University of Guelph integrative biology professor Ryan Norris has discovered that fruit flies spend less time eating, mate less often and produce fewer offspring when exposed to a predator.
Even the predator’s smell alone can cause population decline. The smaller the prey population is, the greater the risk of extinction.
“This finding has implications for species already endangered and living in smaller populations because it shows they are more vulnerable to predator fear,” Norris says.
“It seems once a population reaches a certain size, fear alone may lead to its extinction.”
Working with McGill University professor Kyle Elliott, Norris found small populations of fruit flies exposed to the scent of a praying mantis were seven times more likely to go extinct.
The researchers suspect that flies feel safety in numbers, as their vigilance increases when numbers decline.
The finding may help explain a long-standing biological conundrum in population size and extinction, known as the Allee effect. The study was published in the journal Proceedings of the Royal Society B.