Download Evolution - Garnet Valley School District

Evolution
The Earth has been
home to living things
for about 3.8 billion
years.
Evidence
 Fossils – the remains of once living
organisms preserved in the Earth
 Types


of fossils:
Hard Body parts (such as bones, teeth,
shells)
Imprints in Sedimentary Rock
Which rock layer is the oldest?
Mass Extinction
A
period when large number of species
became extinct at nearly the same time.
 Permian
Era- 225 mya: 90% of marine life
when extinct
 Cretaceous
of dinosaurs
Era – 65 mya. Disappearance
How
did new species arise on
Earth?
Evolution- the change of a
species over a LONG period of
time.
We
know today that the
changes arise from genetic mutations or
variations that are passed down from
generation to generation.
 But
where did this idea come from?
2 Theories of Evolution
1.
Theory of Acquired
Characteristics
 The
idea that a species can “get” a trait
by passing it on to the next generation.
 Lamarck!
Lamarck thought that if an animal
acquired a characteristic during its
lifetime, it could pass it onto its
offspring.
•
Charles Darwin
 Naturalists
who published The
Origin of Species after studying
a variety of species on his voyage.
2. Theory of Natural Selection
Natural
Selection – the best
trait that is suited for the
environment will allow a
species to survive and
reproduce at a higher rate
The Beagle
Darwin’s Voyage
1831-1836
The Galapagos Island
(just read…)
 Darwin was fascinated in particular by the
land tortoises and marine iguanas in the
Galápagos.
 Giant
tortoises varied in predictable ways from
one island to another.
 The
shape of a tortoise's shell could be used to
identify which island a particular tortoise
inhabited.
The Galapagos Islands
 Darwin
collected the preserved
remains of ancient organisms,
called fossils.
 Some
of those fossils resembled
organisms that were still alive today.
The Journey Home
Darwin
Observed that
characteristics of many plants
and animals vary greatly among
the islands
Hypothesis:
Separate species
may have arose from an original
ancestor
Discovery of Genetics?!?!?
Mendel and his peas
• From 1856-63, a monk called Gregor
Mendel cultivated 29,000 pea plants
to investigate how evolution worked
i.e., how characteristics were passed
down the generations.
• He figured out the basic principles of
genetics. He showed that offspring
received characteristics from both
parents, but only the dominant
characteristic trait was expressed.
Mendel’s work only came to light in
1900, long after his death
Four Factors that support Natural
Selection
 Adaptation- trait
 Overproduction –
an abundance of
offspring are
produced, but not all
survive.
 Variation- results
from mutations and
increases the variety
of traits in a species
that allows species to
survive and
reproduce in a
particular
environment.
 Selection –
organisms with
particular
adaptations are most
likely to survive and
reproduce.
Evolution by Natural Selection

The Struggle for Existence-members of each
species have to compete for food, shelter, other
life necessities

Survival of the Fittest-Some individuals better suited
for the environment
Where food was limited, competition meant that
only the fittest would survive.
•
•
This would lead to the natural selection of the best
adapted individuals and eventually the evolution
of a new species.
Welcome to Shark Tank!
Bacho
Size
Sacho
15 feet 20
Macho
Watcho
25 feet 8 feet
feet
# of pups
20
10
30
5
10
9
15
0
20 yrs
10 yrs 15 yrs
fathered
# of pups that
lived to
adulthood
Age
 Which
shark is the fittest?
15 yrs
Natural Selection
 Over
time, natural
selection results in
changes in
inherited
characteristics of a
population. These
changes increase
a species fitness in
its environment
Evidence of Evolution
 Fossilized
Evidence
 Similarities
in Early Embryonic
Development
 Geographic Distribution of Living Things
 Homologous
Body Structures
Fossilized
Evidence
Similarities in Early Development
(look @ colorsheet)
Evidence for Evolution
Vestigial
organs - physical
structures that were fully
developed and functional in an
ancestral group of organisms, but is
reduced and unused in the later
species.
So
basically… organs that serve no
useful function in an organism
i.e.) appendix, miniature legs, arms
Homologous Structures
 Similar
structures that are related species
have inherited from a common ancestor.
 Ex-
the bones in a bird’s wing, dolphin’s
flipper, dog’s leg, human’s arm
GENETIC EVIDENCE!!!
Works Cited

http://www.pbs.org/wgbh/evolution/change/fami
ly/index.html

http://www.ucmp.berkeley.edu/education/explor
ations/tours/Trex/index.html


What did T-Rex taste like?
http://www.thebrights.net/images/TeacherRequest%20Form.pdf

http://www.nclark.net/Evolution#Activities
Activity
Natural Selection in the Peppered Moth