Overall, spiders became shyer after they were disturbed. This result was likely a side effect of the spiders' natural environment, Modlmeier said. Predatory ants that overrun S. dumicola's webs have put the species under threat, and laying low after an attack may increase the spiders' chances of survival.
However, a difference emerged in spiders that spent the entire experiment with the same buddies compared to those that had to integrate with strangers. The spiders that stayed in their colonies became more consistent in their behavior over time, and more divergent from one another. In other words, spiders settled into "bold" or "shy" personalities, and differed very little in how they responded to fake attacks.
In contrast, the spiders that had to cope with new colony-mates were less individualistic and less consistent in their behavior. This is likely because these spiders had failed to find their "niches" in the changing social groups, Modlmeier said.
"It's a huge part of what makes social groups successful and effective," he said. "If you have a very efficient group that works together well, where everyone knows their place and has a task to work on, that group will be much more successful."
The same is likely true for other social insects, and social animals in general, up to and including humans and other primates, Modlmeier said. A few studies have failed to find evidence for social niche specialization in meerkats and stickleback fish, but those results are surprising, he said.
"I would expect to find it in social species, especially species that have close groups where animals live together for a long time," Modlmeier said.
The researchers report their findings today (Aug. 26) in the journal Biology Letters.
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