By two growth models:

Exponential

Logistic

Rist of increase

r is small if:

high death rates

low birth rates

the rate of population expansion under ideal conditions

G=rN

G = # of new individuals/time

N = # of individuals in population at a particular time

 R = rate of increase (Birth - Death)

Density - dependent controls = competitiion for recources, disease, depends on population size

Density - independent controls = density not important, abiotic factors (floods, tornado, humiity)

Possible extinction

Few survivors

example: drought make resources very scare, so the population decreases

Population growth rate will be small when population size is eaither large or small

population growth rate will be highest when population is at intermediate level relative to K

At low population levels, if resources are abundant, the population is able to grow exponentially

K is the number of individuals in a population that the environment can maintain without being destroyed

Density - dependent controls are important for K strategists

Density independent conrols are important for R strategist