EVOLUTION

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EVOLUTION
CHAPTER 15
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• 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

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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
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RESISTANCE TO THE THEORY OF EVOLUTION
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DARWINS 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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DARWINS 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
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DESIRE TO CHANGE
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Use and Disuse
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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

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• 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
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FINCHES
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DARWINS INFLUENCES
MALTHUSOverpopulation and species control
LYELL Earth is subject to slow but continuous
cycles of erosion Proposed uniformitarianism,
rates and processes of change are constant
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• 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.

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DARWINS 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
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ON THE ORIGIN OF SPECIES

• ......ALL THIS LEADS TO HIS THEORY OF NATURAL
  SELECTION and SURVIVAL OF THE FITTEST
• 1859 Publication
• Wallace influence

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WITNESSING NATURAL SELECTION
Early 19th century Industrial Revolution
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Evolution evidence Fossils
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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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2006 Fossil Discovery of Early Tetrapod

• Tiktaalik
• missing link from sea to land animals

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Evolution evidence Homologous Structures

• Similar structure
• Similar development
• Different functions
• Evidence of close evolutionary relationship
• recent common ancestor

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Homologous structures
spines
leaves
succulent leaves
tendrils
needles
colored leaves
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Evolution evidence Analogous Structures

• Separate evolution of structures
• similar functions
• similar external form
• different internal structure development
• different origin
• no evolutionary relationship

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Evolution evidence Comparative Embryology
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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
  non-critical structures without reducing fitness
• snakes whales remains of pelvis leg bones
  of walking ancestors
• eyes on blind cave fish
• human tail bone

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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

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Evolution evidence Biogeography
Fig. 22-20

• Darwins 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

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NATURAL SELECTION IN ACTION

• Insecticide drug resistance
• insecticide didnt kill all individuals
• resistant survivors reproduce
• resistance is inherited
• insecticide becomes less less effective

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ARTIFICIAL SELECTION

• Artificial breeding can use variations in
  populations to create vastly different breeds
  varieties

descendants of wild mustard
descendants of the wolf