Ground Rules, exams, etc. (no

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Second Exam Thursday 2 April 2015 Covers
Chapters 5, 8, 9, and 10 Lectures 10 to 19 plus
Agriculture Global Warming The Vanishing Book
of Life on Earth Plastics Intelligent
Design? The Weakest Link Technology Economics
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Population Growth and Regulation S - shaped
sigmoidal population growth Verhulst-Pearl
Logistic Equation dN/dt rN (K
N)/K Assumptions, Derivation Density
Dependence versus Density Independence Equilibriu
m, Opportunistic, and Fugitive species r-selectio
n versus K-selection (r-K selection
Continuum) Correlates of r and K-selection, Bet
Hedging Winemillers 3-dimensional fish life
history surface Population Change versus
Population Density Plots Microtine Rodent
Population Fluctuations Hudson Bay Fur Company
Snowshoe Hare and Lynx Cycles
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http//www.commondreams.org/view/2011/03/07-0
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Notice apparent 10-year periodicity
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Population Cycles

• Sunspot Hypothesis
• Time Lags
• Stress Phenomena Hypothesis
• Predator-Prey Oscillations
• Epidemiology-Parasite Load Hypothesis
• Food Quantity Hypothesis
• Nutrient Recovery
• Other Food Quality Hypotheses
• Genetic Control Hypothesis

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Sunspot Hypothesis (Sinclair et al. 1993. Am.
Nat.) 10 year cycle embedded within 30-50 year
periods Maunder minimum 1645-1715 Three periods
of high sunspot maxima 1751-1787 1838-1870
1948-1993 Canadian Government survey
1931-1948 Hare cycle synchronized across North
America Yukon 5km strip, tree growth rings (N
368 trees) One tree germinated in 1675 (gt300
years old) Hares prefer palatable shrubs, but
will eat spruce leaving dark tree ring marks
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Other Food Quality Hypotheses Microtus
(Freeland 1974) palatability ltgt
toxic
Snowshoe hares Plant chemical defenses
against herbivory (Bryant 1980)
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Chittys Genetic Control Hypothesis
Could optimal reproductive tactics be involved
in driving population cycles?
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Population Cycles

• Sunspot Hypothesis
• Time Lags
• Stress Phenomena Hypothesis
• Predator-Prey Oscillations
• Epidemiology-Parasite Load Hypothesis
• Food Quantity Hypothesis
• Nutrient Recovery
• Other Food Quality Hypotheses
• Genetic Control Hypothesis

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Social Behavior Hermits must have lower
fitness than social individuals Clumped, random,
or dispersed (variance/mean ratio) mobility
motility vagility (sedentary sessile
organisms) Use of Space Philopatry Fluid
versus Viscous Populations Individual
Distance, Daily Movements Home
Range Territoriality (economic
defendability) Resource in short
supply Feeding Territories Nesting
Territories Mating Territories
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V
Net Benefit
V
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Sexual Reproduction Monoecious versus
Diecious Evolution of Sex gt Anisogamy Diploidy
as a fail-safe mechanism Costs of Sexual
Reproduction (halves heritability!) Facultative
Sexuality (Ursula LeGuin -- Left Hand of
Darkness) Protandry ltgt Protogyny (Social
control) Parthenogenesis (unisexual
species) Possible advantages of sexual
reproduction include two parents can raise
twice as many progeny mix genes with desirable
genes (enhances fitness) reduced sibling
competition heterozygosity biparental origin
of many unisexual species
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Robert Warner
No Sex Change Protogyny
Protandry
Male
Female
Male
Female Male
Female
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Why have males? The biological advantage of a
sex ratio that is unbalanced in favor of females
is readily apparent in a species with a
promiscuous mating system. Since one male could
fertilize several females under such a system,
survival of a number of males equal to the
number of females would be wasteful of food,
home sites, and other requirements for existence.
The contribution of some of the surplus males to
feeding the predators on the population would be
economically advantageous. In other words, the
eating of the less valuable (to the population)
males by predators would tend to reduce the
predator pressure on the more valuable females.
Blair (1960) The Rusty Lizard
W. Frank Blair
Sceloporus olivaceus
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Sex Ratio Proportion of Males Primary,
Secondary, Tertiary, Quaternary Why have
males? Fishers theory equal investment in the
two sexes
Ronald A. Fisher
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Comparison of the Contribution to Future
Generations of Various Families in Case a in
Populations with Different Sex Ratios ____________
__________________________________________________
____ Case a Number of Males Number of
Females __________________________________________
________________________ Initial
population 100 100 Family A 4
0 Family C 2 2 Subsequent
population (sum) 106 102 CA 4/106
0.03773 CC 2/106 2/102 0.03846 (family C
has a higher reproductive success) _______________
__________________________________________________
_ Note The contribution of family x is
designated Cx.
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Comparison of the Contribution to Future
Generations of Various Families in Case a in
Populations with Different Sex Ratios ____________
__________________________________________________
____ Case a Number of Males Number of
Females _________________________________________
_________________________ Initial
population 100 100 Family E 0
4 Family C 2 2 Subsequent
population (sum) 102 106 CE 4/106
0.03773 CC 2/106 2/102 0.03846 (family C
has a higher reproductive success) ______________
__________________________________________________
__ Note The contribution of family x is
designated Cx.
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Comparison of the Contribution to Future
Generations of Various Families in Case a in
Populations with Different Sex Ratios ____________
__________________________________________________
____ Case a Number of Males Number of
Females _________________________________________
_________________________ Initial
population 100 100 Family A 4
0 Family C 2 2 Family E
0 4 Subsequent population
(sum) 106 106 CA 4/106 0.03773 CC
2/106 2/106 0.03773 All three families have
equal success CE 4/106 0.03773 _____________
__________________________________________________
___ Note The contribution of family x is
designated Cx.
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__________________________________________________
_________________________ Case b Number of
Males Number of Females _________________________
__________________________________________________
_ Initial population 100 100 Family A
2 0 Family B 1
2 Subsequent population (sum) 103 102 CA
2/103 0.01942 CB 1/103 2/102 0.02932
(family B is more successful) Initial
population 100 100 Family B 1
2 Family C 0 4 Subsequent
population (sum) 101 106 CB 1/101 2/106
0.02877 CC 4/106 0.03773 (family C is more
successful than family B) Natural selection will
favor families with an excess of females until
the population reaches its equilibrium sex ratio
(below). Initial population 100 200 Family
B 1 2 Family C 0
4 Subsequent population (sum) 101 206 C
B 1/101 2/206 0.001971 CC 4/206
0.01942 (family B now has the advantage) _________
__________________________________________________
__________________ Note The contribution of
family x is designated Cx.
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Differential Mortality of the sexes during the
period of parental care.
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Differential Mortality of the sexes during the
period of parental care