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With the help of this presentation, you would be able to know about
1. Evolution & Natural Selection.
2. 4 steps of Natural Selection, giving an example of each.
3. Explain the importance of "Variation".
4. Does Natural Selection act on an organism's phenotype or genotype?
5. 5 pieces of evidence that support the Theory of Evolution.
1.
Darwin & Natural
Selection
Unit 6: Evolution
Chapter 15
2.
Learning Goals
1. Define "Evolution" & "Natural Selection".
2. Describe the 4 steps of Natural Selection,
giving an example of each.
3. Explain the importance of "Variation".
4. Does Natural Selection act on an
organism phenotype or genotoype? Explain!
5. List the 5 evidences that support the
Theory of Evolution.
3.
Theory of Evolution
Evolution
Evolution: The process of change
over time
Specifically, a change in the frequency
of a gene or allele in a population over
time
4.
Charles Darwin
Father of Evolution
Proposed a mechanism for
evolution, natural selection
Darwin went on a 5-year trip
around the world on the ship,
the HMS Beagle
As the ship’s naturalist, he
made observations of
organisms in South America
and the Galapagos Islands
•Wrote a book, “Origin of the Species”
7.
Natural Selection
Natural Selection: Organisms that are
best adapted to an environment survive
and reproduce more than others
8.
Darwin’s Theory of Evolution occurs
in four steps:
Overproduction (overpopulation)
Competition
Variation
Survival
9.
1. Overproduction:Potential
Overproduction:
for a species to increase in
Each species produces more
offspring that can survive
10.
Negative: having a population so dense
as to cause environmental deterioration,
an impaired quality of life, or a
population crash.
Positive: still large enough population
and genetic diversity (variation).
11.
2. Variation: New genetic
variation within a species
Each individual has a
unique combination of
inherited traits.
Adaptation: an inherited
trait that increases an
organism’s chances of
survival
12.
Inheritance - The process of genetic
transmission of characteristics from
parent or ancestor to offspring.
Ex. Traits such as eye color, height, hair
color, etc.
13.
What adaptations do you see?
14.
What adaptations do you see?
15.
What causes members of the
same species to be different
from one another?
GENETIC VARIATION!
18.
Why is Variation
Because the environment changes.
The more variation within a species,
species the
more likely it will survive
Ex: If everyone is the same, they are all
vulnerable to the same environmental
changes or diseases
The more variation of types of species in
an habitat, the more likely at least some
will survive
Ex: Dinosaurs replaced by mammals
19.
Artificial Selection
Nature provides the variations, humans
select those they find useful
“Selective Breeding” ex. Cow milk
Plant and animal breeders
20.
• Speciation - Evolutionary process by which
new biological species arise
Species - Similar characteristics and can breed
and produce fertile offspring
Can occur as a result of natural or artificial
selection
21.
3. Competition:
competition for limited
resources
Individuals COMPETE for limited
resources:
Food, water, space, mates
Natural selection occurs through
“Survival of the fittest”
fittest
Fitness:
Fitness the ability to survive and reproduce
Not all individuals survive to adulthood
22.
4. Survival: Proliferation of those
organisms that are better able to survive and
reproduce in the environment
The individuals with the best traits /
adaptations will survive and have the
opportunity to pass on it’s traits to
offspring.
Natural selection acts on the phenotype
(physical appearance), not the genotype
(genetic makeup)
Ex: When a predator finds its prey, it is due to the prey’s
physical characteristics, like color or slow speed, not the
alleles (BB, Bb)
23.
Individuals with traits that are not
well suited to their environment
either die or leave few offspring.
Evolution occurs when good traits
build up in a population over many
generations and bad traits are
eliminated by the death of the
individuals.
individuals
24.
Fitness - the genetic contribution of an
individual to the next generation's gene
pool relative to the average for the
population, usually measured by the
number of offspring that survive to
reproductive age.
29.
Peppered Moth A
Which moth will the bird catch?
B
30.
Stop Point – Natural Selection
http://www.hhmi.org/biointeractive/maki
ng-fittest-natural-selection-and-adaptati
on
31.
Descent with
Descent with Modification – each
living species has descended, with
changes, from other species over
time.
Common Descent – all living
organisms are related to one another
33.
Evidence for Evolution:
Fossil Record
Homologous Body Structures
Vestigial Organs
Embryology
Biochemical Evidence
34.
The Fossil Record
Fossils:
Fossils a record of the history of life
on Earth
35.
Missing link between
reptiles and birds
37.
Homologous Body
Homologous
Body Structures:
Structures
similar anatomy in
different types of
animals because
of common
ancestor
39.
Vestigial Organs
Vestigial Organs: “leftover” traces of
evolution that serve no purpose
41.
Embryology:
Embryology embryos of all
vertebrates are very similar early on
43.
Biochemical Evidence
Biochemistry:
Biochemistry DNA with more similar
sequences suggest species are more
closely related
EX: Humans and chimpanzees share
more than 98% of identical DNA
sequences
44.
Learning Goals
1. Define "Evolution" & "Natural Selection".
2. Describe the 4 steps of Natural Selection,
giving an example of each.
3. Explain the importance of "Variation".
4. Does Natural Selection act on an
organism phenotype or genotoype? Explain!
5. List the 5 evidences that support the
Theory of Evolution.
46.
Coral Snake Milk Snake
(Poisonous) (Not
poisonous)
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