Topic 11: Population Growth Flashcards
Population size is influenced by: (4)
death, birth, immigration, emigration
dN/dt =
N/T = B-D
b =
per capita birth rate
B/N
d =
per capita death rate
D/N
r =
per capita growth rate
b-d = (B-D)/N
Rmax
intrinsic rate of increase
- always positive and constant
Formula for exponential growth
Nt = N0(1+rmax)^t
________ rmax = more reproduction (r-selected)
increase
exponential growth curves ____ reach maxima
never
What limits population growth? (5)
- temperature (affects metabolism and E produced)
- precipitation
- predators
- disease
- food availability
When N > K, r = _________ and population _____ back down to K
negative; shrinks
Carrying Capacity (K)
r changes as N approaches K
- maximum population size of an organism that an ecosystem can support indefinitely
growth rate _______ as N approaches K
decreases
the growth rate is ____ than ideal when r is less than rmax
less
How does r change with N in logistic population growth? (graph slope?)
decreasing slope
When N<K, r ___ 0
> , greater than
When N>K, r ____ 0
<, less than (negative)
When N=K, r ___ 0
=, equals
What is the inflection point on a logistic N v. Time curve?
K/2
Equation for logistic growth:
Nt+1 = Nt(1+rt)
Population growth is influenced by:
density-dependent and independent factors
Density-dependent factors:
biotic:
- food availability
- shelter
- mates
- predation
- disease
density-dependent factors have an ________ effect as N increases
increasing
Density-independent factors:
abiotic:
- temperature
- precipitation
- light
- disturbance (ie. fire, flood etc.)
density-dependent factors ______ have an effect on N
always
How do life history strategies influence population growth of r-selected species?
- live in environments with high disturbance
- early maturing
- stay @ bottom of the curve
- low survivorship
- high fecundity
- semelparious
- fast growth
- low population
How do life history strategies influence population growth of K-selected species?
- live in environments with low disturbance
- fluctuate near K
- stay at top of curve
- high survivorship
- lower/more stable growth
- iteroparous
- low fecundity
- can survive extremes
- large population-
crowding (density dependent factor) influenceS:
growth rate, adult size, and survival rate
Body mass vs. time graph
increasing growth rate
mass per plant vs. density graph
decreasing
% survival vs. age graph
decreasing
