Over the course of many millions of years, members of one beetle family have evolved to impersonate army ants at least a dozen separate times, adding to evidence that evolution is more predictable than once thought.

Credit: Munetoshi Maruyama and Joseph Parker

Several species of rove beetle (Staphylinidae; pictured) mimic the appearance, odour and behaviour of particular army ant species in order to infiltrate ant colonies and eat the ants' young. Joseph Parker at Columbia University in New York and Munetoshi Maruyama at the Kyushu University Museum in Fukuoka, Japan, sequenced DNA from 58 rove beetle species — including 37 that disguise themselves as various army ants — from around the world. The researchers analysed this, along with published beetle sequence data, and found that army-ant mimicry has evolved independently between 12 and 15 times in rove beetles all descended from a common ancestor that lived more than 100 million years ago.

The extensive time period over which the different beetle species evolved these similar traits raises questions about the idea that evolution is strongly contingent on chance events, the authors say.

Curr. Biol. http://doi.org/b2vj (2017)