Transcript EVOLUTION BY MEANS OF NATURAL SELECTION

 The
change of populations of organisms
over generations.
 The process by which all organisms have
developed from older forms of life
 Old species go extinct (mass extinction)
and new species arise.
DAY 1
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A group of organisms similar in structure
and heredity capable of producing fertile
offspring
*breeding within the species…always
exceptions to every rule…
Examples?
Extra-terrestrial
origin
Creation/Divine force
*Originate from non-living matter
Once Life is here…evolution can occurevolution
is how
life/species change
IS THIS
EVOLUTION?
and develop over time.
*
Ch 21
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Abiotic synthesis of small, organic molecules (amino
acids, nitrogenous bases)
Miller/Urey 1953
◦ “prebiotic soup”, no free O2 + lightning + volcanoes = molecule
◦ Meteorites
+ Clay from volcanic ash
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Making macromolecules… proteins, nucleic acids
Protocells/Protobionts/vesicles
Origin of self replication
inheritance …RNA or DNA?
◦ First genetic material- RNA, ribozymes-catalytic RNA
(ribosomes); protein synthesis
Anaerobic Heterotrophs > Chemautotrophs > Photoautotrophs (cyanobacteria)
Splitting water*O2 > Aerobes, Ozone layer > Endosymbiosis
Exploring Life’s Origins
The road to all Eukaryotes:
• Endosymbiosis leads to• Membrane bound
organelles
• Cytoskeleton
• Chromosomes/nucleus
• Cellular membranes,
transport systems
200,000- Homo Sapiens (11:59:30)
Land
Plants,
Animals
Cyanobacteria
Endosymbiosis
~3.5 bya
Stromatolites
Oldest fossilscyanobacteria
Oldest fossils on Earth
http://www.ucmp.berkeley.edu/precambrian/archean_hadean.php
Shark Bay, Austrailia 2-3,000yo high salt content 100yrs to grow 5cm living fossils
*Eukaryotes or Prokaryotes?
*Anaerobic or Aerobic?
WHAT
*Heterotrophs or Autotrophs?
*Marine or CAME
Land?
*Cyanobacteria- Importance?
*Oldest Fossil?
FIRST??
*Endosymbiotic Theory?
*Why the diversity explosion?
+ Reptiles?
*Amphibians or
*Warm or Cold Blooded?
FYI…
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Eon
Eras
Periods
◦ “firsts”
◦ Major
changes in
diversity
Epochs
Ages
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Widespread and rapid decrease in the amount
of life on earth.
Sharp change in diversity and abundance.
98% of
Documented
Species are now
Extinct.
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How
long will it take?
What causes the changes?
What
evidence do scientists
have to support the Theory of
Evolution?
Fossils
Homologous Structures
Vestigial Structures
Embryonic Development
Biochemical Similarities:
1.
2.
3.
4.
5.
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DNA Sequencing- Universal Code
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Fossils are often found in sedimentary rock,
which is formed from layers of silt and sand
covering dead organisms.
Types of Fossils??
In what ways
is the fossil
record
considered
biased?
Similar structure
and anatomical
position (but not
necessarily the
same function) in
different organisms:
“ICA”
“ICA” = Indicates Common Ancestor
Hand, Paw, Fin, Wing??
•Same lineage, evolving
apart to be more different.
•For example, bats and
horses. Both share the
same lineage as mammals,
but the limb of the bat
became wings while the
horse developed hooves.
•Produces homologous
structures
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Similar Appearance and Functiondoes NOT indicate ICA
Ex- Bird and Insect Wings
Porpoise and Shark Fins
Built on a
different
blueprint
Text p399
Organisms having vestigial structures:
ICA with organisms in which the
homologous structure is functional
……….humans??
The closer the DNA sequences of 2 organisms
are, the more closely related they are.
