Download The Idea of Evolution

Evolution
1) Evolution is the change in the frequency of alleles in
a population over time. Over generations theses changes
lead to new types of organisms developed from
preexisting types.
Galapagos
Recent volcanic
origin most of
animal species on
the Galápagos live
nowhere else in
world, but they
resemble species
living on South
American
mainland.
500 miles west of mainland
Unique species
2. Observation #1: Variation
Darwin’s finches

Differences in beaks
 associated with eating different foods
 survival & reproduction of beneficial adaptations to
foods available on islands
Warbler finch
Cactus finch
Woodpecker finch
Sharp-beaked finch
Small insectivorous
tree finch
Large
insectivorous
tree finch
Vegetarian
tree finch
Small ground
finch
Cactus
eater
Insect eaters
Medium
ground finch
Seed eaters
Bud eater
Large
ground finch
Correlation of species to food source
Seed
eaters
Flower
eaters
Insect
eaters
2. Observation #1: Variation
Giant Tortoises
Whoa,
Turtles, too!
Observation #2: Fossil Record
Mylodon (left) Giant ground
sloth (extinct)
Modern sloth (right)
The Distribution of Fossils
 4) The fossil record
shows that the types
and distribution of
organisms on Earth
have changed over
time.
The Fossil Record

5. When fossils are
arranged in the order
of their age, a
continual series of
change is seen, new
changes being added
at each stage.
Transitional Species (Fossils)
6) A transitional fossil is any fossil which gives us
information about a transition from one species to another.
7) Fossils of transitional
species show evidence
of descent with
modification (or that
species have changed
over time).

8) Natural selection is the mechanism for
evolution.
“How Evolution
happens by
Natural Selection”

8) Natural selection is the mechanism for
evolution.
“How Evolution
happens by
Natural Selection”

8) Natural selection is the mechanism for
evolution.
“How Evolution
happens by
Natural Selection”

8) Natural selection is the mechanism for
evolution.
“How Evolution
happens by
Natural Selection”
8. Natural Selection
1.
2.
3.
4.
Overproduction: more offspring than
available resources
Genetic Variation: offspring have
different traits (different gene combos)
Struggle to Survive: compete for
resources
Differential Reproduction: survivors
reproduce and pass on favored genes

Darwin’s Idea
Descent with Modification
9) Descent with Modification is
the idea that organisms can
change over time through a
process called Natural Selection.
Darwin never wrote about how
life originated but how it could
evolve once it’s here.
10. Essence of Darwin’s ideas
(1) Variation exists in natural populations
(2) Many more offspring are born each season than can possibly
survive to maturity
(3) As a result, there is a struggle for existence
- competition
(4) Characteristics beneficial in the struggle
for existence will tend to become more common in the
population, changing the average characteristics of the
population
- adaptations
(5) Over long periods of time, and given a steady input of new variation into a
population, these processes lead to the emergence of new species
Other Evidence of evolution

11) Evidence of evolution can be found by
comparing several kinds of data, including…
○ the fossil record
○ biogeography
○ anatomy and development
○ biological molecules

Evolutionary theories are supported when
several kinds of evidence support similar
conclusions.
Biogeography

12) Biogeography, the study of the locations of
organisms around the world and in time, it
provides evidence of descent with modification.
Anatomy and Physiology

13) Homologous structures- similar body
patterns in different species, shows common
ancestry between these species.
Anatomy and Physiology

14) Analogous structures are similar in
function but have different evolutionary
origins (developed differently).
Organisms with Analogous structures are not
closely related, instead they have developed
similar strategies for survival.
Anatomy and Physiology

15) Vestigial structures are structures that do
not serve a purpose but did in the species’ past.
A species with a vestigial structure probably shares ancestry
with a species that has a functional form of the structure.
Anatomy and Physiology

16) Related species
show similarities in
embryological
development.
Biological Molecules

17) Biological molecules such as RNA, DNA, and
proteins are used by all living organisms,
indicating a common evolutionary history.
DNA 
RNA 
Proteins!
Reflection

Summarize Darwin’s ideas in your own
words and provide an example
Make me proud!