The power to imagine a better world has helped transform human societies, and it may be doing the same to ant societies.
Individual ants have differences in behaviour – something almost akin to a personality – that affect colony decisions. And some ants are so different in their personal preferences that they may act as the imagination of the colony, driving it on to a better future.
Rock ants (Temnothorax albipennis), found in coastal areas of the UK, make their homes in crevices. If a nest is wrecked, or if scouts find better digs, it often makes sense to relocate.
But not just any crevice will do. When looking for a new home, ants have a high-maintenance list of requirements, says Thomas O’Shea-Wheller at the Ant Lab of the University of Bristol, UK. They seek low light levels, an entrance gap of 1 to 1.5 millimetres, a ceiling height of roughly 2 millimetres and an internal area of about 20 square centimetres. To test how individuals’ opinions of potential nests affect a group decision to relocate, O’Shea-Wheller’s team showed artificial nests that were excellent, good or poor to 160 individual ants from 10 colonies.
In general, the better the nest, the more time the ants spent in it laying down pheromones. These pheromones make other ants more likely to join them.
But the team found a lot of variability between the amount of time individuals spent in a nest of a certain quality. “Some ants are picky, others are more liberal and will accept almost anything,” says O’Shea-Wheller. “Much like humans, not everyone wants to live in a mansion.”
And some ants never seem happy, however nice a nest is. They live there, but seem restless, and are more likely to scout. It means they are always searching for new things. “They are the imagination of the colony,” says O’Shea-Wheller.
“The ability of the colony to find new nest sites depends on there being some wanting to search,” says Anna Dornhaus at the University of Arizona in Tucson. “It’s useful to the colony to have some ants that are fussy.”
The team modelled this behaviour and found that if the colony was choosing between two poor nests, the ants with more extreme behaviour – in this case the ones that would settle for almost anything – helped make the collective decision-making process faster and more flexible (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2016.2237).
“This adds to the evidence that individuality is important,” says Nathalie Stroeymeyt at the University of Lausanne in Switzerland.
However, we still don’t know what’s behind this individuality. “We’d like to know what drives personality differences, what the evolutionary benefits are,” says Dornhaus. “At least this gives us a suggestion about why personality differences could be useful – and could benefit a colony.”
Source: News Scientist