Transcript The Theory of Evolution

A
Do you think
D
these birds are
related? Why
or Why Not?
C
E
B
What do you
think each bird
eats? Why do
you think that?
Change Over Time
Organisms adapt to suit their
environment – they evolve
Who is Darwin?

Charles Darwin is
considered the father of
modern evolutionary theory

Darwin’s 5 year voyage as
the naturalist on the HMS
Beagle helped him develop
the theory of how change
over time occurs
Figure 15–1 Darwin’s Voyage
Section 15-1

They explored South America and the South
Pacific, including the now famous Galapagos
Islands off the coast of South America

They collected samples of fossils and live
specimens for study

The islands had animals that were unique,
but they also had species that were similar to
those on the mainland
– Ex: marine iguanas and tortises
Giant Tortoises of the Galápagos
Islands
Section 15-1
Pinta
Pinta Island
Tower
Marchena
Intermediate shell
Fernandina
James
Santa Cruz
Isabela
Santa Fe
Hood Island
Floreana
Isabela Island
Dome-shaped shell
Hood
Saddle-backed shell
Darwin Presents His Case

Through his observations abroad, he
concluded that natural variations or
differences occur among individuals of a
population
– EX: Galapagos Finches
Natural Selection

What is Natural Selection:
– Organisms with more favorable traits or
variations tend to survive and reproduce;
organisms with less favorable traits are less
likely to survive
2 Main Points of Natural Selection
1.
Struggle for existence: competition for
territory, food, water, and mates
2.
Survival of the fittest: some organisms
are better suited to survive in an
environment as a result of adaptations
- Examples of Adaptations
Mimicry: copying the appearance of other
species
 Camouflage: blending into the
environment
 Adaptations can take millions to hundreds
of years
 Bacteria show adaptations in 50 or less
years

Mimicry
Camouflage
Before the Industrial Revolution, the white
peppered moths were camouflaged better
than the black peppered moth in England.
However, the pollution
caused by the industrial
revolution caused a lot of
the trees around England
to become a black color.
The number of white
moths decreased, where
the number of black
moths increased, this is
population change over
time
Evidence for Change Over Time
1.
Fossils: by using fossils, scientists can
show the sequence of evolution in an
organism
2.
Geography: organisms that are similar
but live in different parts of the world
–
Earth has changed over the last 4.6 billion
years: Pangaea (the super continent)
Figure 15–14 Geographic Distribution
of Living Species
Section 15-3
Beaver
Beaver
NORTH
AMERICA
Muskrat
Muskrat
Beaver and
Muskrat
Coypu
Capybara
Capybara
SOUTH
AMERICA
Coypu
Coypu and
Capybara
Evidence for Evolution
3.
Homologous
Structures:
structures that are
similar and seen in
different species
•
Ex: forelimbs of
humans/bats
Evidence for Evolution
4.
Vestigial Structures: a body structure
that appears to no longer have a
function
•
Ex: appendix in humans, hipbones in
snakes
Vestigial Structures
Evidence for Evolution
5.
Embryology: by studying unborn
organisms, we can see structures in
common during development in different
organisms
Embryology
Embryology
Embryology
6.
Genetic Relationships: DNA comparisons
help establish evolutionary relationships
between different species
Extra Tidbit of Info
Sometimes organisms with close
relationships (like symbiosis) evolve
together in response to each other’s
changes
•
Madagascar orchid and hawk moth
To reach the nectar of this orchid requires a 30
centimeter (eleven inch) proboscis (tongue) to
penetrate the long nectar spur (white arrow).