Transcript 15-3 - MrKimsClass

15-3 Darwin Presents His Case
Publication of On the Origin of
Species
 15.3 NOTES #1
 Outline the events leading to Darwin’s
theory.

DARWIN RETURNS TO ENGLAND FROM
THE GALAPAGOS IN 1836.

DARWIN CONTEMPLATES HIS IDEAS
AND WRITES HIS MANUSCRIPT.

IN 1858 DARWIN RECIEVES AN ESSAY
FROM ALFRED RUSSEL WALLACE
ABOUT HIS THOUGHTS ON
EVOLUTION.

IN 1859 DARWIN PUBLISHES “ON THE
ORIGIN OF SPECIES”
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Inherited Variation and
Artificial Selection
 Natural variation
 Nature provides differences among
individuals of a species
 Today, we know that heritable variation
in organisms is caused by variations in
genes
 Darwin said this variation mattered
Inherited Variation and
Artificial Selection
 Artificial Selection
 Nature provided the
variation, and humans
selected those variations
that they found useful
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Inherited Variation and
Artificial Selection
 15.3 NOTES #2
 Describe how natural variation is used in
artificial selection.
 NATURE PROVIDES VARIATION.
 HUMANS SELECT THE
VARIATION THEY FIND USEFUL.
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Evolution by Natural Selection
 Fitness
 Darwin said this is the
ability of an individual to
survive and reproduce in its
specific environment
 Adaptation
 Any inherited characteristic
that increases an organism’s
chance of survival
Evolution by Natural Selection
 What is survival of the fittest?
 Can you see the organisms in these photos?
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Evolution by Natural Selection
 Survival of the fittest = Natural selection
 The hunting lioness is hard to see!
 Individuals that are better suited to their environment survive
and reproduce most successfully
 Over time, natural selection results in changes in the
inherited characteristics of a population. These changes
increase a species’ fitness in its environment.
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Evolution by Natural Selection
 15.3 NOTES #3
 Explain how natural selection is related to a
species’ fitness.
 INDIVIDUALS WITH
CHARACTERISTICS/TRAITS
WHICH ARE BEST SUITED FOR
THEIR ENVIRONMENT WILL
SURVIVE AND REPRODUCE.
 THIS IS “SURVIVAL OF THE
FITTEST”
 THESE INDIVIDUALS ARE
NATURALLY SELECTED FOR.
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Evidence of Evolution
 Fossils are fun!
 Darwin argued that living
things have been evolving on
Earth for millions of years.
 Evidence for this process
could be found in the fossil
record, the geographical
distribution of living species,
homologous structures or
living organisms, and
similarities in early
development.
Evidence of Evolution
 Homologous structures
 Structures that have different mature forms but develop from the
same embryonic tissues
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Evidence of Evolution
 15.3 NOTES #4
 Identify evidence Darwin used to present
his case for evolution.

THE FOSSIL RECORD ALLOWED DARWIN
TO SEE A HISTORY OF LIFE ON EARTH.

GEOGRAPHIC DISTRIBUTION OF SIMILAR
SPECIES THAT SHARE A COMMON
ANCESTOR.

STRUCTURES DEVELOP FROM THE SAME
EMBRYONIC TISSUE, OR HOMOLOGOUS
STRUCTURES.

SIMILAR EMBRYONIC CELLS DEVELOP IN
THE SAME ORDER IN RELATED SPECIES.
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Evidence of Evolution
 15.3 NOTES #5
 State Darwin’s theory of natural selection.
 Individuals differ, hence variation
is heritable.
 More offspring are born than can
survive.
 Competition occurs among
organisms.
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