Download The Origin of Species

 Biology came of age on November 24, 1859. Charles
Darwin published On the Origin of Species by Means of
Natural Selection, an assemblage of facts about the
natural world.
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Common beliefs
 Who created living organisms?
 Did they evolve?
 What was the age of the earth?
 Did the earth change?
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1778 – Buffon
1790 - Cuvier
1809 – Lamarck
1830 – Lyell
1831-1836 – Darwin travels on the HMS Beagle
1844 – Darwin writes his essay
1858 – Wallace sends his theory to Darwin
1859 – The Origin of Species is published
HMS Beagle
Darwin
in 1840
North
America
Great
Britain
Europe
Asia
ATLANTIC
OCEAN
Africa
Galápagos
Pinta
Islands
PACIFIC
OCEAN
Marchena
South
America
Genovesa
Equator
Santiago
Daphne Islands
Pinzón
Fernandina
Isabela
0
0
Equator
40 km
Santa
Cruz
Santa
Fe
Florenza
San
Cristobal
Australia
PACIFIC
OCEAN
Cape of
Good Hope
Cape Horn
Española
40 miles
Tierra del Fuego
Tasmania
New Zealand
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(a) Charles Darwin and (b) Alfred Wallace wrote scientific papers on natural selection that
were presented together before the Linnean Society in 1858.
CHARLES DARWIN’S UNEXPECTED
PATTERNS
1.
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Large
ground
finch
Divergence from
original population
Same species w/
different traits?
13 different sp.

Warbler finch
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Woodpecker finch
CHARLES DARWIN’S UNEXPECTED
PATTERNS CON’T.
Glyptodont
2.
Fossil Evidence

Similarity between fossils
of extinct & extant species
occurred at every location
Hairy Armadillo
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1. Descent with Modification  Organisms
inhabiting Earth today descended from ancestral
species.
- As organisms spread over various habitats,
they are modified or changed by
accumulating adaptations to diverse ways of
life
- AKA evolution: a change in the genetic
composition of a population over time.
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Darwin’s Two Main Points in The Origin of Species con’t.
2. Natural Selection is the mechanism for descent
with modification
▪ Process in which organisms with certain inherited
characteristics are more likely to survive and reproduce
than are individuals with other characteristics.
 Populations change over generations.
 Natural selection thus leads to evolution.
 Darwinian Fitness: measure of viable offspring
compared to other members of that species
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 Evolution leaves observable signs.
 We will examine five of the many lines of evidence in
support of evolution:
1.
2.
3.
4.
5.
the fossil record,
biogeography,
comparative anatomy,
comparative embryology, and
molecular biology.
© 2013 Pearson Education, Inc.
Australia
Common
ringtail
possum
Koala
Common wombat
Red kangaroo
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The similar construction of these appendages indicates that these organisms share a
common ancestor.
Pharyngeal
pouches
Post-anal
tail
Chicken embryo
Human embryo
Primate
Percent of selected DNA
sequences that match a
chimpanzee’s DNA
92%
Chimpanzee
Human
Gorilla
Orangutan
Gibbon
Old World
monkey
96%
100%
1. All species tend to produce excessive numbers of offspring
2. Organisms vary, and much of this variation is heritable.
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 Examples of natural selection include
▪ pesticide-resistant insects,
▪ antibiotic-resistant bacteria, and
▪ drug-resistant strains of HIV.
© 2013 Pearson Education, Inc.
Frequency of
individuals
Evolved
Original
population population
(a) Directional selection
Original
population
Phenotypes (fur color))
(b) Disruptive selection
(c) Stabilizing selection
Three General Outcomes of Natural Selection
Directional selection shifts the overall makeup
of a population by selecting in favor of one
extreme phenotype.
2. Disruptive/Diversifying selection can lead to a
balance between two or more contrasting phenotypic
forms in a population.
3. Stabilizing selection favors intermediate
phenotypes, occurs in relatively stable
environments, and is the most common.
1.
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As the Industrial Revolution caused trees to darken from soot, darker colored peppered
moths were better camouflaged than the lighter colored ones, which caused there to be
more of the darker colored moths in the population.
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Organisms can change over time.
Some organisms have gone extinct.
Earth is ~ 4.5 billion years old
The geology of the earth is not constant, but
always changing.
Organisms descend from ancestral species.