Lab: Formulas

Question 1

Index of Dispersion

Answer 1

Or, the variance/mean ratio (symbolized as: s2/ x̄ ) yields a value that is:

around 1
-indicates random dispersion

more than 1
-indicates aggregation

less than 1
-indicates uniformity

(note: a high value of s2/ x̄ means high aggregation [very clumped], but low dispersion [not very spread out])

Question 2

Change/Growth in Population

Answer 2

∆N(t) = N(t) (r) ((K-N) / K)

Question 3

Prey Growth Equation

Answer 3

∆H = rH - pHP
where, r = rate of reproduction
H = prey population
P = predator population
p = predation constant

Question 4

Predator Growth Equation

Answer 4

∆P = apHP - dP
where, P = predator population
a = birth constant (“not on test, but know”)
H = prey population
d = percentage pf individuals in a predator population that die between generations
p = predation constant

Question 5

Holling’s Disc (Catch-rate) Equation

Answer 5

Catch-rate = (A N) / (1 + T(h) AN)
where, C = number of prey captured
A = the attack rate
N = prey population
T(h) = handling time

Question 6

Competition Growth

Answer 6

∆N1 = (r1) • (N1) • ((K1 - N1 - αN2) / K1)

where, ∆N1 = change in population size from one time interval to the next
r1 = pop growth rate of species 1
N1 = pop size of species 1
N2 = pop size of species 2
α (alpha) = the effect of species 2 on species 1
K1 = carrying capacity of species 1