Download The Origin of Species

Chapter 22: Descent with Modification
Objectives
1.
Understand Darwin’s
general observations
2.
Define Evolution
3.
Understand how descent
with modification explains
adaptations of organisms
and unity and diversity of
life.
4.
Understand how
observations (evidence)
has contributed to the
theory of evolution.
Darwin’s work was based on other scientist’s work
-Geology
-Life Sciences
-Classification
-Paleontology
-Population
Darwin’s Trip
-Traveled on a ship called the Beagle around South America
-Darwin studied Geology and inferred current data didn’t support a
static, young earth
-Studied geographic distribution of species
-Main focus was on species adaptation - Characteristics that
enhance species’ survival and reproduction in a specific
environments.
Darwin observed
beak differences
based on the
bird’s major food
source.
Darwin wrote an essay but didn’t
publish
When he realized others were
following his research he decided
to finish and publish “The Origin of
Species”
Artificial and Natural
Selection
-Darwin used the word selection
-Darwin related nature to selective
breeding of plants and animals or
artificial selection
Darwin’s Observations that led
him to the idea of natural selection
1.
2.
3.
4.
Organisms within a population
have variation of traits
Traits are inherited
Species are capable of over
producing offspring
Many offspring don’t survive
Darwin’s Inferences from observations
1.
Individuals whose inherited traits give
them a better chance of surviving and
reproducing in a given environment
leave more offspring
2.
This unequal ability to survive and
reproduce leads to an accumulation of
favorable (selected) traits over
generations.
Natural Selection Summary
p. 460
-Natural Selection was the first
mechanism of evolution
-Process in which certain
organisms with certain traits
survive and reproduce at a higher
rate then others
- Over Time the process of
selection can increase the match
between traits and an organism’s
niche
-If an environment changes
selection of new
traits/adaptations may occur with
the possibility of speciation
Key points
1.
2.
3.
Individuals don’t evolve
Only inherited traits are selected
Environments change constantly
and natural selection is constantly
happening
The theory of evolution is based on data
collected from many fields of study.
1.
Direct observations (p. 161 conclusions)
-
2.
Guppies experiment
Viral evolution (HIV)
Bacterial evolution
Geology and Paleontology (fossil
Record)
3.
Anatomy/Embryology (Homology)
-Homologous structures are variations on a similar structuratl theme
-Vestigial structures are remnant structures == Wouldn’t expect with organism’s current niche.
-Homologies are used to create an evolutionary tree -- the closer the organisms are the more
characteristics they share.
-Genetic Homology
4.
Biogeographical
-Distribution of organisms is determined by
geographical separation.
5.
Population Genetics
-Will discuss next chapter (23)
** Evolution is considered a theory due to
the massive amounts of data to
support as well as constant data that
is still to come.
The Farm Fox Experiment
Directions: Read the article and type a one page paper that discusses the following.
1.
Description of domesticated traits that are shared across species.
2.
Description of the hypothesis of the experiment.
3.
Description of how variables were controlled.
4.
Brief description of the results.
5.
Summary of the conclusions made from the experiment
6.
Summary of how the data gained in this experiment contributes to the theory
of evolution.