When there are predators nearby, guppies develop stronger and more stable social bonds, according to a new study.
Scientists from the University of Exeter, University of York and University of the West Indies, St Augustine have discovered that Trinidadian guppies (Poecilia reticulata) form stronger relationships if they thought that there are predators nearby. This was the first experimental evidence of such behaviour.
Their findings were published in the Scientific Reports journal. First author Dr Robert Heathcote, of Exeter's Centre for Research in Animal Behaviour, said that the research was important in their understanding of the reasons why social bonds and friendships formed.
"The effects of dangerous environments on social bonds are also known in humans, such as between soldiers who form strong and long-lasting bonds during active duty in war zones," he added.
In this study, the guppies were kept in pools, with some of them being exposed to model predators. The researchers tracked their social ties by observing how often the same individual guppies swam together.
Interestingly, as the social bonds were stronger, the guppies formed smaller groups.
"We suggest this may reflect a conflict between the benefits of forming larger groups and those of forming stronger relationships," said co-author Dr Safi Darden.
Co-author Professor Darren Croft added, “Our new work suggests that living under the threat of predation may have played a key role in the evolution of social relationships, and more work is needed to examine this across species.”