[R-sig-eco] Functional response type II question, curve fitting and

[Luis Fernando García Hernández]

Dear all,

I am new on the list and on the more complex applications of R, so I ask
you to excuse me if my mail is too long.

This time I have to do several tasks related tu functional reponse. I want
to evaluate the relationship between prey density (x) vs prey consumed(y)
the idea is to fit the data set to the functional reponse equation:
 Na/TP=a/(1+aThN). I have idea about the value of most of the equation
parameters, but I am completely lost about how to fit the data points to
this equation.

On another hand I have to graph and compare if there are significative
differences on estimated parameters of the curves for lepidopterans and
ants, the final data should look like the attacher picture.If any of you
have some idea about how to do this, would be really appreciated.

Below you  can find the data and the pictures.

Thanks in advance

    Prey Density Eaten  Lepidopteran 1 2  Lepidopteran 1 3  Lepidopteran 1 3
Lepidopteran 3 4  Lepidopteran 3 5  Lepidopteran 3 4  Lepidopteran 5 7
Lepidopteran 5 5  Lepidopteran 5 6  Lepidopteran 10 8  Lepidopteran 10 10
Lepidopteran 10 7  Ant 1 3  Ant 1 1  Ant 3 4  Ant 3 2  Ant 5 4  Ant 5 6  Ant
10 5  Ant 10 6