DARWIN

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DARWIN

• Review for Lecture 211

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Announcements

• LAB 7 more VIRTUAL FLIES.
• Typed Report due next Monday.
• Like last virtual fly lab, except choose from two
  harder mutations
• Attendance during lab optional. Use lab or
  dungeon computers any time.
• But no help available except during lab. Dont
  even ask unless you came to lab.

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most important concept

•      
• Darwin's concept of Natural Selection is a theory
  to explain evolution.
• DNA -gtmore DNA --gt RNA -gt protein is still
  important in understanding the relationship
  between Natural Selection and inheritance.

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Darwin's four postulates

• Individuals have variations
• Variations are genetic
• only some offspring survive and reproduce
• Natural Selection survival and reproduction of
  the fittest

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Freeman believes that
Darwin's theory was more revolutionary than
Watson and Crick's "Central Dogma"

• Today the whole idea that animals and plants
  evolve adaptations for particular habitats is a
  basic assumption (the cornerstone) of ecology,
  physiology, genetics, anatomy, embryology,
  biochemistry, medicine, agriculture ....

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Why is evolution so controversial?

• Because the Homo sapiens brain has evolved to
  search for patterns and a supernatural
  explanation is easy to understand.
• And because ...
• And also because...

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evolution is controversial but NOT for SCIENTISTS

• When you know more about the natural world, its
  easier to understand natural explanations.
  Supernatural explanations are not necessary for
  most scientists.
• Science is limited to what we can observe and
  disprove. Supernatural events cannot be observed
  with scientific tools.
• Evolution is the only scientific explanation of
  the biological history of the earth. Nobody so
  far has proposed any other disprovable
  explanation which is consistent with the
  evidence. The last valid scientific objections
  were resolved during the 19th century. Nobody
  has even found scientific evidence against
  evolution.
• And we all remember that science deals only with
  hypotheses which can be disproved by experiments.

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Box 21.1 Figure 1 a,b
Charles Darwin
Alfred Russel Wallace
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most important concept

•      
• Darwin's concept of Natural Selection is a theory
  to explain evolution.
• DNA -gtmore DNA --gt RNA -gt protein is still
  important in understanding the relationship
  between Natural Selection and inheritance.

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Darwin's four postulates

• Individuals have variations
• Variations are genetic
• only some offspring survive and reproduce
• Natural Selection survival and reproduction of
  the fittest

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Measuring Darwinian Fitness

• Higher birth rate (fecundity)
• lower mortality rate, especially lower juvenile
  mortality rate
• documenting genetic adaptations which contribute
  to higher fecundity or lower mortality in a
  particular environment.

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Chapter 21
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DARWINs most famous cases

• Voyage of the Beagle to the Galapagos
• The Finches of the Galapagos

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Figure 21.1a,b
The Galapagos mockingbirds differ only slightly
in size, shape, and coloration.
Nesomimus melanotis
Nesomimus macdonaldi
Nesomimus parvulus
Nesomimus trifasciatus
Darwin reasoned that they are similar because
they share a common ancestor.
N. melanotis
N. macdonaldi
N. trifasciatus
N. parvulus
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Phylogenies

• Evolutionary trees phylogenies

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Homology similarities shared by species with a
common ancestor
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Box 21.2 Figure 1a
Analogy When similarities result from convergent
evolution
1m
1m
Ichthyosaur
Common dolphin
Whales and dolphins
Monotremes
Ichthyosaurs
Pterosaurs
Elephants
Marsupials
Dinosaurs
Synapsids
Primates
Lizards
Rodents
Birds
The members of lineages between the dolphins
and ichthyosaurs do not have adaptions like -
streamlined bodies - long jaws filled with
teeth - fins and flippers
The dolphin and ichthyosaur lineages are far
apart on the evolutionary tree, suggesting that
they are not closely related
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Figure 21.2a
Structural homology
Humerus
Radius and ulna
Carpals
Metacarpals
Phalanges
Turtle
Human
Horse
Bird
Bat
Seal
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Homology v. Analogy

• Homology similarities shared by species with a
  common ancestor
• Analogy similarities without a close ancestor.
  EXAMPLES for structures?
• (Phylogeny family tree)

