Download EvolutionNotes - WordPress.com

UNIT IV:
EVOLUTION, CHANGE AND DIVERSITY
Why is the topic of evolution so controversial?
https://answersingenesis.org/theory-of-evolution/in-schools/
https://www.youtube.com/watch?v=UdXHktAAOcc
Modern Day Evolution
Industrial Melanism- The Peppered Moth
• An example of evolution
• It highlights the importance of variation within a species
and how this adaptation can help them survive.
Peppered Moth Stimulation
http://www.techapps.net/interactives/pepperMoths.swf
Page 2 in Booklet
Before
During
After
- Light moths
were more
common
- Light and dark - Dark moths
moths equal in
became more
number
common
- Trees were
light, so dark
moths got
eaten
- Trees were
light & dark
- Most trees
were dark from
pollution, so
light moths got
eaten
Adaptation- an inheritable characteristic that
helps an organism survive and reproduce in an
environment.
Variation- the differences in characteristics of a
species.
Natural Selection
Artificial Selection
• A process where
individuals with
favorable traits survive
to pass on their traits to
their offspring
• A process where a
breeder decides what
traits will be passed
on
• Ex: Peppered Moth
• Ex: Dog breeding
Contributions of Scientists
Page 3 in Booklet
Georges Cuvier
• Developed the science of
paleontology (fossils)
• He believed catastrophism
caused new species
Thomas Malthus
• He proposed the theory of
population growth
• There is not enough food to feed the
growing world population
Charles Lyell
• Evolution is slow and gradual
• He believed in
Uniformitarianism
Jean Baptiste Lamarck
1. Law of use or disuse
2. The Law of Inheritance of
Acquired Characteristics
1.The Law of Use or Disuse
•
Use it or lose it
If an organism uses a trait it remains active and strong, but if not
used then it becomes weak and disappears.
2. The Law of Inheritance of Acquired Characteristics
•
Favorable traits can be passed on to the next
generation.
• Since giraffes stretched their necks during their lifetime
then this trait was passed onto their offspring.
Modern Day example that disproves the theory
of "inheritance of acquired characteristics":
Chinese women bound the feet of their infant
children for several thousand years, yet the feet of
Chinese women today are normal in size.
Alfred Russell Wallace
• Forced Darwin to publish
his book, he was working on
a similar theory
Charles Darwin
Developed the theory of Natural
Selection (survival of the fittest)
Don’t write:
His came up with his theory after
consulting several different sources:
A. Maltus’ Essay
B. Selective (Artificial) Breeding
C. Lyell’s Book
D. Darwin’s Personal Observations
https://www.youtube.com/
watch?v=6GNUlZhE_jE
Page 4 booklet
Explain how the finches evolved on the Galapagos
Island.
1st – variation within the species (ex: beak shape)
2nd – those with the “best” adaptations were more
fit (ex: large beak to crush seeds)
3rd – they survived in the environment
4th - passed on their traits to offspring
Page 4 booklet
Why is the medical community concerned about
the overuse of antibiotics?
• People often don’t take all their antibiotics
• As a result, all the bacteria are not killed
• The strongest bacteria is left to reproduce and
pass on their traits to the offspring, making
extra strong bacteria that are resistant to
antibiotics
Finish pages 4 and 5 in Booklet for homework
These are practice questions
Support for the modern theory of evolution
•
Scientific evidence we use to support the theory
of evolution
1. Biogeography
•
The study of the geographic distribution of a
species.
Video: Island of Lemurs
https://www.youtube.com/watch?v=Q_7cVyM8Efg&safe=active
2. Comparative Anatomy
a. Homologous
structures –Anatomy is
similar in shape, structure and origin.
b. Analogous structures
• similar structures but are anatomically
different.
This is evidence to suggest theses
organisms did not evolve from a common
ancestor.
c. Vestigial organs - structures that have lost
their function, but were functional in an
ancestor of the organism.
Video: Evolution of Whales
http://ocean.si.edu/oceanvideos/evolution-whalesanimation
3. Comparative Embryology
•
Compare the structures of the embryos
Similar structure is evidence for close evolutionary relationship
4. Comparative Biochemistry/
Molecular Biology
• Scientists compare the chemical composition
(DNA) of different organisms.