◦ Humans and chimps have DNA that is 98.4% identical
• DNA and RNA are carriers of genetic information
• The genetic code is universal
• Some Metabolic pathways are conserved (same/similar) across all domains
ARISTOTLE
~335 BC
Species change over time, moving toward a
“perfect state”.
LAMARCK
1744-1829
FIRST to clearly state:
 Types of organisms changed over time
because of natural phenomenon not divine
force.
 New species were modified descendants of
older species.
DAY 2
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“OUT”/ Discredited Ideas….
Theory of Need: a change in the environment
produced a need for change in organisms
1.
2.
Use and Disuse If organs were used- they
remained, if unused, they would disappear.
“Use it or Lose It”….all inheritable changes
Inheritance of Acquired Characteristics Not
determined by heredity; ‘acquired traits’ are
acquired in ones lifetime in response to ones
experience or behavior.
THEORY OF NATURAL SELECTION
Organisms with traits more
favorable to a particular environment
are more likely to pass on those traits
to their offspring. *Environment plays
a key role.
(HW Ch 18)
WHERE LAMARCK FAILED:
INDIVIDUALS DO NOT EVOLVE, POPULATIONS DO
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H.M.S. Beagle
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1831-1836
BACKGROUND
EDUCATION
REV. JOHN HENSLOW
VOYAGE
 1856 Alfred Wallace
 1858 Papers of Darwin &
Wallace read
 1859 Publishes his work
1.
VARIATIONS exist in individuals within a species
(caused by mutations/genetic recombination). Those
with favorable variations have an advantage for
survival.
Live Longer > Produce more offspring > Genes passed on
2.
3.
4.
OVERPRODUCTION of offspring: More offspring are
produced than can survive, but the population remains
fairly constant.
STRUGGLE FOR EXISTENCE: Competition for food,
space, mates (limiting factors).
NATURAL SELECTION –the best adapted are ‘selected’.
Survival of the Fittest = best suited for the
environment
Darwin’s Fittest = Differential Reproductive Success
*HW Ch 18
DESCENT OF MODIFICATION: Similarities in
related species are due to common ancestry
Idea of ‘common descent’ was inspired by
BIOGEOGRAPHY (geographical distribution of
species)
Natural Selection favors Reproductive Success of
certain individuals over others in a population.
Individuals do not evolve, populations do
The study of the past and present geographic
distribution of organisms.
DARWIN: Species found on ocean islands tend
to resemble species of the nearest mainland,
even if the environment is different.
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Galapagos (South America)
Cape Verde Island (Africa)
AUSTRALIA: (separate land mass for millions of
years). Has distinctive organisms not found
anywhere else in the world even though climate
is the same.
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Monotremes: Marsupials
HHMS-Mice Natural Selection
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Review timelines lab assignment and
completed timelines in the classroom
◦ NOTE: 1 Meter stick = 1 Billion Years
 4.6 Billion (Age of Earth) = ?
 10 cm = ?..........1 cm = ?.........1 mm = 1 million years
DAY 3
Textbook….Ch 21
CAN ALSO BE DEFINED AS:
 Any
change in the frequency of alleles
from one generation to another.
 A change in the gene pool of a population
over time.
 A change in frequencies of alleles in the
gene pool of a population.
Ch 19 -text
MICROEVOLUTION:
• Genes Mutate
• Individuals are selected
• Populations evolve
MACROEVOLUTION:
• LARGE changes, as when new species
are formed.
• Can SEE the changes
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The study of genetic variability within a
population and the evolutionary forces
that act on it.
Distinguishes genetic equilibrium* from
evolutionary change
(*relates to the HARDY-WIENBERG
PRINCIPLE; ‘population is at
equilibrium’)
(Pop. Genetics Handout, slides)
1.
2.
3.
4.
5.
