Download Notes Evolution

Evolution
A Scientific Theory
Scientific Theory:
Subject to verification
Explains observed phenomena
based
observable scientific facts.
Continually being tested as new
evidence is found
Evolution is change
through time:
The traditional
view is that
evolutionary
changes were
SLOW and
gradual.
Sharing a
common
ancestor!
EVOLUTION
A theory: is supported by evidence and
generally accepted as true but is not yet
considered a fact
2 main Theories of Evolution
Lamarck’s & Darwin’s
Lamarck's Explanation
Hypothesized that acquired traits were
passed on from one generation to the
next

Acquired traits are traits that are NOT
determined by genes
The acquired trait occurs during the
organisms lifetime from behavior or
experience
Lamarck Cont…
Examples of Lamarck's theory:


Giraffes necks increasing in length
reaching for food  produce offspring with
the longer necks
An athlete who increases muscle mass
producing offspring who have increased
muscle mass
The hypothesis was not accepted and
dismissed
Charles Darwin:
Studied the Galapagos Island

Organisms were isolated
Determined that a small # of plants and
animals started out on the island
Through reproduction and time the
offspring became different from their
mainland relatives
organisms “adapted” to their new
environment
Darwin clip
Darwin's’ studies:
Finches
Charles Darwin: Natural
Selection
Process where organisms that are
able to adapt to their surroundings are
more likely to survive and reproduce
The favored traits get passed on from
one generation to another
Unfavorable traits gradually disappear
because the organisms die out
N.S. leading force in Evolution
Factors that effect natural selection:
1. Overproduction- producing more
offspring than can possible survive
Ex. Sea turtles, fish, amphibians
2. Competition – food and resources
are limited. (only the strongest survive)
3. Variations – slight differences among
offspring some can be beneficial to the
organisms
Adaptations occur only when there are
genetic varieties in the offspring.
Theory of Natural Selection Cont…
Natural Selection- some variations are more
helpful than others therefore a natural
selection against those that cannot adapt
Inheritance of Variations –beneficial,
provides an advantage for the organism
Survival of the Fittest – variations that
allows an organisms to live and reproduce

Ex. Brown fur color in woodlands vs. white fur
Adaptations:
occur only when there are
genetic varieties in the
offspring.
Mutations:
Are large variations in the offspring that
randomly occur in the genes
Some are harmful….
albino mouse…?
Some are beneficial…
brighter flower petals…?
In general, organisms change over time
through mutations and sexual reproduction
Proof (Evidence) of Evolution:
1. Body structure – Homogulous Structures
Similarities in body and skeletal structure
Vestigial structures:
Tailbone, appendix, molars
Ex. Homogulous Structures
Homologous Structures vs.
Analogous Structures
Homologous structure = similar body parts
found in different species
Analogous Structures = Structures used for
similar purpose BUT not similar in
structural makeup:
Ex. Butterfly wing and Bird wing
both used for flight but one has bone
other does not
Proof (Evidence) of evolution:
2. Early Development
Comparing the embryonic
development
many vertebrates look very
similar during early
development
1
2
3
4
5
Which one in the: Turtle, chicken, eel,
human, cat?
Evidence of evolution:
3. Similarities in DNA
the more amino acids 2 organisms
share, the more closely related they are
believed to be
ex. The protein (coded for by amino
acids) in blood:


67 different amino acids b/w human and
frog.
only 1 amino acid difference between
humans and gorilla’s
Evidence of evolution:
4. Fossils
Formation of fossils remains of organisms
become buried
sediments: soils, rocks build up and cover the
remains
these layers harden and become SEDIMENTARY
ROCK
types include:
1. casts
2. imprints
3. Petrifaction
4. can be found in: ice, tar pits, rock, amber
STOP!!! CK POINT!!
Topic: Evolution-Darwin
1. DNA in humans, gorillas and chimpanzees is
more than 98% the same. Which answer
best explains this

