I'm hoping this might be an appropriate place to ask for help in examining the rise and fall of a fantasy species I have in mind for a work of fiction. Ultimately I would like to be able to create a spreadsheet that allows me to plug in different numbers to produce a chart that will show the growth and decline of this race over time.
My species (and this is fantasy, remember) reproduces asexually. At year 0 one of these beings literally comes into existence. It is incredibly long lived (a variable; about 3000 years) and during its many fertile years (variable; a %age of its total lifespan) produces many offspring (variable; maybe one every 2-3 years).
These offspring, however, are not so long lived (a %age decline; maybe 2800 years) and don't produce as many offspring (a smaller %age decline).
I'm leaving out a lot of potentially relevant details (plague, famine, war, etc.), but just getting the basic shape of this on a chart will really help me fill out the backstory.
Apologies if this is all really basic / not appropriate for this SE. Needless to say, I'm out of my depth and would be very grateful for any help.