BIO LECTURE NOTES
(3/6/09)
•
Population ecology
•
In crowded populations, survival and fertility decline
o
Food affects both survival and fecundity
•
Space is the important limiting resource for some populations
•
Densityregulated populations do not grow without bound
o
Population rate high = reproductive rate declines
Linear decline per capita
•
Logistic equation
o
In an analogy to exponential growth let Nt+1 = λ (Nt)Nt
o
A simple assumption is that the percapita rate of reproduction changes
linearly with density so, λ(Nt) = 1+r(rNt/K)
o
1+r is the yintercept and –r/K is the slope
o
from this we arrive at the logistic equation, Nt+1 = {1+r(rNt/K)Nt (rate
population growth in terms of density)
when Nt is equal to K, then the population size does not change over
time
o
r is called the intrinsic rate of increase and K is called the carrying capacity
•
population dynamics with the logistic equation
o
K is an equilibrium of the logistic
o
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '08
 JOHNSON
 Biology, Demography, Population Ecology, per capita, Population Growth Rates

Click to edit the document details