A zoo can only afford to keep a breeding population of 10 African elephants'

1

• A zoo can only afford to keep a breeding
  population of 10 African elephants.
• If the breeding population is held at this
  size, how many generations would it take for
• it to lose 25 of its initial heterozygosity?
• a. roughly 6
• b. roughly 4
• c. exactly 7
• d. 10
• e. insufficient data to answer this question

2

• A zoo can only afford to keep a breeding
  population of 10 African elephants.
• If the breeding population is held at this
  size, how many generations would it take for
• it to lose 25 of its initial heterozygosity?
• a. roughly 6
• b. roughly 4
• c. exactly 7
• d. 10
• e. insufficient data to answer this question

Ht H0(1-1/2N)t therefore 0.75 Ht/ H0
(1-1/2N)t so
(.95)t 0.75 t approx. 6
3

• Refer to the previous problem. Two
  generations are kept at a size of 10, but,
• in the third, the governor cuts the budget
  and only 4 animals can be kept and bred.
• What has been the effective population
  size over these three generations?
• a. about 8
• b. about 7
• c. about 4
• d. about 6
• e. none of the above

4

• Refer to the previous problem. Two
  generations are kept at a size of 10, but,
• in the third, the governor cuts the budget
  and only 4 animals can be kept and bred.
• What has been the effective population
  size over these three generations?
• a. about 8
• b. about 7 1/Ne
  1/t(1/N1 1/N2 1/N3)
• c. about 4
  1/3(1/10 1/10 1/4) 1/3(.45) .15,
• Ne 6.6 or about 7
• d. about 6
• e. none of the above

5

• Of the following processes, which is most likely
  responsible
• for the loss of heterozygosity in the zoos
  elephant population
• Mutations
• Migration
• Natural selection
• Genetic drift
• A diet of peanuts

6

• Which of the following statements is true of
  inbreeding?
• it changes gametic but not zygotic frequencies
• b. it changes zygotic but not gametic
  frequencies
• c. it changes gene frequencies but not genotype
  frequencies
• d. it has no effects at all on natural
  populations.

7

• Which of the following statements is true of
  inbreeding?
• it changes gametic but not zygotic frequencies
• b. it changes zygotic but not gametic
  frequencies
• c. it changes gene frequencies but not genotype
  frequencies
• d. it has no effects at all on natural
  populations.

8
_________ __________
__________
__________ 64
18 18 The diagram
above is a summary of an allozyme survey in a
local population of ants. 100 ants were scored.
The enzyme was "pgm" (phosphglucomutase). The
origin of electrophoresis was t oward the bottom
of the paper, but is not shown the postitive
pole is at the top. The numbers under each
pattern are the number of ants who had this
particular pattern (e.g., 64 ants had the
"fast" band only). Which of the following
statements holds? a. The frequency of the allele
encoding the "slow" allozyme is .27 b. The
frequency of the alleles encoding the "fast"
allozyme is .27 c. The population is at HW
equilibrium d. the population is NOT at HW
equilibrium e. a and c are correct f. a and d
are correct g. b and c are correct h. b and d
are correct
9
_________ __________
__________
__________ 64
18 18 The diagram
above is a summary of an allozyme survey in a
local population of ants. 100 ants were scored.
The enzyme was "pgm" (phosphglucomutase). The
origin of electrophoresis was t oward the bottom
of the paper, but is not shown the postitive
pole is at the top. The numbers under each
pattern are the number of ants who had this
particular pattern (e.g., 64 ants had the
"fast" band only). Which of the following
statements holds? a. The frequency of the allele
encoding the "slow" allozyme is .27 b. The
frequency of the alleles encoding the "fast"
allozyme is .27 c. The population is at HW
equilibrium d. the population is NOT at HW
equilibrium e. a and c are correct f. a and d
are correct g. b and c are correct h. b and d
are correct
10

• Organisms such as the naked mole rat discussed in
  class
• might suggest that
• inbreeding depression may not be a universal
  constraint
• on the evolution of mating systems.
• inbreeding depression might be overcome if there
  are
• compensatory advantages to inbreeding in a
  particular
• social system.
• c. inbreeding is universally deleterious
• d. both "a" and "b" might be correct.
• e. both "b" and "c" might be correct.

