This preview shows pages 1–2. Sign up to view the full content.
Population Growth
Population growth
Population: a group of individuals of the same species in the same place
May display two types of growth:
Exponential
Logistic
Exponential growth
: All or a fixed proportion of individuals can reproduce indefinitely
Beehive can’t grow exponentially
Exponential growth
Consider a case where we start with a single cell, and all cells can reproduce
Exponential growth curve
Clearly not linear, an exponential function
(Graph of exponential function)
Exponential growth formula
Growth rate= change in size divided by change in time
(dN/dT)
Growth rate is slope of curve
dN/dT = rN
N = population size
R = the growth constant, or…
R = the increase in size per generation
R is calculated as the difference in the birth rate and the death rate
Exponential growth: by the numbers
Consider what is happening numerically
T
0 1 2 3 4 5
N
1 2 4 8 16 32
dN/dT
1 2 3 8 16
dN/dt increases with increasing N
dN/dt is proportional to N (dN/dt = rN)
Implications
Even with lower r, dN/dt can be actually larger because of the higher N
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.
 Winter '10
 Dr. Bos
 Biology

Click to edit the document details