When pavement ants (the little reddish brown ants you see in sidewalk cracks) have intra-species war they use the concept of a one-to-one correspondence to determine who has a larger army.
Ants pair off locking jaws with another ant of similar size.
Any leftover ants from the larger colony will gang up two on one against the other colony.
Then based on things only ants know either they all go home OR one colony overwhelms the other.
But most of the time only a few ants die.
@futurebird What does “overwhelm” mean?
The notion of “counting” by pairing up is kinda amazing.
The purpose of these battles... what initiates and ends them, is unknown. There are some theories. The simple one is that the winners take over some of the foraging territory of the losers, but observations don't totally support this.
Another idea is that it's all about heated patches of sidewalk. The space under the warm rock is ideal for raising alates and the battles occur in the lead up to nuptial flights. The ants take over the heated nesting spot under the battlefield.
In the wild they would have fought over flat rocks that rested in the sun. By making sidewalks we have given them an endless paradise, but even so, some tiles are more desirable than others since they get better sun, or maybe there is a sprinkler! Very fancy digs!
Tetramorium immigrans have been called habitat specialists. Normally in a wild forest flat rocks on well drained soil in the sun would be rare and the "wars" may have evolved to decide who gets to keep the rock. But sidewalk ants both have pretty good homes, though one might be a bit warmer, so they pair up find out they are both very numerous and similar in size and then go home.
The first Tetramorium immigrans queen to find a sidewalk must have been amazed.
The paper I'm reading attributes the tremendous success of Tetramorium immigrans in part to their low causality "wars" they aren't the only ants that do this. Meat Ants in Australia and Dynomyrmex gigas (one of the largest ants in the world) also have ways of pairing off and sizing each other up that don't involve ants trying to kill each other.
And they could easily kill each other, ants are omnivorous predators. But when two ants of a similar size fight both can end up dead.
@futurebird So we don’t know what the consequences of winning/losing actually are?
I really find these ants astounding — they live in urban settings, in the hard-packed dirt under concrete slabs, and they seem to thrive.
It really is amazing, isn't it.
Such pairing up is what the set theorist of the 19th century did when they defined the "size" of a set by matching two sets element-by-element, and here we see that these ant colonies had used the same definition all along! And doing so saved lives! Brilliant.
myrmepropagandist
Michael Gemar
Tattie
the roamer