Genetic Drift – due to chance; relates to size of
the population; causes a decrease in variation
within the population; Ex- Bottleneck effect;
founder effect
Gene Flow – relates to isolation; increases
variation within a population;
Ex- Immigration/Emigration
Mutation – substitution of alleles
Non-random mating – Ex- Inbreeding (selfpollinating plants); assortive mating (like:like)
Natural Selection – differential success in
reproduction; only cause likely to be adaptive.
*(These are the ANTITHESIS of H-W conditions)
Genetic Drift:
random
1
Evolutionary Fitness- The number of
surviving offspring left to produce the next
generation; measure of evolutionary success
4
Gene flow: random migration
2
Genetic Shuffling; Non-random* Mating
5
Mutation:
random
3
Variation ~ Differential Reprod. ~ Heredity
Adaptive; Not Random
http://evolution.berkeley.edu
• Explain the increased frequency of dark moths during the 1880’s in Britain.
• Explain the decreased frequency of dark (melanic) moths from 1960’s to 80’s
• Other ways humans have had an impact on variation in other species (or our own)?
This definition of evolution was developed
largely as a result of independent work in the
early 20th century by Godfrey Hardy, an English
mathematician, and Wilhelm Weinberg, a German
physician.
Through mathematical modeling based on
Weinberg
Hardy
probability, they concluded in 1908 that gene
1862-1937
1877-1947
pool frequencies are inherently stable but that
 The mathematical
prediction
frequencies
evolution should
be expectedthat
in all allele
populations
virtually all of the time. They resolved this
do not change
in a
apparentfrom
paradoxgeneration
by analyzing theto
netgeneration
effects of
potential evolutionary
mechanisms.of microlarge population
in the absence
evolutionary
processes
genetic drift, etc.)
Essentially,
went from (mutation,
Punnett Square/Mendelian

predictions of the probability of specific offspring
genotypes based on parental genotypes to determining
Doesexpected
NOT exist
infrequencies
nature, however,
allelic
for entire provides:
populations.
 A means to calculate allelic frequencies
 A baseline for comparison
(non-evolving population to an evolving population)
1.
2.
3.
4.
5.
We have a very large population size
(Handout)
Isolation from other populations exists
(no emigration/immigration)
There are no net mutations
There is random mating; all breed and produce
the same number of offspring
There is no natural selection
HW formula on the AP Equations Handout
• p+q=1
p (dom trait) + q (rec) = 1
• (p + q)2 = p2 + 2pq +q2 = 1
• WHERE: In a population….
p = freq of the Dominant allele
q = freq of the Recessive allele
p2 = freq of individual AA
q2 = freq of individual aa
2pq = freq of individual Aa
Diagram of Hardy-Weinberg genotype proportions from male (sperm)
and female (egg) contributions. Given a locus with two alleles
designated A and a that occur with frequencies p and q, the chart
shows the genotype frequencies (p2, 2pq, and q2) as differently colored
areas. Note that the heterozygotes (blue + yellow = green) can be
formed in two different ways.
Albinism is a rare genetically inherited trait that is only expressed in the phenotype of
homozygous recessive individuals (aa). The most characteristic symptom is a marked
deficiency in the skin and hair pigment melanin. This condition can occur among any
human group as well as among other animal species. The average human frequency of
albinism in North America is only about 1 in 20,000.
What have we been given?:
Referring back to the Hardy-Weinberg equation (p² + 2pq + q² = 1), the frequency of
homozygous recessive individuals (aa) in a population is q². Therefore, in North America
the following must be true for albinism:
q² = 1/20,000 = .0005
What can we find out from this information?
By taking the square root of both sides of this equation, we get: (rounded off)
q = .007
In other words, the frequency of the recessive albinism allele (a) is .00707 or ~1 in 140.
With this information, what can we solve for?
Knowing one of the two variables (q) in the Hardy-Weinberg equation, it is easy to solve
for the other (p). P = 1 – q = 1 - .007 = .993
The frequency of the dominant, normal allele (A) is, therefore, .99293 or about 99 in 100.
