Download 10.3 - Theory of Natural Selection

13.1 Ecologists Study Relationships
Agenda – 04.29.2015
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Warm-up
10.3 Reading Preview and Bioterms
10.3 Notes
The Making of the Fittest
10.3 Theory of Natural Selection
Warm - up
• Tell me what you know about Natural Selection
When you are done start working on 10.3 reading preview
10.3 Theory of Natural Selection
OBJECTIVES
• Compare artificial selection to natural selection
• Examine the factors Darwin considered in forming his
theory of natural selection
• Summarize the four principles of natural selection
10.3 Theory of Natural Selection
KEY CONCEPT
Darwin proposed natural selection as a mechanism for
evolution.
10.3 Theory of Natural Selection
Vocabulary
• Artificial Selection – process by which humans modify a
species by breeding it for certain traits (304)
• Heritability – ability of a trait to be passed from one
generation to the next (304).
• Natural selection – mechanism by which individuals that
have inherited beneficial adaptations produce more
offspring on average than do other individuals (305).
• Population – all of the individuals of a species that live in
the same area (306).
• Fitness – measure of an organism’s ability to survive and
produce offspring relative to other members of a
population (307).
10.3 Theory of Natural Selection
Who Developed the Theory of Evolution by Natural
Selection?
• Charles Darwin
• His observations:
– Variation: The difference in the physical
traits of an individual from those of other
individuals in a group.
– Adaptation: The features that allow an
organism to better survive in its
environment
Example: The different beak types of different Galapagos finch species.
− Fossils: found evidence of species changing over time
which lead him to believe Earth was much more than
6000 years old.
10.3 Theory of Natural Selection
Several key insights led to Darwin’s idea for natural
selection.
• Darwin noticed a lot of variation in domesticated plants
and animals.
• Artificial selection is the process by which humans
select traits through breeding.
neck feathers
crop
tail feathers
10.3 Theory of Natural Selection
• Natural selection is a mechanism by which individuals
that have inherited beneficial adaptations produce more
offspring on average than do other individuals.
• Heritability is the ability of a trait to be passed down.
• Darwin proposed that adaptations arose over many
generations.
Artificial Selection
• Imposed by humans
• Selective breeding
• Does not improve
fitness
• Genetic modification
• Ex: dog breeds
Natural Selection
•
•
•
•
Diversity
Variation
Heritable
Driven by natural
processes/environment
10.3 Theory of Natural Selection
•There is a struggle for survival due to overpopulation and
limited resources.
•A Population is all the individuals of a species that live in
an area.
•Example: All crows that are around Orange Glen High
School. (ON THE NEXT PAGE)
10.3 Theory of Natural Selection
Natural selection explains how evolution can occur.
• There are four main principles to the theory of natural
selection.
– variation
– overproduction
– adaptation
– descent with modification
ADAPTATION
VARIATION
OVERPRODUCTION
DESCENT
with
MODIFICATION
10.3 Theory of Natural Selection
• Fitness is the measure of survival ability and ability to
produce more offspring.
• What if…..
– A bird outcompletes other birds for food in a particular
area and that bird can produce many more eggs, this
bird has a high FITNESS
10.3 Theory of Natural Selection
Natural selection acts on existing variation.
• Natural selection can act only on traits that already exist.
• Structures take on new functions in addition to their
original function.
five digits
wrist bone
10.3 Theory of Natural Selection
Exit Ticket
• In your own words, what is the difference between
Natural Selection and Artificial Selection.
• What did Charles Darwin observe in the world that
helped him to come up with his theory of Natural
Selection?
• List the 4 main principles of Natural Selection