9.2 Population Growth Flashcards
N
population size
N0
initial population size
r
maximum per capita growth rate
t
time
K
carrying capacity
dN/dt
population growth rate
positive growth
births(B) + immigration(I) > deaths(d) + emigration(E)
no growth
B + I = D + E
negative growth
B + I < D + E
exponential growth
dN/dt = rN
how do r and N affect exponential growth?
exponential growth increases as r increases. each individual reproduces more -> more growth
exponential growth increases as N increases. more individuals reproducing -> more growth
logistic growth
dN/dt = rN(K-N / K)
how do r, N, and K affect logistic growth?
logistic growth is highest when N = 1/2 K
logistic growth increases as r increases
logistic growth increases as K increases
density dependent limiting factors
effect is dependent on population density
density dependent examples
competition, predation, disease and parasites, social behaviors
density independent limiting factors
effect is not related to population density
density independent examples
abiotic factors
sunlight, rainfall, natural disasters
