Evolution of Reproductive Tactics: semelparous versus iteroparous Reproductive effort (parental investment) Mola mola, white leghorn chicken lines Optimal reproductive tactics Graphical models of tradeoffs between present vs.future progeny Expenditure

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Evolution of Reproductive Tactics semelparous
versus iteroparousReproductive effort (parental
investment)Mola mola, white leghorn chicken
linesOptimal reproductive tacticsGraphical
models of tradeoffs between present vs.future
progenyExpenditure per progeny and optimal
clutch sizeAltrical vs. precocial, nidicolous
vs. nidifugousDeterminant vs. Indeterminant
layers (Flicker example)Avian clutch size --
Lacks parental care hypothesisSeabirds
Albatross egg addition experimentLatitudinal
gradients in avian clutch size
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Age of first reproduction, alpha, ?
menarche Age of last reproduction, omega, ?
Reproductive value vx , Expectation of future
offspring Stable vs. changing populations
Present value of all expected future progeny
Residual reproductive value Intrinsic rate of
increase (little r, per capita b - d)
J-shaped exponential runaway population growth
Differential equation dN/dt rN (b - d)N,
Nt N0 ert Demographic and Environmental
Stochasticity
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Evolution of Reproductive Tactics
Semelparous versus Interoparous Big Bang
versus Repeated Reproduction Reproductive
Effort (parental investment) Age of First
Reproduction, alpha, a Age of Last
Reproduction, omega, ?
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Iteroparous organism
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Semelparous organism
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Patterns in Avian Clutch Sizes Altrical
versus Precocial Nidicolous vs. Nidifugous
Determinant versus Indeterminant
LayersClassic Experiment (1887) Flickers
usually lay 7-8 eggs, but in an egg removal
experiment, a female laid 61 eggs in 63 days
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Great Tit Parus major
David Lack
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European Starling, Sturnus vulgaris
David Lack
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Chimney Swift, Apus apus
David Lack
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Seabirds (Ashmole) Boobies, Gannets, Gulls,
Petrels, Skuas, Terns, Albatrosses Delayed
sexual maturity, Small clutch size, Parental care
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Albatross Egg Addition Experiment
An extra chick added to each of 18 nests a few
days after hatching. These nests with two chicks
were compared to 18 other natural control nests
with only one chick. Three months later, only 5
of the 36 experimental chicks survived from the
nests with 2 chicks, whereas 12 of the 18 chicks
from single chick nests were still alive. Parents
could not find food enough to feed two chicks and
most starved to death.
Diomedea immutabilis
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Latitudinal Gradients in Avian Clutch Size
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Latitudinal Gradients in Avian Clutch Size
Daylength Hypothesis Prey Diversity
Hypothesis Spring Bloom or Competition Hypothesis
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Latitudinal Gradients in Avian Clutch Size

• Daylength Hypothesis
• Prey Diversity Hypothesis (search images)
• Spring Bloom or Competition Hypothesis
• Nest Predation Hypothesis (Skutch)
• Hazards of Migration Hypothesis

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Latitudinal Gradients in Avian Clutch Size
Nest Predation Hypothesis Alexander Skutch
gt
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Latitudinal Gradients in Avian Clutch Size
Hazards of Migration Hypothesis
Falco eleonora
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Evolution of Death Rates Senescence, old age,
genetic dustbin Medawars Test Tube Model
p(surviving one month) 0.9
p(surviving two months) 0.92 p(surviving
x months) 0.9xrecession of time of
expression of the overt effects of a detrimental
alleleprecession of time of expression of the
positive effects of a beneficial allele
Peter Medawar
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Age Distribution of Medawars test tubes
Peter Medawar
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Percentages of people with lactose intolerance
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What starts off slow, finishes in a flash . . .
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What starts off slow, finishes in a flash . . .
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S - shaped sigmoidal population growth
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Verhulst-Pearl Logistic Equation dN/dt rN
rN (N/K) rN (rN2)/K dN/dt rN 1
(N/K) rN (K N)/K dN/dt 0 when (K
N)/K 0 (K N)/K 0 when N K dN/dt
rN (r/K)N2
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Inhibitory effect of each individual On its own
population growth is 1/K
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At equilibrium, birth rate must equal death rate,
bN dN bN b0 x N dN d0 y
N b0 x N d0 y NSubstituting K
for N at equilibrium and r for b0 d0
r (x y) K or K r/(x y)
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Derivation of the Logistic Equation Derivation
of the VerhulstPearl logistic equation is easy.
Write an equation for population growth using
the actual rate of increase rN
dN/dt rN N (bN dN) N
Substitute the equations for bN and dN into
this equation dN/dt
(b0 xN) (d0 yN) N
Rearrange terms,
dN/dt (b0 d0 ) (x y)N) N
Substituting r for (b d)
and, from above, r/K for (x y), multiplying
through by N, and rearranging terms,
dN/dt rN
(r/K)N2