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Figure 21.2c
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Figure 21.2b
Developmental homology
Both the chick and the human have gill pouches
and tails
Gill pouch
Tail
Chick
Human
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OLD SLOGAN

•      
• Ontogeny recapitulates phylogeny

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Figure 21.4, left
Human coccyx
Capuchin monkey tail (used for balance,
locomotion)
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Figure 21.4, right
Erect hair on chimp (insulation, emotional
display)
Human goosebumps
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Experimental Evidence of Evolution byNatural
Selection

• Case Study of Rise in Resistance to Antibiotics
  inTuberculosis Bacteria (Fig. 21.5, 21.6)
• Case Study of Natural Selection by Pollinators of
  Alpine Skypilot Plants (Fig. 21.7a,b, 21.8, 21.9,
  21.10, 21.11)

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Did Mycobacterium tuberculosis become resistant
to rifampin by natural selection?

•      
• how to answer
• compare with Darwins postulates

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Darwin's four postulates

• Individuals have variations
• Variations are genetic
• only some offspring survive and reproduce
• Natural Selection survival and reproduction of
  the fittest

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Darwin's concept

• Natural Selection survival and reproduction of
  the fittest.
• Did some bacteria inherit adaptations which
  helped them survive and reproduce better than
  others?

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natural selection EXPERIMENTS

• resistance in MANY germs and agricultural pests
• Most famous case peppered moth
• documented adaptation to environmental changes
  during the 20th century
• parsnip worms
• copper tolerance in grasses near mines
• nitrate tolerance in lake algae
• etc.

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natural selection EXPERIMENTS

• Other experiments over centuries
• fossils
• mummies
• ice men and other frozen specimens
• cave coprology etc.
• museum pelts

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Figure 21.7 a,b
In tundra habitats above timberline, the alpine
skypilot is pollinated primarily by bumblebees.
28 24 20 16 12 8 4 0
Number of individuals
10 12 14 16 18 20 22
Tundra flower big and sweet-smelling
Flower size (mm)
In forested habitats below timberline, the alpine
skypilot is pollinated primarily by flies.
10
8
6
Number of individuals
4
2
0
10 12 14 16 18 20 22
Below-timberline flower small and
skunky-smelling
Flower size (mm)
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Figure 21.7a
In tundra habitats above timberline, the alpine
skypilot ispollinated primarily by bumblebees.
28 24 20 16 12 8 4 0
Number of individuals
10 12 14 16 18 20 22
Tundra flower big and sweet-smelling
Tundra pollinator bumblebee
Flower size (mm)
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Figure 21.7b
In forested habitats below timberline, the alpine
skypilot ispollinated primarily by flies.
10
8
6
Number of individuals
4
2
0
10 12 14 16 18 20 22
Below-timberline pollinator fly
Below-timberline flower small and skunky-smelling
Flower size (mm)
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Figure 21.8
110
100
80
60
Bee visits received
40
20
0
3
2
1
0
1
2
4
Size score
Large flowers
Small flowers
Short stems
Tall stems
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Figure 21.9
1.0
0.8
0.6
Relative fitness (fecundity)
0.4
0.2
0
40
0
20
60
80
100
110
Bee visits received
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Figure 21.10
18
16
14
Offsprings flower size (mm)
12
10
8
8
10
12
14
16
18
Mothers flower size (mm)
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Figure 21.11
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Applying Darwin's ideas

• Did some skyrockets inherit adaptations which
  helped them survive and reproduce better than
  others in a specific habitat?

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EVIDENCE WE CAN OBSERVE

• Extinctions
• fossils
• structural homologies
• developmental homologies
• genetic homologies
• vestigial traits
• changes in adaptations
• repeated patterns in all of the above

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most important concept

•      
• Darwins theory NATURAL SELECTION

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most important concept

•      
• DNA -gtmore DNA --gt RNA -gt adaptation
• This "central dogma" of today's molecular biology
  has applications
• in natural selection.

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MORE ABOUT

• Darwin http//campus.queens.edu/faculty/jannr/darw
  in.htm
• Creationism
• http//campus.queens.edu/faculty/jannr/creationism
  .htm
• Evolution
• http//campus.queens.edu/faculty/jannr/evolution.h
  tm

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