How can we use this information to determine genotypic frequencies?
p²into
(AA)the=Hardy-Weinberg
98.6% No ‘a’ allele
p² + next
2pq +
q² =is1to plug the frequencies of p and q
The
step
equation:
(.993)² + 2 (.993)(.007) + (.007)² = 1
2pq (Aa) = 1.4% carriers
.986 + .014 + .00005 = 1
q² (aa)
= .005% Albinos
**Given a Phenotype = p2, q2, 2pq
Allele/Gene Frequency = p,q
DAY 3-4
REVIEW WORKSHEETProblems 1-8,10 front, 1-6 back
TEXT p415 1,2 (3)
**QUIZ: Day 5
The types of selection relate to the bell curve. The bell curve is altered due
to forces of nature favoring certain traits over other.
Text p419-21
Day 4
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Clutch size
(amount of eggs
laid) in starlings is
between 3 and 6.
Clutch size is a
genetic trait
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Human Birth Weight: The
optimum birth weight is
the one with the lowest
mortality weight
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Galapagos finches- extended drought, wet periods.
The male widowbird collects females for his “harem” by
attracting them by the length of his tail. The longer the
tail, the more females he attracts and mates with.
Rock Pocket Mouse
HHMI- Rock Pocket Mouse 10.25
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Relatively rare
Galapagos Finches
Male salmon mate at either 2 years old
(Jacks) or 3 yo (hooknoses). Males fight
over who will fertilize the female’s eggs.
The male salmon are either very small or
very large, very few are average size.
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Text p424
Gradual change in genotype and phenotype through a series
of geographically separated populations as a result of an
environmental gradient
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The creation of a new species. Evolution of
a new species when a population becomes
isolated from other members of the species.
Scientists put every living thing in one of 8
different taxonomic groups:
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DOMAIN
KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS
SPECIES
Beak of the Finch 15.54
HUMANS?
REPRODUCTIVE ISOLATING MECHANISMS
Prevention of interbreeding between two different species whose ranges
(habitats) overlap. Most species have two or more mechanisms that block
a chance occurrence of interbreeding between closely related species.
I.
PREZYGOTIC BARRIERS:
 Barriers in place to prevent fertilization/
mating of two different species
1. Temporal isolation
2. Habitat isolation
3. Behavioral Isolation
4. Mechanical Isolation
5. Gametic Isolation
TEXT p430
II. POSTZYGOTIC BARRIERS:
 Functions after fertilization, prevents
development of viable, fertile offspring
1. Reduced Hybrid Viability
2. Hybrid Sterility
3. Hybrid Breakdown
TEXT p430-431
*Preserve genetic integrity of a
species by preventing gene flow
Two species of
garter snakes:
one lives mainly
in water while
the other is
mainly
terrestrial.
The eastern
spotted skunk
mates in late
winter; the
western spotted
skunk mates in
late summer.
http://bio1151b.nicerweb.net/Locked/media/ch24/
Blue-footed
boobies of the
Galapagos
perform a
courtship display
unique to the
species. Boobies:
These 2 species
of snails have
opposite spirals
in their shells so
their genital
openings are
not aligned.
Gametes of red
and purple sea
urchins are
released into
the water, but
are unable to
fuse.
Some salamander
subspecies of the
genus Ensatina can
hybridize, but hybrids
do not complete
development or are
frail.
A mule is the
robust but
sterile hybrid
between a male
donkey and a
female horse.
Hybrids of two
rice strains are
vigorous and
fertile, but the
next
generation
(center) may
I.
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Allopatric Speciation:
“Different /native land”
Subpopulation becomes physically separated
from the original population…how?
1.
2.
3.
4.
Mountains emerge
Glaciers migrating
Land Bridges Develop
Rivers Shift
*Most Common Method of
speciation, especially in
animals
TEXT p433
II.
