Transcript Darwin and evolution

– Varieties of life forms
Figure 1.4C-F
Clown, Fool, or Well Adapted?
• All organisms have evolutionary adaptations
– Inherited characteristics that enhance their
ability to survive and reproduce
• blue-footed booby
• Large, webbed feet help
propel the bird through
water at high speeds
– A streamlined shape, large tail, and nostrils that
close are useful for diving
– Specialized salt-secreting glands manage salt
intake while at sea
Evolution explains the unity and
diversity of life
• Charles Darwin synthesized the Theory of
Evolution by natural selection
– Theory vs hypothesis
• Evolution is the core theme
of biology
Figure 1.6A
• The voyage of the Beagle
Great
Britain
Europe
North
America
Pacific
Ocean
Atlantic
Ocean
Africa
Galápagos
Islands
Equator
South
America
Australia
Cape of
Good Hope
Tasmania
Cape Horn
Tierra del Fuego
New
Zealand
Figure 13.1B
Prevalent ideas at Darwin’s time
• species are fixed
• Earth is about 6,ooo yrs old
New ideas proposed
• Fossils indicated the earth was very
• Lyell, a geologist, argued that land forms
changed constantly.
• Lamarck proposed that organisms changed and
these changes were passed to progeny.
• 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
• Darwin became convinced that the Earth was old
and continually changing
• Mex. marine snail shells on high mtns
– 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
Darwin proposed natural selection as the
mechanism of evolution
• Darwin observed that
– organisms produce more offspring than the
environment can support
– organisms vary in many characteristics
– these variations can be inherited
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• Darwin concluded that individuals best suited
for an environment are more likely to survive
and reproduce than those less well adapted
– As a result, the proportion of individuals with
favorable characteristics increases
– Populations gradually change in response to the
environment
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• natural selection
explains the
mechanism of
evolution
Pesticide-resistant
insects
(1) Population with varied inherited traits
(2) Elimination of individuals with certain traits
Antibiotic-resistant
bacteria
Figure 1.6B
(3) Reproduction of survivors
• Charles Darwin, 1874
Figure 13.1x2
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• Alfred Wallace
Figure 13.1x6
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• Darwin cartoon
Figure 13.1x3
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• Evolution happens when populations of
organisms with inherited variations are
exposed to environmental factors that favor
the reproductive success of some individuals
over others
– Natural selection is the editing mechanism
– Evolution is based on adaptations
Figure 1.6C
Fossils provide strong evidence for
evolution
– Hominid skull
– Petrified trees
Figure 13.2A, B
– Ammonite casts
– Fossilized organic
matter in a leaf
Figure 13.2C, D
– Scorpion in amber
– “Ice Man”
– acid bogs
Figure 13.2E, F
• Mammoth tusks
Figure 13.2x4
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• fossils show that organisms
have appeared in a historical
sequence
• Many fossils link
early extinct
species with
species living today
– hind leg bones of
fossil whales
Figure 13.2G, H
Other evidence for evolution
– Biogeography
– Comparative
anatomy
– Comparative
embryology
Human
Cat
Whale
Bat
Figure 13.3A
– Molecular biology - protein “clocks”
Human
Rhesus monkey
Last common
ancestor lived
26 million years
ago (MYA),
based on
fossil evidence
Mouse
Chicken
Frog
Lamprey
80 MYA
275 MYA
330 MYA
450 MYA
Figure 13.3B
No
predestined
goal of
evolution
Figure 15.8