Transcript Wed. 3/11 Evolution

Warm Up
• What do you think evolution means?
Evolution
The History of Life
The Record of Life
History in Rocks
• FOSSILS
• Any evidence of life from the past
– A trace of a long-dead organism (most are
hard parts such as bones, teeth, shells,
and woody stems.
Where are fossils found?
1. Sedimentary rock layers (strata)
(Grand Canyon, AZ)
2. Frozen in Ice
(wooly mammoth)
3. Stuck in tree sap or Amber
(insects)
4. Stuck in Tar
(Saber Toothed Tigers)
Fossils are not always body
parts but:
• Imprints- a film of
carbon remains after
an organism decays
• Mold- an imprint or
impression in a rock of
the shape or track of an
organism
• Cast- when
sediments or hard
minerals fill in a
cavity left by a fossil
mold
• Replacement- when
sediments or hard
minerals replace the
whole organism.
ex. petrified wood
Scientists Who Study Fossils…
The Age of Fossils
• Relative Age (relative dating)
the fossil’s age compared or
related to another fossil.
(sequence of age)
• Absolute Age- numerical age
• Journal: Give an example of
relative age and absolute age
Radiometric Dating
• The age of fossils can be determined by
measuring the amount of a particular isotope
it contains. This quantity is then compared
with the amount of some other substance in
the fossil that remains constant over time.
• Carbon 14 -------------> Carbon 12
What is the half life of Carbon-14?
Half life = amount of time for half of the substance to decay.
The Geologic Time Scale
A time scale for the
history of the Earth
*** I do not test you on eras,
periods, or events***
Journal: What is the difference
between a hypothesis, a
theory, and a law?
The Theory of Evolution
• All the changes that have formed life on
earth from its earliest beginnings to the
diversity that characterizes today.
Evidence used to support
Evolution
• Fossils
• Structure of Organisms
– Anatomy & Physiology
• Embryology
• Biochemistry
The Fossil Record
• Fossil-bearing strata show that species of
organisms appear, existed for a while, and
then disappear or became extinct
• The fossil record indicates that there were
several mass extinctions,
– brief periods during which large numbers of
species disappeared
– e.g trilobites disappeared during the Permian
extinction 245 million years ago.
Geology in the 1800’s
George Cuvier (1769-1875)
French Anatomist
Catastrophismsudden geologic catastrophes caused
the extinction of large groups of animal
at certain points in the past.
Geology in the 1800’s
• Charles Lyell (1797-1875)
• English Geologist
• Uniformitarianism
Geologic processes have changed the
shape of the earth’s surface in the past and
continue to work in the same ways today
Jean Lamarck
• French Scientist (1744-1829)
• Proposed that similar species
descended from a common ancestor
• To explain how species changed he
hypothesized that acquired traits could
be passed onto offspring
Acquired Traits
• Something that you gain in your
lifetime….
– Journal: List some examples that you can
think of…
Jean Lamarck
• His hypothesis was fiercely attacked
and easily disproved
• But, he was the first to clearly state that
types of organisms changed over time
and that similar types of organisms are
modified descendents of older types.
Charles Darwin
An English Naturalist (1809-1882)
• He proposed the hypothesis that
species were modified by
natural selection
Charles Darwin
• He Collected 1000s of samples of biological
specimens and fossils
Darwin’s Theories
1. Descent with Modification
States that the newer forms appearing in
the fossil record are actually the modified
descendents of older species.
(Describes the process of evolution)
Darwin’s Theories
2. Theory of Natural Selection -Describes the
mechanism or how evolution occurs.
Natural Selection
5 parts:
a) All organisms produce more offspring than can
survive.
b) All organisms within a species vary.
c) Every organism faces a constant struggle to
survive.
d) Organisms best suited for their environment
survive.
e) Organisms that survive pass their traits onto their
offspring.
Example: The bacteria that
causes Ulcers
Antibiotic
Resistance
Figure 3: Mutation rate versus genome size for bacteria and other biological
entities.
From A mutation burst during the acute phase of Helicobacter pylori infection in humans and rhesus macaques
Bodo Linz, et. al., Nature Communications 5, Article number: 4165
Darwin’s Theories
• The resulting change in the genetic
makeup of a population is Evolution.
• In an evolving population, a single
organism’s genetic contribution to the
next generation is termed Fitness.
Favorable Traits
• The environment “selects” the traits that
will increase a population. The kinds of
traits that are favorable depend on the
demands of the environment.
Journal: Write down an example where
the environment favors one trait over
another.
• A favorable trait is known as an
adaptation or it gives an organism an
adaptive advantage.
Example: In an environment
that is dark, the dark ducks
survive better
Create Your Own Natural
Selection Diagram
• Begin In Class
– Due Next Class!!!
a) All organisms produce more offspring than can
survive.
b) All organisms within a species vary.
c) Every organism faces a constant struggle to
survive.
d) Organisms best suited for their environment
survive.
e) Organisms that survive pass their traits onto their
offspring.