June 15 (UPI) -- Fish don't have to be closely related to be doppelgängers. New research out of Australia shows many distantly related fish species still look and act alike.
Scientists at James Cook University looked at anatomical and feeding patterns among a variety of fish species native to Australia. They discovery a surprisingly large number of commonalities.
"The study highlighted some really striking similarities in characteristics like tooth and jaw structure and body shape between Australian freshwater grunters and several other marine fish families when they share feeding habits," Aaron Davis, marine ecologist at JCU, said in a news release.
Convergent evolution describes the adoption of similar anatomical features with similar biological functions by species from different families -- features that weren't present among their most recent common ancestors.
In analyzing the body forms of Australian freshwater terapontid grunters and several distant relatives -- lineages separated by as much as 50 million years of evolution -- Davis and his colleagues identified several examples of convergent evolution.
"We don't have lots of the freshwater fish families we see elsewhere because of our long geographic isolation from other continents," Davis said. "Most of our freshwater fish have actually evolved from marine fish groups that have invaded and adapted to Australian freshwaters over millions of years."
Scientists have identified many examples of convergent evolution, but the latest study showcases the evolutionary phenomenon across a broader range of habitats, as well as longer time scales.
Researchers shared their findings in the journal Proceedings of the Royal Society B.