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Lets digest all this food for thought with a 3
min break!
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Note There is an equilibrium point at which the
phenotypes have equal fitnesses.
13
Self-sterility alleles in monoecious plants
good examples of frequency- dependent selection
pollen female tissue
fertilization? Ax AaAb
yes Ax
Aa Ax
no
A rare allele has high fitness, for it will
almost never be present in both the pollen and
the female tissue. As the allele becomes more
common, pollen and female tissue have an
increasingly greater likelihood of containing
the same allele. So the relative fitness of that
particular allele drops.
14
Frequency-dependent selection also probably plays
an important role in the dynamic between host
and parasite 1. A hypothetical parasite
attacks a host by recognizing and binding
to a specific host protein on cell surfaces.
This protein is variable within the host
population, but at least some of the
parasites can bind to any of the forms. 2. A
mutation occurs in the host, leading to a new
form of cell surface protein. The parasite
cannot recognize the new protein, so the
new allele is favored by selection. It
increases in frequency.
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3. But the parasite has mutations too.
Eventually, the allele for the new host
protein becomes so common that it acts as a
selection pressure on the parasite, and any
new mutations in the parasite genome which can
recognize/bind to the new protein are favored.
Accordingly, the new parasite alleles
increase in frequency, and the host allele
for the new protein loses its selective
advantage--- it now declines in frequency. 4.
A mutation occurs in the host species, leading to
a new form of cell surface protein.
The parasite cannot recognize the new
protein, so the mutation is favored by
selection. It increases in frequency... What
would you guess might be the name of this kind
of dynamic relationship? (Hint Consider the
cold war...)
16
These butterflies are members of two different
species despite their close resemblance to one
another.
Striking resemblances between species, like that
shown here, are obviously not coincidences. What
do they mean, and what can it tell us about
evolutionary processes?
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18
Batesian mimicry Model distasteful,
poisonous, dangerous,
etc.
Mimic not distasteful, poisonous, etc. In
essence, the mimic parasitizes the models
signal
Mullerian mimicry Two or more distasteful,
poisonous, etc. species have a common
warning
coloration. There are no mimics. In essence,
two or more species share a warning signal
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Batesian mimicry in butterflies
models mimics (females)
Nonmimic forms male female
___________________
______________
Male (not a mimic)
Models Mimics
20
Batesian mimicry is not confined to butterflies.
What are these creatures, and which one is model
and which mimic? Note color patterns which
signal danger, I am poisonous or I taste
terribleare sometimes called aposematic or
warning coloration
21
Why is Batesian mimicry considered an
example of frequency-dependent selection?
Ans What happens if the mimic becomes so common
that naïve predators are more likely to
encounter mimics and less likely to encounter
models?
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Mullerian Mimicry
VICEROY
MONARCH
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Mimicry rings --- combinations of Batesian and
Mullerian mimics--- are common among Heliconius
butterflies in the Neotropics
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Mimicry is not confined to buttlerflies. Here is
a splendid example in frogs of the genus
Dendrobites.
These three frogs (a - c) are members of one
species, Dendrobites imitator
D. Variabilis D.
fantasticus D. ventrimaculatus
Each color morph of D. imitator is a Mullerian
mimic of another Dendrobites species that lives
with it in different parts of its range.

25
Why is Mullerian mimicry considered possibly an
example of frequency-dependent selection?
Ans. This kind of mimicry should work best if
the mimetic pattern(s) are at high frequency in
each of the participating species. If they are
rare, naïve predators may never encounter them.
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Camoulflage or disguise mimicry
27
Eyespots are a distinctive form of disguise
mimicry, often easily recognized.
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Cleaner wrasses pick ecto- parasites off many
fishes. There are many species, but most have
a distinctive color pattern.
Aggressive camouflage mimicry!
This fish isnt a wrasse at all. It is a
saber-toothed blenny. It mimics the color
patterns and some of the behaviors of a
cleaner, but then takes bites of flesh from the
host fish.
31
What role might frequency-dependent selection
play in systems of comouflage or disguise
mimicry?
Partial answer Think what might happen if a
common model became rare, or a habitat in which
a disguise worked began to change