Population Growth

Age pyramids
– a wide base is indicative of a population growth in the future- developing countries have pyramid shaped graphs- developed countries have straighter graphs (no population growth = population will stay the same)
Population Growth Models (key)
Nt – pop at time tNo – original pop sizeB – # of birthsD – # of deathsI – immigrationE – emigration ? – geometric growth rate, replacement rate or (N(t+1))/Ntr – intrinsic rate of natural increase or B-D per individualk – carrying capacity
General Growth Model
Nt = No + B – D
Geometric Growth Model
Nt = No?^t-discrete breeding-non-overlapping generations
Exponential Growth Model
dN/dt = rN-continuous breeding-overlapping generations-unlimited environmentJ-shaped curve
Logistic Growth Model
dN/dt = rN (K-N /K)-continuous breeding-overlapping generations-limited resourcesS-shaped curve
intraspecific competition
competition for resources w/in your own specie