Evolution

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Chapter 15

• Evolution

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Clown, Fool, or Simply Well Adapted?

• All organisms have evolutionary adaptations
• Inherited characteristics that enhance their
  ability to survive and reproduce
• Example The blue-footed booby of the Galápagos
  Islands has features that help it succeed in its
  environment
• Large, webbed feet help propel the bird
  throughwater at high speeds

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• A streamlined shape, large tail, and nostrils
  that close are useful for diving

• Specialized salt-secreting glands manage salt
  intake while at sea

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A sea voyage helped Darwin frame his theory of
evolution
EVIDENCE OF EVOLUTION

• Pre-Darwin - Aristotle and the Judeo-Christian
  culture believed that species are fixed
• Fossils suggested that life forms change

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• Lamarcks Ideas on Evolution

• French biologist Jean Baptiste Lamarck
  (1744-1829) thought simple organisms could arise
  from non-living matter.
• He also proposed that individuals could acquire
  traits during their lifetimes as a result of
  experience or behavior, then could pass on these
  traits to offspring.

Figure 13.1A
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• The voyage of the Beagle (1830s)

Great Britain
Europe
NorthAmerica
PacificOcean
AtlanticOcean
Africa
GalápagosIslands
Equator
SouthAmerica
Australia
Andes
Cape ofGood Hope
Tasmania
Cape Horn
NewZealand
Tierra del Fuego
Figure 13.1B
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• Darwin became convinced that the Earth was old
  and continually changing

• While on his voyage, Darwin concluded
• living things also change, or evolve over
  generations
• 2. living species descended from earlier
  life-forms descent with modification

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The study of fossils provides strong evidence for
evolution

• Fossils and the fossil record strongly support
  the theory of evolution
• Hominid skull

• Petrified trees

Figure 13.2A, B
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• Ammonite casts

• Fossilized organic matter in a leaf

Figure 13.2C, D
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• Scorpion in amber

• Ice Man

Figure 13.2E, F
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• 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 land-dwelling ancestors

Figure 13.2G, H
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Similarities between organisms

• Homologous Structures
• Striking similarities among the bones of very
  different types of arms and legs.
• Vestigial Organs seem to have little or no
  obvious function (appendix)

Human
Cat
Whale
Bat
Figure 13.3A
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Darwin proposed natural selection as the
mechanism of evolution
DARWINS THEORY

• Darwin observed that
• organisms produce more offspring than the
  environment can support
• organisms vary in many characteristics
• individuals must compete with each other in a
  struggle for existence
• differential reproduction ensures that organisms
  with the best adaptations will survive and
  reproduce.

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• Darwin concluded that individuals best adapted to
  a particular environment are more likely to
  survive and reproduce than those less well adapted

• Darwin saw natural selection as the basic
  mechanism of evolution
• As a result, the proportion of individuals with
  favorable characteristics increases
• Populations gradually change in response to the
  environment

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• Darwin also saw that when humans choose organisms
  with specific characteristics as breeding stock,
  they are performing the role of the environment

• This is called artificial selection
• Example of artificial selection in plants five
  vegetables derived from wild mustard

Figure 13.4A
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• Example of artificial selection in animals dog
  breeding

English springerspaniel
German shepherd
Yorkshire terrier
Mini-dachshund
Golden retriever
Hundreds tothousands of yearsof
breeding(artificial selection)
Ancestral dog
Figure 13.4B
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• These five canine species evolved from a common
  ancestor through natural selection

African wilddog
Coyote
Fox
Wolf
Jackal
Thousands tomillions of yearsof natural
selection
Ancestral canine
Figure 13.4C
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Connection Scientists can observe natural
selection in action

• Evolutionary adaptations have been observed in
  populations of birds, insects, and many other
  organisms
• Example camouflage adaptations of mantids that
  live in different environments

Figure 13.5A
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• The evolution of insecticide resistance is an
  example of natural selection in action

Insecticideapplication
Chromosome with geneconferring resistanceto
insecticide
Additionalapplications of thesame insecticide
willbe less effective, andthe frequency
ofresistant insects inthe populationwill grow
Survivor
Figure 13.5B
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Figure 15.1
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Terms to know

• Evolution
• Fossil record
• Adaptation
• Fitness
• Homologous structures
• Vestigial organs
• Artificial selection
• Natural selection
• Common decent