Examples:
Hemoglobin of monkey’s is similar to the hemoglobin of man.
The insulin from a pig or cow can be used to treat diabetes in humans.
5. DNA sequencing
• Compare the sequence (order) of DNA
Example:
• Humans and chimpanzees have 2.5% difference in their DNA
sequence
• Humans and lemurs have 42% difference
• Therefore humans are more like chimpanzees than lemurs
6. Fossil Record
Relative Dating - an estimate of the age of
a fossil by its location in sedimentary layers
(oldest on bottom)
a.
•
Scientists have discovered that it takes approximately
1000 years of sediment to produce 30 cm of
sedimentary rock.
Example: 150cm deep means a
relative age of 5000 years.
b. Absolute Dating - an exact age of a fossil
done by radioactive dating
Living organisms accumulate certain radioactive isotopes when
they are living. Once these organisms die, the radioactive
isotopes start to breakdown. The rate of this breakdown is called
half life.
The greater the amount of decay
product the older the fossil.
How to do a half life problem
# of Half Lives
Fraction
Percent
Age
1
½
50%
5730
2
½x½
25%
5730 + 5730 = 11460
3
½+½+½
12.5 %
5730 + 5730 + 5730 = 17190
4
½+½+½+½
6.25%
5730 + 5730 + 5730 + 5730 = 22920
5
½+½+½+½ +½
3.125%
5730 + 5730 + 5730 + 5730 + 5730 =
28650
Half-Life Problems
(page 8 in notes)
• Carbon 14 has a half life of 5730 years. How long will
it take for carbon 14 to decay to 1/8 of its original
amount?
Examples include some of the isotope pairs
found in the following table:
Isotope Pair
Half-Life in Years
Useful Range in Years
Carbon 14/Carbon 12
5730
60 x 103
Uranium 235/Lead 207
700 x 106
Over 500 x 103
Potassium 40/Argon 40
1.25 x 109
Over 500 x 103
Uranium 238/Lead 206
4.5 x 109
Over 100 x 106
Half Life Problems
Page 7 in Booklet
1. Carbon 14 has a half life of 5730 years. How
long will it take for C14 to decay to 1/16 of its
original amount?
2. Uranium has a half life of 700 x 106 years.
How long will it take for uranium to decay to ¼
of its original amount?
3. The half-life of carbon-14 is 5730 years. How
old is a fossil that contains 6.25 % of the
original carbon-14?
4. If the half-life of carbon is 5730 years, what
percent of carbon would be contained in a
rock sample that is 22 920 years old?
Finish pages 8 and 9 in Booklet for homework
These are practice questions
Hardy-Weinburg Equilibrium
Page 10 in Booklet
• Used to determine whether or not evolution is
occurring in a population.
• The law states that under certain conditions, allele
frequencies will remain constant (genetic
equilibrium) in a gene pool and there will be no
evolution.
http://www.youtube.com/watch?v=JsuJlew
aPX0&safe=active
Five Conditions
1.
The population must be large. (No genetic
drift)
2.
Individuals must not migrate into or out of the
population
3.
Mutations must not occur
4.
Reproduction must be completely at random.
5.
No genotype is more likely to survive and have
offspring than any other genotype.
Allele frequency
p+q=1
p is the dominant allele frequency
q is the recessive allele frequency
Genotype frequency
p2 + 2pq + q2 = 1
p2 homozygous dominant frequency (TT)
2pq heterozygous dominant frequency (Tt)
q2 homozygous dominant frequency (tt)
Practice Public Exam Question
1. A teacher observed that the frequency of
students able to roll their tongue has decreased
over thirty years. Is this population in HardyWeinberg Equilibrium? Give three reasons to
support your answer.
Answer:
How can you tell evolution is occurring?
If the allele frequency in a population changes,
then the Hardy-Weinberg Law fails and it is
therefore a sign that evolution is occurring.
Page 11 in Booklet
2 (a) in 30 pea plants, they have 60 alleles
present for height (each plant has 2 alleles). A
survey tells you that the frequency of the T
allele 0.6 (60%) and the frequency of the t allele
is 0.4 (40%). You can use the Hardy-Weinberg
formula to calculate the genotypic frequencies
of the population.
