BIG IDEA 15: DIVERSITY AND
EVOLUTION OF LIVING
ORGANISMS
Description
A. The scientific theory of evolution is the
organizing principle of life science.
B. The scientific theory of evolution is supported by
multiple forms of evidence.
C. Natural selection is a primary mechanism
leading to change over time in organisms.
Benchmark Number & Descriptor
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SC.7.L.15.1
Recognize that fossil evidence is consistent with the scientific theory
of evolution that living things evolved from earlier species.
SC.7.L.15.2
Explore the scientific theory of evolution by recognizing and
explaining ways in which genetic variation and environmental factors
contribute to evolution by natural selection and diversity of
organisms.
SC.7.L.15.3
Explore the scientific theory of evolution by relating how the inability
of a species to adapt within a changing environment may contribute
to the extinction of that species.
WHAT’S THAT?
CHANGE OVER TIME
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Evolution:
 Scientists
have reason to believe that many species of
organisms have changed overtime.
 Evidence of change is found within the Earth’s crust.
FOSSILS
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Evidence of organisms in the past are based on the
following information:
 Fossil
Record
 Geographic Distribution of Living Species
 Homologous Body Structures
 Similarities in Embryology
FOSSILS
Fossil Record
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Helps organize fossils by
their ages and
similarities
Older fossils found may
not be around anymore;
whereas fossils found in
newer layers of Earth’s
crust maybe related to
today’s organisms.
Types of Fossils
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Imprint in a rock of an
organism, leaf, or feather
Cast of an animal track,
shell, etc.
Petrifaction of bone or
wood
Organism frozen in ice
Insects/organisms trapped
in amber
FOSSILS
Relative Dating
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Fossils found in lower
layers of rock are said to
be older than those found
near the surface.
Radiometric Dating
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Comparison of radioactive
and non-radioactive
elements in a rock can
predict age of rock and
the fossil in it.
FOSSILS
GEOGRAPHY
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Similar animals found
in different locations
are said to be the
product of different
lines of descent from
the same ancestors
OTHER EVIDENCE OF EVOLUTION
HOMOLOGOUS STRUCTURES
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Body parts that are similar
in structure and origin
might show a common
ancestor between
organisms.
Example:
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Bird wing, bat wing, and
dolphin flipper each have
about the same number of
bones and blood vessels
OTHER EVIDENCE OF EVOLUTION
VESTIGIAL STRUCTURES
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A body part that still
exists but has no function
for that organism
Past ancestors may have
had a use for these
structures.
Examples:
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Whales have a pelvic
bone but no legs.
OTHER EVIDENCE OF EVOLUTION
EMBRYOLOGY
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The study of how an
organisms embryo
develops
Similarities suggest an
evolutionary relationship.
OTHER EVIDENCE OF EVOLUTION
DNA
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A way to see if organisms are
related is to study their DNA.
Organisms that have similar
DNA are said to have similar
ancestors.
Example:
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Dogs closest relatives are
bears.
All primates may have
evolved from the same
ancestors.
SPEED of EVOLUTION
GRADUALISM
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Steady, slow ongoing
process
Evidence of
intermediate forms of
species exist.
PUNCTUATED EQUILIBRIUM
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Rapid evolution by
mutation
No middle form found
Example:
 Bacteria
 Changes
quickly to
resist medications
KNOWLEDGE CHECK
1.
2.
3.
4.
How are fossils important evidence for the theory
of evolution?
Whose DNA would be closest to matching yours,
your parents, or a first cousin? Why?
List and give an example of three examples of
evolution.
Distinguish between the two speeds of evolution.
KNOWLEDGE CHECK
1.
2.
3.
4.
How are fossils important evidence for the theory of evolution?
They provide evidence of how species have changed over time.
Whose DNA would be closest to matching yours, your parents, or a
first cousin? Why? Your parents because they are your closest
relatives.
List and give an example of three examples of evolution.
Homologous structures: dolphin flipper, bat wing; vestigial
structures: hip bones in snakes; embryology: humans have gill slits
and a tail bone during development.
Distinguish between the two speeds of evolution. Gradualism –
change takes place over time; fossils show intermediate changes.
Punctuated Equilibrium – rapid change, no fossil record, bacteria
WHO WILL BE THE
NEXT SURVIVOR?
IDEAS of EVOLUTION
Jean Baptiste de Lamarck
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1809, created a theory on how species
evolve overtime
He believed offspring receive traits that
their parents develop during their lives.
Traits that were not used by their parents
were lost, and offsprings did not inherit
them.
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Theory of Acquired Characteristics
Example:
If a parent was a weight lifter and gained
large muscles from working out, the offspring
produced would be born with large muscles.
Lamarck’s ideas were rejected.
Lamarck believed that the long necks of giraffes
evolved as generations of giraffes reached for
ever higher leaves.
