random
Changes in genetic equilibrium
2. Genetic Drift – the change in allele
frequencies of a population as a result
of chance processes.
The survival and
reproductions of
organisms is
subject to
unpredictable
accidents
See an example
Changes in genetic equilibrium
continued
3. Gene Flow is the movement of genes
in and out of the gene pool.
Gene flow increases genetic variation within a
population
Patterns of Evolution
A.
B.
Patterns of Evolution
c. Adaptive Radiation – species adapting
to different environments and become
a new species.
Recap
video
Evidence for change
Fossils- provide scientists with strong
records of the earth’s past.
A fossil is the remains of an organism
preserved in the earth’s crust
Where are fossils found?
Found in layers of
sedimentary rocks.
 Organisms were
buried in layers of
mud and or sand.
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4 types of fossils
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Imprint
 Mold
 Cast
 Petrified
Imprint Fossils
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The soft parts of
buried organisms
decay and leave an
imprint in the stone.
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I.e. animal tracks
and plants
Mold fossils
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The hard parts of an
organism decay and
leave indentation in
the rock.
Cast Fossil
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A mold fossil fills
with mineral or rocks
Cast Dinosaur eggs
Petrified Fossils
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Highly porous
materials like bones
or wood can
become petrified if
they are buried
quickly and
thoroughly.
More Petrified Fossils
Relative Dating
Relative dating tells scientists if a rock
layer is "older" or "younger" than
another.
 fossils found in the deepest layer of
rocks in an area would represent the
oldest forms of life in that particular rock
formation.
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Evolution of the horse
Living organisms
resemble most
recent fossils in
the line of descent;
underlying
similarities allow
us to trace a line of
descent over time.
Absolute Dating
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The use of
radioactive isotopes
to date fossils and
rocks.
 A radioactive
isotope is an atom
with an unstable
nucleus and decays
at certain rate.
Half-Lives of Selected
Radioactive Isotopes
Isotope Half-Life
 14-C
5730 y
 24-Na
15.0 h
 32-P
14.3 d
 36-Cl
3.1 x 10+5 y
 40-K
1.28 x 10+9 y
 45-Ca
165 d
 226-Ra
1.62 x 10+3
y
 235-U
7.1 x 10+8 y
 238-U
4.51 x 10+9 y
 239-Pu
2.44 x 10+4
Homologous Structures
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Structures that are similar and are
derived from the same body parts.
Vestigial Structure
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Body parts that are reduced in size and serve no
apparent function.
I.e – Human tail bone – no function
Examples of Vestigial Structures
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Human appendix useless yet in other
mammals, including primates, it is necessary
to aid in digestion of high cellulose diet
Human external ear muscles still present but
useless
Humans have tailbones and some babies
occasionally have tails
Human wisdom teeth vestigial compared to
other primates
Some snakes have skeletal limbs
Cave dwelling crayfish have eyestalks yet no
eyes
Analogous Structures
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Body part that have
similar functions but
originate from
different structures.
Examples of Analogous
structures
structures "fitted" for a particular
purpose tend to be similar, regardless of
origin
 flippers in dolphins, penguins and fish.
 wings have developed independently in
insects, reptiles, birds, and bats
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Embryonic Development
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Gill slits and tail in
human embryo
show similarities of
embryos of
dissimilar
organisms.
Biochemical Analysis or
DNA/RNA Comparisons
The more closely related organisms are, the more similar
is their biochemical makeup
• Cytochrome C, a protein
•Humans differ by 1 nucleotide compared to monkeys
•Humans differ by 19 nucleotides compared to turtles
•Digestive Enzymes in Felines – Cougar vs. house cat
Adaptations
A variation in an organism
that makes it better able to
cope with it’s environment.
Structural Adaptations
 An
organism
changes the
structure of
body parts
Wow! Is that a leaf?
MIMICRY
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When a population’s
natural selection
results in the
appearance of the
organisms being
similar to another
species.
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The Moth’s Wings
mimic the eyes of an
owl.
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Isn’t that a HOOT!
Viceroy- very
tasty (bottom)
mimics the
poisonous
Monarch
(top) Butterfly
The “meat eating” venus fly trap
mimics a normal plant.
Waiting for the prey
Insects are attracted because of the sweet
tasting nectar.
The soil that this plant lives in is
nutrient poor so the population has
adapted to catch prey (and nutrients).
Warning Coloration
Bright colors indicates DANGER to predators
Bright yellow
markings on the
Gila Monster
indicates it is
poisonous.
WARNING DON’T EAT
THE MUSHROOMS
Bright colors indicate that
it is poisonous.
Camouflage allows organism to blend in
with its surroundings.
Cryptic coloration - a color or pattern of
coloration which blends in well with the visual
appearance of its habitat
The Grey Tree
Frog blends in
with the bark on
a tree.
No lichen on trees
Lichen on Trees
The peppered moths demonstrate how they adapt to the changing
environment. Pollution killed the lichens on the trees which allowed the
light colored moths camouflage. The Dark colored moths adapted to
blend in with the bark. Can you see the four moths?
The Aphid Lion disguises himself by attaching the remains
of his prey to his back, making himself look like a crawling
junkyard. Predators may overlook this unappetizing sight.
The Snow
shoe hare
has been
adapted
to change
color in
the
winter.
Physiological Adaptations
A change in an organisms metabolic process.
Plants must either adapt to changes in the environment or die. They
can’t move to a favorable climate. For example, desert plants can live
in a warm dry environment.
Autotrophs adapt based on the availability of sunlight,
water, and Carbon dioxide to manufacture the food they
need.
Deer have been adapted to the
cold winter by natural selection
to have a warm fur coat.
Behavioral Adaptations
behavioral patterns allow for survival
Courtship Rituals
A Tom strutting his
stuff!!
The strongest ram will
mate with the ewes and
pass on his genes.
Using Tools
WoodPecker Finch uses
a cactus spine to get
grubs out of a tree.
Using Tools
This shrike uses a thorn to kill the grasshopper.
Chimpanzees love to eat
termites. A stick
becomes a handy tool for
collecting the juicy
insects.
More behavioral adaptations.
The archer fish spits
water, knocking an
unsuspecting bug into
the water.
Can you tell what special adaptations these creatures have?
Structural, physiological, behavioral
What type of adaption?
Timema (walking-stick insects) live and feed on a range of
different plant species. Sometimes adaptation to living on
these different plants involves not only camouflage, but
also the ability to detoxify harmful plant chemicals.
The evolution of a species is the direct result of innumerable
genetic errors allowing the organisms to become better
adapted to its environment.
Man causes a tremendous amount of change to his
environment. What happens if change occurs too fast?
Some populations may adapt
and live in an environment
changed by humans.
Others may not be as fortunate!
70 million years ago the giant dinosaurs mysteriously
vanished from the earth.
The next great
dying out may not
be a mystery!