Download THE THEORY OF EVOLUTION

THE THEORY OF
EVOLUTION
I. Why do organisms evolve?

Organisms evolve in order to survive and
continue their species.
II. The Survival Formula
1.
2.
3.
4.
5.
Receive genetic instructions from your
parents.
Compete for necessary resources.
The most fit survive and reproduce.
Populations accumulate adaptive
mutations.
Survival genes are transmitted to the
next generation.
III. Who was Charles Darwin?
English scientist who
came up with some of
the modern theories
of evolution.
 Lived 1809-1882.
 Sailed on the HMS
Beagle.
 Sailed to South
America and the
South Pacific.

Darwin Continued
Darwin observed and collected many
different species of organisms on his many
stops.
 He observed different species of animals
and plants that were unique to the
islands, but similar to other species he
found on other islands.
 He wanted to figure out why…?

Darwin hypothesized there was a force in
nature that allowed for variation in
populations.
 He called it “natural selection.”
-a mechanism for change in
populations.
-It occurs when organisms with certain
variations survive, reproduce, and pass
their variations to the next generation.
 KNOWN AS: Survival Of The Fittest!

IV. How do we know evolution occurs?
1.
2.
3.
4.
5.
6.
Fossils
Mimicry
Camouflage
Anatomy
Embryology
Biochemistry
Fossils

Fossils are important
because they provide
an actual record of
life and evolutionary
history.
Mimicry

Adaptation that allows
one species to
resemble another
species over time.
Camouflage

Adaptation that allows
a species to blend in
with its surrounding
environment.
Anatomy
Structural features
with a common
evolutionary origin
are called
homologous
structures.
 Vestigial Structures –
body structures with
no function in present
day organisms.

Embryology

Organisms may look
the same in the
earliest stages of
growth.
Biochemistry

Scientists compare DNA and RNA of
different species to see if there are any
evolutionary links.
V. How do new species come into
existence? (Speciation)
1. Gradualism – slow, lingering step by step
process.
2. Punctuated Equilibrium – occurs rapidly
in spurts, normally after a major event.
3. Geographic Isolation – occurs when a
physical barrier divides a population.
4. Reproductive Isolation – when
organisms can no longer breed within the
same species.
VI. Patterns of Evolution
 Adaptive Radiation – when an ancestral
species evolves into an array of species
to fit a number of diverse habitats.
 Divergent Evolution – species that were
once similar diverge, or become
distinctly different.
 Convergent Evolution – species that
were once different are now similar.
VII. Selection Types
1. Stabilizing selection -- Type of selection
that favors the average individuals.
2. Directional selection -- Favors one
extreme variation of a trait & can lead to
rapid evolution.
3. Disruptive selection – Favors both
extreme variations of a trait & can lead to
rapid evolution into 2 species.
Speciation – members of similar
populations no longer interbreed to
produce fertile offspring.