# Population Growth problem

1. Jan 27, 2005

### apchemstudent

The population of the wolves influences the change in population of the mooses. When the population of the wolves increase, the mooses' population also increase. From the population growth formula of the wolves

delta N/delta t = rN(K-N)/K

which factor affects the population of the mooses?

a)r

b)N

c)K

d) rN

e)delta t

I picked d) because N represents the initial population, which doesn't affect the population of the mooses if it doesn't change.

r is the rate of change in populations, which can affect it i guess but rN denotes the actual change in population.

K is the carrying capacity of the population of the wolves. It can affect the population of the mooses, but it does not directly affect it( it will result in the change in population of wolves and then change in mooses)

2. Jan 27, 2005

### Moonbear

Staff Emeritus
I agree with your choice of rN, which is the rate of change of the population of wolves. This is the most direct influence since the question states the population of moose increases with the population of wolves.

I would clarify that the carrying capacity, K, is not going to result in a change in the population of wolves either. Instead, it essentially describes the limit at which the population growth will plateau.

Be careful of confusing delta t and dt. Most bio texts don't emphasize this or go into any derivation of the formula, but only use delta t when talking about change in time, the dN/dt in the model for population growth is the result of differentiation. The reason this distinction is important in this question is that delta t would affect the population of moose (both populations would be affected by time), but dt, as a symbol for the differential, doesn't mean anything standing alone.