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Sympatric Speciation: “Together/native land”
New species develops in the same geographic
region as the parent population
◦ **Common in Plants
◦ Polyploidy (2 or more chromosome sets)
◦ Allopolyploidy (interspecific hybrid- multiple
sets of chromosomes from 2 or more species)
*Can occur in animals, but how is
TEXT p435, fig 20-9
debated. (Not due to polyploidy)
1.
2.
3.
New species may not compete successfully
with parent species; goes extinct
New species may co-exist with the parent
species
New species may outcompete parent species;
hybrid may replace the parent(s)
TEXT p436, fig 20-10
Lizards in an evolutionary
tree 17.45
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Geographic Isolation
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Kaibab Squirrels- Gr.Canyon
Common in plants; change
in ploidy (# chromosomes)
and ecology 80% of all
flowering plants- polyploids
hybridization
I. Gradualism:
Continuous over long
periods of time;
gradual accumulation
of adaptive
characteristics
2. Punctuated
Equilibrium
long periods of stasis
interrupted by short*
periods of rapid
speciation (*’short’may
be thousands of years)
*
TEXT p438
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Large-scale phenotype in populations warrant
their placement in taxonomic groups at the
species level and higher.
Dramatic evolutionary changes that occur over
long time spans.
Dominated by multiple microevolutionary
processes or external, chance events…or both?
Important Aspects of Macroevolution:
1. Appearance of evolutionary novelties
2. Adaptive Radiation
3. Mass Extinction
Also related:
4. Earth’s Geological History
Ch 20 p439
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Huge differences in phenotype leading to different
taxonomic groups. Comes from pre-existing
structures….examples?
Jointed appendages, feathers
Originate from modifications of pre-existing
structures
May be due to:
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Changes in control/regulatory genes (on/off switch)
Preadaptions (changed from one role/repurposed)
Changes in Allometric Growth “different measure”
Paedomorphosis “child form”
Epigenetics 1.47
Epigenetics and Gene
Expression utah.edu
Due to
Allometric
Growth
Varied rates of
growth for different
body parts
Examples…
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(Text p440)
sunfish
Skull
Fiddler crab
T Rex
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When juvenile
characteristics are
retained into the adult
stage
This is an example of
varied changes in
timing of development
Text p 440
The
evolutionary
diversification
of many related
species from
one or a few
ancestral
species in a
relatively short
period.
Adaptive
zones- new
ecological
opportunities.
*Divergent
Evolution
Opening of
‘adaptive
zones’ –
allowed for
new species
to develop
http://www.biozoomer.com/2011/03/speciation-in-organic-evolution.html

“The Descent of Man”
Darwin, 1871human and apes
shared a common
ancestry
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Taxonomy
◦ 3 Domains
◦ 6 Kingdoms
3 Domains:
Bacteria /Eubacteria
Archaea
Eukaryota
Classification of
a Leopard
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo

Homo sapiens

(Man) (thinking)
Sapiens
Anthropoids:
Monkeys, Apes, Humans
~45mya Africa/Asia
Hominoids:
Apes, Humans
~23-25 mya
Hominids:
Humans & ancestors
~6-7mya
P
R
O
S
I
M
I
A
N
S
PROSIMIANS
“MISSING LINK"
FOUND: New
Fossil Links
Humans,
Lemurs?
47mya
“Ida”
Prosimian-Monkey Link
2009
Most Profound
-Ability
to walk upright
Evolutionary
Novelty?
-6mya
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Advanced brain
Eyes forward- stereoscopic vision/depth perception
Color vision
Acute hearing
Dental formula- same #, type, arrangement of teeth
Long slender limbs/rotate freely at hips/shoulders
5 flexible digits with flattened nails/not claws
Opposable thumbs
Complex social behaviors
Usually 1 offspring at a time; longer parental care
Shape of the Spine, Pelvis
Foramen magnum position
Leg vs arm length
Alignment of great toe
Skull: brain, brow, jaw
and teeth
“Lucy”- 1974
*locking knee
“Handy Human”,Tools
Migration