Humans have become the single most potent agents of

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Humans have become the single most potent agents
of evolutionary change on this planet. They
have caused an evolution explosion. The
following are some of the ways this is
happening 1. Evolution of insecticide
resistance in plant-eating insects. 2.
Evolution of antibiotic resistance in
disease-causing bacteria (e.g.TB). 3.
Evolution of changes in the growth
characteristics, reproductive maturation
schedules and environmental requirements
of commercially exploited organisms, often
through over-harvesting. 4. Introduction of
engineered herbicide resistance genes into
the weeds that were their target species.
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New control agent (effective at first)
Rare resistant mutation
Only resistant organism survives
New resistant population
GENERAL MODEL FOR THE EVOLUTION OF INSECTICIDE OR
ANTIBIOTIC RESISTANCE
CONTROL AGENT NOW INEFFECTIVE
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Population now mostly small fish with different
life-history characteristics
Original population both large and small adult
fish. Differences have a genetic basis.
Large fish selectively removed by large scale
commercial fishing
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CROP PLANT
WEED
Apply herbicide in massive amts
ENGINEERED GENE FOR HERBICIDE RESISTANCE
Weeds die, crop plants unaffected
Resistance gene now in weed gene pool
Resistance gene in hybrid and gene flow
between hybrid and weed species
Hybridization between crop plant and weed
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Resistance gene transferred to other related
species
Eventual transfer to many other species
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The Great Chain (or scale) of Being
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Jean Baptiste Antoine de Monet, chavalier de
Lamarck
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Catastrophism
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Charles Lyell, a geologist, championed
uniformitarianism --- the notion that, over
time, events with very small immediate effects
can result in profound changes.
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By the beginning of the 19th century, scientists,
many of whom were also clergy, were almost
routinely making observations for which they had
no readily apparent explanation. The most
important of these were 1. Great age of the
earth 2. Extinct forms 3. Homology 4.
Vestigial structures 5. Transitional forms
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Many extinct organisms were discovered as
fossils. These discoveries were profoundly
disturbing in ways we cant easily appreciate,
for most scholars accepted the literal truth of
the biblical account of creation as a scientific
explanation.
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What can be more curious than that the hand of
man formed for grasping, that of a mole for
digging, the leg of a horse, the paddle of a
porpoise, and the wing of a bat, should all
be constructed on the same pattern and should
include similar bones and in the same relative
positions?
HOMOLOGY
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Homology extends to many anatomical structures
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Homology also extends to embryos
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Are any of the adaptations for rapid movement in
water in these three groups of vertebrates
really homologous?
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• Test your understanding of homology
• Which of the following pairs of structures are
  homologous and
• which are analogous?
• Dorsal fins of porpoise and salmon.
• The jointed leg of a ladybird beetle and a robin.
• A siamang apes tail and a human coccyx.
• The bright red bracts (modified leaves) of a
  poinsetta
• and the green leaves of a rose?
• e. The bright red bracts of a poinsetta and
  the red petals of a rose

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• Some questions to think about from the text
• What are processed pseudogenes? Why are
  shared processed pseudogenes considered evidence
  of common ancestry?
• Why are shared genetic flaws considered
  evidence of common ancestry? What do they tell
  us about our ancestry?
• Be familiar with the definitions and significance
  of the following terms
• a. retroposon
• b. exon
• c. intron
• d. geologic time scale
• e. radiometric dating