[R] stochastic models for population growth

[Vassily Shvets]

Hello,
Having measured two populations' characteristics at one particular time[with great precision] with R, I would like to extend this to measuring the same populations starting at t1, and then again at t2, and try to develop a growth model (something like dpop1/dt=r*pop^(...),dpop2/dt=r*pop^(...)). I think the idea is to create a model that will predict the growth of a population(N(mu, sigma)) within a margin of error. This kind of modeling isn't well known or publicized in terms of R, am I right?
regards,
s