They evolved from the same ancestor

They evolved from each other

Their evolution is complete

They evolved at the same time
STOP!!! CK POINT!!
Topic: Evolution-Darwin
2. Many scientists believe the earliest cells on Earth
were relatively simple, lacking nuclear membranes and
other cellular structures. Over time, more complex cells
developed from these simple cells. These statements
describe the concept of
1 inheritance of acquired characteristics
2 evolution
3 dominance
4 use and disuse
STOP!!! CK POINT!!
Topic: Evolution-Darwin
3. What causes insect populations to evolve and
become resistant to chemical insecticides?
a. Biological control
2. low survival value
3. natural selection
4. vegetative propagation
STOP!!! CK POINT!!
Topic: Evolution-Darwin
4. Biochemical analysis uses similarities in which
of the following as evolutionary evidence?
1. Amino acid sequence
2. Bone structure
3. Cellular architecture
4. movement
STOP!!! CK POINT!!
Topic: Evolution-Darwin
5. In the early stages of development, the embryos
of dogs, pigs, and humans resemble one another.
This observation suggests that these animals may
have
1 a similar number of chromosomes
2 similar habitat requirements
3 the same blood components
4 a common ancestry
FossilsExamples
youngest
oldest
Layers (strata) of fossils
mold
Types of Fossils
Petrified
Turned to stone.
The soft parts of
the organism are
replaced with
minerals.
Types of Fossils
Imprint on a rock (mold)
Imprint on a rock (mold)
 Turned to stone.
The imprints
are replaced
with minerals.
Types of Fossils
AMBER
Organisms
trapped liquid
tree sap.
Soft body parts
stay preserved.

Types of Fossils
Bones
preserved in
tar pits
Organisms
trapped in tar
pits. Soft body
parts stay
preserved.
images
10,000
year old
fossil
ADD TO YOUR NOTES!!
Proof (Evidence) of Evolution:
5.
Structural Adaptations:
Structural differences that are
inherited
 Ex.

Mimicry: one specie looks like
another
Cont.
Ex
Camouflage: cannot be easily seen,
blend in with their environment
STOP!!! CK POINT!!
Topic: theory of evolution
From pg. 37:
#6.
#9
From pg.38:
#11
#15
#18
Patterns of Evolution:
Patterns in evolution were recognized
Include:
 Use of pesticides and antibiotics
 Co-evolution
 Convergent evolution
 Divergent evolution
Adaptive radiation
Use of Pesticides &antibiotics
Modern Times:
Use of Pesticides
ex. NY black flies sprayed with
pesticide DDT
most of the flies disappeared, some
were resistant
those resistant reproduced,
increasing in #
Thus producing pesticide resistant
flies
Use of Antibiotics:
new antibiotics continuously
developed because bacteria
become resistant to old meds
Viruses/bacteria changing
strains, vaccines are not
effective
Ebola
Virus
Co-Evolution:
A change in a species
in response to one
another
The pressure on one
influences which
specie
will thrive for the other
Ex. A flower and
the animal that
pollinates it
Convergent evolution
Organisms that are not related
but very similar in appearance
Similar Environmental demands
work on 2 different organism
Results in similar appearances
 Ex. Shark (fish) and
dolphins (mammals)

Convergent Evolution Ex
DOLPHINS
Divergent Evolution
Species become more different over
time
A response to different habitats
Ex. Adaptive Radiation



Many new species evolve from a single
ancestor
Finches on the Galapagos Island
Various primates
Divergent Evolution Cont.
DE can occur on its own or be
accelerated by outside forces
(man)

Ex. Peppered Moths
Peppered Moth:
2 basic colors: light and dark
before Industrial Revolution light
moths able to blend and avoid
predators, the dark moths stood out
to predators therefore decreased in
population
after the I.R., the trees covered in
soot, making the dark moth less
visible than the white moth
white moth population decreased
Before IR
After the IR
Behavioral Evolution:
certain behaviors that result in greater
reproductive success
ex. Moths that remain motionless
when resting verses those that flap
wings.
The motion is visible to predators and
therefore eaten
Resting moths live longer and
reproduce more often
Selective Breeding
Mating organisms for
particular traits
Ex. Horses, gray hounds,
(natural selection, nature acts
as the selecting agent…not
humans)
Geographic Isolation:
Population that is physically
separated into smaller
populations by barriers
Geo barriers could include: river,
shopping malls, deserts,
mountains, expressways…
Can lead to speciation- new
species evolving from a common
ancestor
Types of Natural Selection
1. Stabilizing Selection
2. Directional selection
3. Disruptive selection
Stabilizing Selection
Favors average
individuals in the
population
Reduces variation
Directional Selection:
Favors one of the extreme
variations of a trait
Can lead to rapid evolution
of a population
Disruptive Selection:
Favors both extreme variations of a trait
Results in no intermediate forms of the
trait
Leads to evolution of 2 new species
(speciation- members of a similar
population change and can no longer
reproduce fertile offspring)
2 theories involving
Rate of Change:
Gradualism
vs.
*Slow, gradual,
Continuous change
Punctuate Equilibrium
*long periods of stability
with brief periods of
major change
***Models used to show derived traits based on
evolutionary history are called Cladograms
Cladogram
Gradualism - Darwin
Cladogram
Punctuated Equilibrium- LaMark
Review: Evolution
jeopardy