(b) Let’s assume that for the next few years,
some pollen from another nearby garden of
plants fertilizes some of the pea plants in your
garden (in migration and random mating have
occurred). Years later, you survey your plants for
height and find that the T allele frequency is
now 0.73 (73%). What does this prove? Explain.
3. A biologist has found that 10 percent of a
population of bats are hairless, which is a
recessive trait. Assuming that the population is
Hardy-Weinberg Equilibrium, determine the
genetic structure (genotype and allele
frequencies) of a population?
Mechanisms for Variation
•
There are FIVE mechanisms that can affect
the biodiversity of a population.
1.
2.
3.
4.
5.
Small population (Genetic Drift)
Non-random mating
Mutations
Gene Flow
Natural Selection
5 finger evolution
• http://www.youtube.com/watch?v=5NdMnlt2
keE&safe=active
2. Genetic Drift
•
In large populations, genes expressed will be
similar to the parent generation
(mutations are not noticeable in large populations)
•
BUT, in very small populations, the
frequencies of particular alleles can be
affected drastically by chance alone
This is called genetic drift.
There are 2 types of genetic drift:
A. The Bottleneck Effect
• When a population is greatly reduced
because of things like natural disasters
(earthquake, fire, flood), overhunting, and
habitat destruction
• The gene pool is therefore much smaller
leaving fewer variations in the population.
B. The Founder Effect
• When a small number of individuals colonize a
new area, they will probably not possess all the
genes represented in the parent population.
• Since this new population has moved to a new
environment, there would have different
environmental selective pressures affecting
them than the parent population would have.
Ex: Type O blood is recessive, yet the most common blood type in NL
2. Non-Random Mating
•
Any situation where individuals do not
choose mates randomly from the whole
population.
•
Ex: Inbreeding, or choosing mates because
of proximity, or choosing mates for similarity
of phenotype (ex. Dogs)
•
Leads to a decrease in genetic diversity.
3. Mutations
•
If a mutation occurs in a germ cell (sex cell) it alters
the DNA of the gamete and can be passed on to
future generations.
•
A mutation is unlikely to cause evolution in the
population unless it provides a selective advantage
(makes it easier for the organism to live in their environment).
•
Unfavorable mutations may provide a selective
advantage when the environment changes
(ex: Antibiotic resistant bacteria)
4. Gene Flow
•
The movement of new alleles into a gene
pool and the movement of genes out of a
gene pool.
•
Ex: A windstorm or tornado can bring new
seeds or pollen or even birds into a
population.
5. Natural Selection
•
Survival of the fittest
•
These members survive to pass on their
genes to the next generation.
•
Four types of natural selection
(turn to page 13 in Booklet)
A. Stabilizing Selection
•
•
•
Favors the intermediate phenotype
Result: Population stays the same
Ex: Medium colored moths due better than
light or dark moths
B. Directional selection
• Favors phenotypes at one
extreme
• Result: population shifts in
the direction of that
extreme.
• Ex: the environment became
polluted so dark moths did
better
C. Disruptive (diversifying) selection
•
Favors both extremes of
the phenotype
•
Result: two new
populations result
•
Ex: Light moths and dark
moths do well, medium
colored die off
D. Sexual Selection
•
•
One sex of a species uses adaptations to
compete for a mate
Ex: Male peacocks have brightly colored
feathers
Finish pages 14 and 15 in Booklet for homework
These are practice questions
What is Speciation?
The image above shows two orchid fish. Each is
a different species from the other that came
from the same common ancestor. How is this
possible?
• They are adapting to the environment in
which they live and as a result are becoming
different species
Turn to Page 16 in Booklet
• Species – a group of organisms that can
reproduce and make fertile offspring
• Adaptive Radiation – a change in the
environment causes a species to adapt and
change into a new species.
Two types:
1. Allopatric Speciation
2. Sympatric Speciation
• Allopatric Speciation – members of a species
become separated from each other (ex: river)
and become different species
• Sympatric Speciation – a new species forms
among an already existing species
What is a Hybrid?
• The offspring that forms when two separate
biological species breed
• the hybrid offspring are infertile or not viable
Ex: horses and donkeys can mate
and produce offspring called a mule
which is infertile.
