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We may have family trees all wrong

To discern evolutionary relationships and family trees, biologists focus on physical characteristics (morphology), but this can be tricky. For example, the wings of birds, bats and butterflies may look superficially similar, yet it is not a sign of close relatedness.  

Now, scientists at the University of Bath have managed to use molecular data to reconstruct family trees and to examine the relatedness of organisms. The study, published in the journal Communications Biology, compares the older method with the molecular method for building family trees. 

Interestingly, the research shows that family trees of organisms built by molecular methods are more closely grouped together geographically than those in evolutionary trees based on morphology.    

“It turns out that we’ve got lots of our evolutionary trees wrong,” said Matthew Wills, professor of Evolutionary Paleobiology at the Milner Centre for Evolution. “For over a hundred years, we’ve been classifying organisms according to how they look and are put together anatomically, but molecular data often tells us a rather different story.”

“Our study proves statistically that if you build an evolutionary tree of animals based on their molecular data, it often fits much better with their geographical distribution.”

“Where things live – their biogeography – is an important source of evolutionary evidence that was familiar to Darwin and his contemporaries. For example, tiny elephant shrews, aardvarks, elephants, golden moles and swimming manatees have all come from the same big branch of mammal evolution – despite the fact that they look completely different from one another (and live in very different ways).”

“Molecular trees have put them all together in a group called Afrotheria, so-called because they all come from the African continent, so the group matches the biogeography.”

It makes sense that biogeography might be more important than morphology as something pointing towards relatedness. Similar body parts might develop independently, something called convergent evolution, and a huge red herring in the search for a tree of life.

“We already have lots of famous examples of convergent evolution, such as flight evolving separately in birds, bats and insects, or complex camera eyes evolving separately in squid and humans,” explained Professor Wills.

“But now with molecular data, we can see that convergent evolution happens all the time – things we thought were closely related often turn out to be far apart on the tree of life.”

“People who make a living as lookalikes aren’t usually related to the celebrity they’re impersonating, and individuals within a family don’t always look similar – it’s the same with evolutionary trees too.”

“It proves that evolution just keeps on re-inventing things, coming up with a similar solution each time the problem is encountered in a different branch of the evolutionary tree. It means that convergent evolution has been fooling us – even the cleverest evolutionary biologists and anatomists – for over 100 years!”

By Zach Fitzner, Staff Writer

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