Research finds spiders that move by themselves, as opposed to with a group, have higher survival rates
Date: October 7, 2016
Source: University of California - Riverside
A spider looking to immigrate to a different environment is three to four times more likely to survive if it goes by itself, as opposed to as part of a group.
"This is a pretty surprising result that breaks from long-held intuitions that moving as a group would enhance survival rates (for social organisms)," said Jessica Purcell, an assistant professor of entomology at the University of California, Riverside, who is a co-author of a just-published paper on the topic.
One possible reason that individual spiders fare better than groups is that singleton immigrants entering an existing colony of natives are less likely to throw off the colony traits that determine colony survival. In this case, the trait that appears to be most important in determining colony survival is maintaining the right mixture of docile versus aggressive 'personality types' within the colony. The researchers plan to perform additional tests to distinguish between this and other possible causes of this pattern.
Local adaptation of animals has long been a central topic in ecology and evolution because adaptive, specialized traits can allow species to expand into new environments, which in turn can help promote diversification.
The research here focused on the species Anelosimus studiosus, which is found in temperate and tropical areas in North America and South America. It is one of about 30 species of spider, of more than 40,000, that is social, meaning it lives long-term with others of the same species.