Predators predetermine the finding of Nemo

If you can’t find Nemo, try looking where the anemones hang out. They’ve become great friends in what Australian researchers say is a classic example of “interspecies mutualisms”.

“Clownfish live in and around anemones, helping drive off the anemone’s predators and providing it with food, while in exchange the anemone provides protection with its stinging tentacles,” says biologist William Feeney from the University of Queensland (UQ).

“Clownfish have evolved to resist the stings of the anemone, so it ends up being a very beneficial relationship for both species.”

Feeney, with other researchers from UQ and from Deakin University in Victoria, says the interaction helps explain how natural selection has shaped global patterns of biological diversity. Their findings are presented in a paper published in the journal Ecology Letters.{%recommended 6178%}

“We tested and confirmed a very basic and intuitive – but logistically difficult – idea in evolutionary ecology,” he notes. 

“In a nutshell, we were looking to find out whether external pressures, such as predators, can explain the repeated evolution of these kinds of mutually beneficial partnerships.”

The research, which combined genetic analysis with field experiments in French Polynesia, found that fish-anemone mutualisms have evolved at least 55 times across 16 fish families over the past 60 million years.

“This is much more common than previously thought. Over a quarter of coral reef-associated fish families have at least one species that associates with anemones,” says co-author Rohan Brooker.

The researchers say the study suggests predation can explain the independent evolution of cooperative behaviours between species, and that this evolutionary pattern could apply globally.