IDEAS of EVOLUTION
Charles Darwin
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Mid 1800’s, Darwin traveled to the
Galapagos Islands.
Darwin observed that characteristics
of many plants and animals vary
greatly among the islands.
Darwin hypothesized separate
species may have arose from an
original ancestor.
Darwin figures that species with
traits best fitted for their natural
environment survived and were able
to reproduce.
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Theory of Natural Selection
Darwin wondered why so many
different but closely related finches lived
on islands just a few miles apart.
Theory of Natural Selection
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Organisms which are better adapted to their
environment are able to survive and to reproduce.
Main Ideas about Natural Selection:
 Organisms
differ; variation is inherited.
 Organisms produce more offspring than survive.
 Organisms compete for resources.
 Organisms with advantages survive to pass those
advantages to their children.
 Species alive today are descended with modifications
from common ancestors.
Natural Selection
KNOWLEDGE CHECK
1.
2.
Compare Lamarck’s and Darwin’s ideas of
evolution.
Why is reproduction a factor in Natural
Selection?
KNOWLEDGE CHECK
1.
Compare Lamarck’s and Darwin’s ideas of
evolution.
Lamarck – organisms inherit acquired traits.
Darwin – those organisms that survive are able to pass traits
off to their offspring.
2.
Why is reproduction a factor in Natural
Selection?
In order for traits to be passed on, reproduction has to occur.
The more offspring that are produced, the greater the
chance of species survival.
CHANCES of SURVIVAL
SURVIVING
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In order for a species to survive, organisms must
adapt to their environment.
Adaptations can include:
 Adapting
to hunting
 Insecticide resistance
 Competition for mates
 Physical adaptations
 Behavioral adaptations
SURVIVING
Adaptation to Hunting
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Animals of a species
which are hunted for a
specific reason may
become extinct, while
those animals of the
same species who lack
what is wanted will
survive.
AFRICAN ELEPHANTS
These elephants have been hunted for their
Ivory tusks. Today, 15% of African elephants
do not have tusks. More tuskless elephants
have survived and therefore are able to pass
the tuskless trait to offsprings.
Insecticide Resistance
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To help control the insect
population, many insecticides
have been created.
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This is also true for bacteria
and antibiotics.
The bacteria and insects
become resistant and do not
die off and therefore are
able to reproduce and pass
the resistant traits along.
http://en.wikipedia.org/wiki/Pesticide_resis
tance
SURVIVING
Pesticide application can artificially select for
resistant pests. In this diagram, the first generation
happens to have an insect with a heightened
resistance to a pesticide (red). After pesticide
application, its descendants represent a larger
proportion of the population because sensitive
pests (white) have been selectively killed. After
repeated applications, resistant pests may
comprise the majority of the population.
SURVIVING
Competition for Mates
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Survival of individual organisms does
not necessarily mean survival of an
entire species.
Reproduction has to occur in order
for next generations to occur.
Many times, organisms will only mate
with other organisms that have
specific looks.
If an organism does not posses these
certain traits and mating does not
occur, that particular organism may
die out.
SURVIVING
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Leaf Butterflies
Physical Adaptations
Camouflage allows an
animal to blend into its
environment.
Mimicry allows one animal
to look, sound, or act like
another animal to fool
predators into thinking it is
poisonous or dangerous.
2 Bumble
Bees and 2
Robber Flies
SURVIVING
Behavioral Adaptations
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Instinctive Behaviors
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Happen naturally and do not
need to be taught
Examples:
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Migration:
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an animal or group of animals
moving from one region to
another and then back again.
Reasons:
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better climate
better food
safe place to live
safe place to raise young
go back to the place they were
born
EXTINCTION
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If a species cannot
adapt to its
environment, it may
become extinct.
 All
of the organisms of
a specific species must
die in order to become
extinct.
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Extinction may happen
over a long period of
time or in an abrupt
manner.
 Mass
extinctions have
occurred when sudden
changes in climate
happen, such as the ice
age or if a natural
disaster occurs, such as
a volcanic eruption.
EXTINCTION
KNOWLEDGE CHECK
1.
2.
3.
How is the tuskless trait a survival characteristic for
some elephants?
Doctors are beginning to see a problem with
everyone using antibacterial hand soap. Why?
List one physical and one behavioral adaptation.
KNOWLEDGE CHECK
1.
2.
3.
How is the tuskless trait a survival characteristic for
some elephants? Tuskless elephants are less likely to
be hunted; therefore, they will have a better chance to
reproduce.
Doctors are beginning to see a problem with everyone
using antibacterial hand soap. Why? Bacteria are
beginning to become resistant to these soaps since
they are being used in excess.
List one physical and one behavioral adaptation.
Physical – camouflage
Behavioral - migration