How far do 2 ant colonies of same heritage have to be in space (and generation) in order to fight? (Kinda follow-up to this.…) I've heard before that if you put 2 ant colonies side by side they're going to attack each other. But then from the previous question, there could be "sister" ant colonies which (assumingly) don't harm one another. I can probably see that generation-by-generation colonies would just naturally be either too far apart in space, (or too close in "generation"), to have any fights. But what actually makes ants decide whether to fight or to not? And whatever it is, is it a spectrum or a limit..? (i.e would there be a case in which _some ants_ of a colony will fight and some wont?)

Space and generation don't directly affect whether ants fight, that's all regulated with pheromones. Some ant species are more tolerant of different smells than others (see the argentine supercolonies mentioned above) while some species of ant have 'rival' nests that they are particularly aggressive to.

So I guess the answer is 'it depends'. On pheromones produced by the queen, and species. And probably diet/weather/local food availability/ some other things I haven't thought of.

I don't think it's possible for some ants of a colony to fight and others not to, but I don't have any evidence to back that up specifically.