EVOLUTION BY
MEANS OF NATURAL
SELECTION
Ch. 10 & 15
1. What adaptations does this organism
have?
2. How did these adaptations evolve?
3. How do they enable the organism to
survive in its environment?
1. What adaptations does this organism
have?
2. How did these adaptations evolve?
3. How do they enable the organism to
survive in its environment?
1. What adaptations does this organism
have?
2. How did these adaptations evolve?
3. How do they enable the organism to
survive in its environment?
They have long legs and neck,
long, tough, prehensile tongue,
and leathery mouth for food
gathering. Their coloration is
protective. They are tall with
good eyesight for watchfulness.
Giraffes have high blood
pressure (240/160) for pumping
blood to the brain. Long neck
for reaching its food source
(leaves)
The Peppered Moth
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2 variations of Moths: light and dark
Prior to the industrial revolution – white
was favored
Post-industrial revolution – black
(peppered) became more common.
Why? How do predators and
environments drive evolution?
The Industrial Revolution
polluted the environment,
raining soot down on the
countryside. As a result,
white moths became highly
visible on the now blackened
tree trunks. Black moths such
as the peppered moth (which
had previously been quite
rare), suddenly had a
competitive advantage. They
were well camouflaged on
black tree trunks, and their
numbers grew exponentially.
By the early twentieth
century, they were the
dominant moth form in
polluted areas of the UK.
EVOLUTION BY
MEANS OF NATURAL
SELECTION
5 Principles
1. Variation
 All
species have variations
 Variation is the raw material for
natural selection
Ex: Variations in giraffes
2. Struggle for Existence

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Organisms produce more offspring than
can survive.
The environment produces struggles
organisms must surpass to
survive
3. Only some survive to
reproduce

Some are better able to survive and
reproduce (pass on their genes)
4. Natural selection results in
genetic change


Each generation contains an increased
proportion of individuals with traits that
promote survival and reproduction.
What are some alleles that a successful
giraffe might have?
Neck length
 Leg length

5. Species adapt to their
environment

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Selection makes a population better suited
to it’s environment.
The environment determines
the direction of genetic change.
What drives the Natural Selection?
*When
 is a
mutation
 a ‘good’
mutation?

Mimicry
and
Coloration
Driving Force of Evolution:
Competition



Limiting factors – any condition of the
environment that limits the size of a population
Carrying capacity – The number of organisms
that can be supported by a particular ecosystem
Overpopulation - the condition of having a
population so dense as to cause environmental
deterioration, an impaired quality of life, or a
population crash
Rapid,
RAPID
Slow or
GROWTH
Negative Population
“Pyramid”
Growth?
SLOW GROWTH “Boxy”
“Pear Shaped”
“Middle Bulge”
Rapid, Slow or Negative Population Growth?
Slow vs Fast
Which is Fast, which is Slow Growth?
Fast -1930 to Negative 1999
Rapid, Slow or Negative Population Growth?
Symbiosis
A close, long-term association between two or
more species.
3 types:
Mutualism – all participating organisms
benefit
 Commensalism – one species benefits, the
other is unharmed
 Parasitism – one species benefits, the other
is harmed (usually not killed – why?)

Factors Affecting Population
Changes
Birth Rate
 Death Rate
*usually determine the size of the base, but
also affected by Migration
 Immigration- movement INTO a
population (migrant workers/child bearing
age)
 Emigration- movement OUT of a
population

Evidence of Evolution

Fossils

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Bones, casts, footprints, amber, ice
Homologous structures
Comparative embryology
Vestigial structures
Biochemical (DNA and amino acids)
200,000- Homo Sapiens (11:59:30)
Land
Plants,
Animals
~3.5
Bill yrs
Oldest
fossils/p
rok
Cyanobacteria
Endosymbiosis
Primate Evolutionary Tree
Evolutionary Timelines

Review timelines lab assignment and
completed timelines in the classroom

NOTE: 1 Meter stick = 1 Billion Years


LAB:
4.6 Billion (Age of Earth) = ?
10 cm = ?..........1 cm = ?.........1 mm = 1 million years
Textbook…
Mass
Extinction
Opening of
‘adaptive
zones’ –
allowed for
new species
to develop
Earth’s Geologic
History
Classification of
a Leopard
Anthropoids:
Monkeys, Apes, Humans
~45mya Africa/Asia
Hominoids:
Apes, Humans
~23-25 mya
Hominids:
Humans & ancestors
~6-7mya
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Characteristics of Primates
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
Human Evolution:
Australopithecines
Homo erectus
Homo habilis
Homo sapiens
The remains or evidence of any creature or
plant that once lived on the Earth.
Fossils


Fossils are often found in sedimentary rock, which is formed
from layers of silt and sand covering dead organisms.
The oldest are found on the lowest layers, youngest in the
upper layers
Fossils in Amber
(Hardened Tree Sap)
Homologous Structures
Similar structure and
anatomical position
(but not necessarily
the same function) in
different organisms
suggesting a common
ancestry or
evolutionary origin
(e.g. wings of bats and arms of humans are homologous).
How Many Neck Vertebrae?
Comparative Embryology
the more closely related any two species are,
the more similar their development
Vestigial Structures
structures or organs that seem
to serve no useful function
Organisms having vestigial structures probably share a
common ancestry with organisms in which the
homologous structure is functional
Biochemical/DNA Evidence

The closer the DNA sequences of 2
organisms are, the more closely related
they are.
 Ex. Humans and chimps have DNA that
is 99% identical
Dating the Age of Fossils

Carbon-14 dating is a way of determining
the age of certain archeological artifacts of
a biological origin up to about 60,000
years old. It is used in dating things such
as bone, cloth, wood and plant fibers that
were created in the relatively recent past
by human activities.
This Carbon 14
combines with
oxygen to form
carbon dioxide,
which plants take
in during
photosynthesis
Animals and People eat the plants and take
in the C14. We have a set amount of C12 in us,
but the amount of C14 changes while we live.
Once we die, the
amount of C14
decreases (by half
in 5,700 years!!)
but the amount of
C12 in us stays
constant (It is a
STABLE isotope).
So the RATIO C14
to C12 changes
C14 can be used
to date any fossil
up to about
60,000 years
old…why the
limit?
Driving Force of Evolution:
Competition



Limiting factors – any condition of the
environment that limits the size of a population
Carrying capacity – The number of organisms
that can be supported by a particular ecosystem
Overpopulation - the condition of having a
population so dense as to cause environmental
deterioration, an impaired quality of life, or a
population crash
3. Mass
Extinction
Opening of
‘adaptive
zones’ –
allowed for
new species
to develop
4. Earth’s
Geologic History
6th Mass Extinction

Mass Extinction Event – YouTube 9.19

Permian Mass Extinction

Permian Methane Explosion
5.06
5.56