Download Natural Selection

EVOLUTION
CHAPTER 15
• Evolution: the change over
time of the genetic
composition of populations
• Natural Selection:
populations of organisms can
change over the generations if
individuals having certain
heritable traits leave more
offspring than others
(differential reproductive
success)
• Evolutionary Adapations: a
prevalence of inherited
characteristics that enhance
organisms’ survival and
reproduction
EVOLUTIONARY HISTORY
– Linnaeus - taxonomy
- Lyell - uniformitarianism
– Hutton - gradualism
- Darwin - evolution
– Lamarck - evolution
- Mendel - inheritance
– Malthus - populations
- Wallace - evolution
– Cuvier - paleontology
- Count Buffon - evolution
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RESISTANCE TO THE THEORY OF EVOLUTION
RESISTANCE TO THE THEORY OF EVOLUTION
DARWIN’S INFLUENCES

Taxonomy matured during mid-eighteenth
century

Linnaeus believed in:

He developed the binomial system of nomenclature


System of classification for living things
Count Buffon:
Wrote 44-volume catalog of all known plants and
animals
 Suggested descent with modification

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DARWIN’S INFLUENCES

Lamarck = First biologist to:



Propose evolution
Link diversity with environmental adaptation
Concluded more complex organisms are descended
from less complex organisms: SIMPLE TO
COMPLEX

Proposed inheritance of acquired characteristics –
Lamarckianism
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Passing on Acquired Traits
DESIRE TO CHANGE
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Use and Disuse
HMS BEAGLE VOYAGE
• Invited to travel around the
world
– 1831-1836 (22 years old!)
– makes many observations of
nature
• main mission of the Beagle was to chart
South American coastline
• While on the voyage of the HMS Beagle in
the 1830s, Charles Darwin observed
– similarities between living and fossil organisms
– the diversity of life on the Galápagos Islands,
such as blue-footed boobies and giant tortoises
Figure 13.1A
FINCHES
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DARWIN’S INFLUENCES
MALTHUS
Overpopulation and
species control
LYELL
Earth is subject to slow but
continuous cycles of erosion
Proposed uniformitarianism,
rates and processes of change
are constant
• Darwin became convinced that the Earth
was old and continually changing
– He concluded that living things also change, or
evolve over generations
– He also stated that living species descended from
earlier life-forms: descent with modification
(originally Buffon and Erasmus Darwin)
• All organisms are related through decent from an ancestor that lived in the
remote past.
DARWIN’S 5 MAJOR CONCLUSIONS
1. Population has Variation
2. Variations may be favorable
3. More offspring are produced
than survive
4. Survivors have favorable traits
5. Populations change over time
ON THE ORIGIN
OF SPECIES
•
•
•
......ALL THIS LEADS TO HIS
THEORY OF NATURAL
SELECTION and SURVIVAL OF
THE FITTEST
1859 Publication
Wallace influence
WITNESSING NATURAL
SELECTION
Early 19th
century
Industrial
Revolution
Evolution evidence:
Fossils
• The fossil record shows that
organisms have appeared in
a historical sequence
• Many fossils link
early extinct species
with species living
today
– These fossilized hind
leg bones link living
whales with their landdwelling ancestors
Figure 13.2G, H
2006 Fossil Discovery of Early
Tetrapod
• Tiktaalik
– “missing link” from sea to land animals
•
Evolution evidence:
Homologous
Structures
Similar
structure
• Similar
development
• Different
functions
• Evidence of
close
evolutionary
relationship
– recent
common
ancestor
Homologous
structures
spines
leaves
succulent leaves
needles
colored leaves
tendrils
Evolution evidence:
Analogous Structures
 Separate evolution of
structures





similar functions
similar external form
different internal
structure &
development
different origin
no evolutionary
relationship
Don’t be fooled
by their looks!
Evolution evidence:
Comparative
Embryology
Evolution evidence:
Vestigial Structures
• Modern animals may have structures that serve
little or no function
– remnants of structures that were functional in
ancestral species
– deleterious mutations accumulate in genes for noncritical structures without reducing fitness
• snakes & whales — remains of pelvis & leg bones of
walking ancestors
• eyes on blind cave fish
• human tail bone
Evolution evidence:
Molecular Biology
• Similarities in DNA,
proteins, genes, and
gene products
• Common genetic code
Closely related species have
sequences that are more similar
than distantly related species
DNA & proteins are a molecular
record of evolutionary
relationships
Fig. 22-20
Evolution evidence:
Biogeography
• Darwin’s observations
of biogeography, the
geographic distribution
of species, formed an
important part of his
theory of evolution
• Islands have many
endemic species that
are often closely related
to species on the
mainland
NATURAL SELECTION IN ACTION
•
Insecticide &
drug resistance
–insecticide didn’t
kill all individuals
–resistant survivors
reproduce
–resistance is inherited
–insecticide becomes less &
less effective
ARTIFICIAL SELECTION
•
Artificial breeding can use variations in
populations to create vastly different
“breeds” & “varieties”
“descendants” of wild mustard
“descendants” of the wolf