Do all individuals in a species have to be identical?

Question

how much variation should accept between individuals "within" a species?

Assume Caminalsules are all adult, there is no difference visible between "male" or "female", have no information on habitat or behavior.

Answer 1

The basic rule of thumb is this; A species is a group of interbreeding individuals. If they for physical or behavioral reasons don't mate, and don't produce fertile offspring, they aren't the same species. Which is to say they have to be physically capable of mating, their natural behavior is to do so, and with the capacity to produce fertile offspring.

Answer 2

yes. they have to be some what identical to reproduce next generation.

otherwise species would icolate so easily