Transcript Evidence For Evolution

Evidence for
Evolution/Common Ancestor
Provides TRANSITIONAL LINKS
between species
FOSSILS
SIMILAR EMBRYONIC
DEVELOPMENT
1. Homologous Structures:
NOTE: similar structure, but NOT
always function!
2. Analogous Structures
NOTE: similar
FUNCTION, but not
STRUCTURE
SIMILAR ANATOMY
Body structure that has no function in a
present day organism but was probably useful
to an ancestor
VESTIGIAL STRUCTURES
Biochemical Evidence
(Similar DNA)
Almost all living things use the same
biochemical molecules such as………
DNA, Protein, ATP
WHAT IS
EVOLUTION???
WHAT CAN CAUSE
EVOLUTION???
Mechanisms/Causes of
Evolution Notes
NATURAL SELECTION
MUTATIONS
WHAT’S GOING ON HERE?
o
r
GENE FLOW
WHAT DOES THIS EVEN MEAN
I CAN MATE
WITH ONE OF
YOU. I WILL
DECIDE!!!
NON-RANDOM MATING/SEXUAL
SELECTION
Mechanisms/causes of Evolution
Natural Selection
Mutations
Gene Flow
Non Random Mating: Sexual Selection
But Wait… There is one more
agent
Genetic Drift
Refers to changes in the population due to chance
(random)
Not due to natural selection
Natural Selection vs. Genetic Drift
Genetic Drift
Population Before
After
Disaster Occurs
Population
Types of Genetic Drift
1.Bottleneck Effect
2. Founder Effect
Bottleneck Effect
a. Occurs when an event causes a significant
percentage of the population or species to be killed
or otherwise prevented from reproducing
b. Often caused by natural disasters or human
interference
Bottleneck Effect Model
Founder Effect
Occurs when a few individuals found a colony and only a
fraction of the total genetic diversity of the original
population is represented.
Founder Effect
Founder Effect
Example: Amish population
Isolated religious sect that descended from a few German
ancestors. As many as 1 out of every 14 people carry a recessive
allele for unusual form of dwarfism and/or allele for polydactylism
(extra fingers)
In non-Amish population, only 1 in 1,000 has this
allele
Let’s Practice a Few.
What term would best describe the picture below?
25%
25%
25%
25%
1.
2.
3.
4.
Founder Effect
Bottleneck Effect
Mutation
I need help with this.
Original
Population
Newly
Established
Population
What term would best describe the picture
below?
25%
25%
25%
25%
1.
2.
3.
4.
Founder effect
Bottleneck effect
Natural selection
I need help with this.
What mechanism of evolution is
shown below?
1. Genetic Drift
2. Gene Flow
3. Mutation
4. Natural
Selection
25%
1.
25%
2.
25%
3.
25%
4.
What Mechanism of Evolution is shown below?
25%
25%
25%
25%
1.
2.
3.
4.
Genetic Drift
Gene Flow
Natural Selection
Mutation
In reality, are these
conditions achieved in
populations?
NO
So, what do populations actually “do” over
time??
EVOLVE
Is it possible to detect these changes in
a population over a short period of
time?
YES
Hardy-Weinberg provides the
evidence!
Discuss with your
partner the relationship
between the terms…
allele, genotype, and
phenotype,
homozygous, and
heterozygous.
What is a Gene Pool?