Types of Biological Barriers
Page 17 in Booklet
• Pre-zygotic – means two species cannot make a
zygote
• Post-zygotic – means a zygote gets made, but
there is an issue with the hybrid (baby)
Pre-zygotic barriers
1.
Behavioral isolation –behaviors do not match so
they are not interested in mating
2. Temporal isolation – Timing is off
Ex: mate at different times in the year
3. Habitat isolation –live in different habitats
4. Mechanical isolation – anatomically
incompatible (their parts don’t fit!)
E. Gametic isolation – gametes are unable to
fuse to produce offspring.
What type of Pre-Zygotic Barriers are shown in each picture?
Video: The Speciation Song
http://www.youtube.com/watch?v=WDPsZPKSE
Fg&feature=kp&safe=active
Video: Speciation
http://www.youtube.com/watch?v=PKb8Yi5xzh
E&safe=active
Post –Zygotic barriers
1. Hybrid in viability –Mitosis is prevented
from happening normally because of
incompatible genes.
2. Hybrid sterility – two species mate and
produce sterile offspring like the mule.
3. Hybrid breakdown –hybrids may be weak
and die
Finish page 18 in Booklet for homework
This is a practice question
Types of Evolution
Page 19 in Booklet
1. Convergent
2. Divergent
3. Co-evolution
Convergent Evolution
• When unrelated species have
similar adaptations due to
occupying a similar niche
• They evolve to share a habitat
Ex: wings are all used for
flight, bats fly at night
Divergent Evolution
• Species that were once similar become two
new species
Co- Evolution
• When two species evolve gradually together,
each one responding to the changes in the
other.
Pace of Evolution
•
At present, scientists do not agree on the
rate at which evolution occurred.
Two opposing viewpoints are:
A. Gradualism
B. Punctuated Equilibrium
A. Gradualism
• new species arise gradually because of small
variations.
• In other words, evolution occurs slowly and
continuously over long periods of time. Based on
Darwin’s theory
B. Punctuated equilibrium
• A species is unchanged for extended periods of time
and then in a relatively short period of time, rapid
change occurs.
• Was proposed by Steven Gould and Niles Eldridge.
The Origin of Life
1.
2.
3.
4.
5.
6.
Chemical Evolution (Big Bang Theory)
Heterotroph Hypothesis
Symbiogenesis
Panspermia Theory
GAIA Theory
Intelligent Design Theory
Haldane- Oparin Theory
(BIG BANG THEORY)
• Early atmosphere was very hot and consisted of:
•
•
•
•
hydrogen (H2)
water vapor (H2O)
ammonia (NH )
methane (CH4)
3
• Oceans were “hot, thin soup” which was perfect
for chemical reactions to occur
• Energy was available to start the chemical
reaction – BIG BANG (UV light, lightening and/or
volcanic heat)
http://www.youtube.com/watch?v=lhTSfOZUNLo&feature=kp&safe=active
https://www.youtube.com/watch?v=28CBRu_kMbY
Miller and Urey Experiment (1953)
• Proved Oparin and Haldane Theory, that life
could come from non-living things
Details of the experiment:
They took methane, ammonia, water and
hydrogen and placed them in a flask.
They exposed the flask to sparks to
represent the sunlight and lightening on
the earth at that time
They discovered that it was possible to
create organic compounds (amino acids)
that could have been the beginning of life
on earth.
2. Heterotroph Hypothesis
• the proposal that the first living organism was
a HETEROTROPH
3. Symbiogenesis
• an evolutionary theory that explains that
eukaryotic cells developed from prokaryotes.
• Organelles inside the cell worked together (symbiotic
relationship) to make a more complex cell
4. Panspermia Theory
This theory suggests that life came from some
other source outside of the earth
http://channel.nationalgeographic.com/channel/videos/theories
-about-lifes-beginnings/
5. Gaia Hypothesis
• It suggests that the earth, including all of its abiotic
and biotic components may constitute a huge, living,
self-regulating system.
6. Intelligent Design Theory
• GOD created earth and all living things
Overview of Evolution
• http://www.youtube.com/watch?v=d4VS00it40o