We distinguish immediately many kinds of Populations:
intelligent creatures: humans, elves, dwarfs, orcs, etc...
animals: rabbits, wolves, bears, eagles, sharks, etc.
undeads
Some difference appear between them. For example, undeads do not reproduce themselves in the same way as other do. And human population are more complex because individuals can have different social functions (guards, hunters, farmers, etc.). Anyway, for the sake of simplicity, we will make the management of these populations uniform.
Another distinction exist between rural and urban Populations. the section called Urban Population of intelligent creatures>