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Reproductive Potential
Overview
insect pop'ns undergo major fluctuations ...
endemic ... epidemic ... endemic
2 major forces
↗ reproductive potential
↘ environmental resistance
Calculation
standard equation
dN / dt
change in pop over change in time
N*(r)^n
N = original pop'n
r = product of fecundity (=capacity to produce young)
max eggs per female (2nd def'n of fecundity)
proportion of females
polyembyony
n = number of generations
Doug's version
N * (esp)^n
N = original pop'n
e = eggs ... MAX eggs under ideal conditions
s = "sex factor, by Revlon" (% females)
p = polyembryony (babies/egg)
n = number of generations
should be able to
provide formula
stick numbers in the formula
if simple, calculate result
example
starting po'n =4, eggs/female=20, 50% female, 1egg=1baby, 2 generations
N(esp)^n
4*(20*0.5*1)^2
4*(10)^2
4*100
400
spruce budworm
N = 2
e = 359
s = 0.5 (50% female)
p = 1 (1 larva per egg)
n = 1
2 * (359 * 0.5 * 1) ^1
359
n = 4
2 billion
some wasp
N = 2
e = 359
s = 0.5 (50% female)
p = 4 (4 larva per egg)
n = 1
1,436
n = 4
26 billion
balsam wooly adelgid
N = 2
e = 248
s = 1.0 (100% female)
p = 1 (1 larva per egg)
n = 1
496
n = 4
7 billion
Actual Reproduction
factor in mortality/survival ... environmental resistance
need to apply a "survival factor" ... % survive to reproduce
N*(espn*S)^n
e.g mortality ... 5% Survival ... 0.05