Most of our evolutionary trees may be wrong

elephant

According to the molecular evolutionary tree, elephant shrews are more closely related than elephants.

An evolutionary tree, or phylogenetic tree, is a branching diagram that shows the evolutionary relationships between different biological species based on similarities and differences in their characteristics. Historically, this was done using their physical characteristics—similarities and differences in the anatomy of different species.

However, advances in genetic technology now enable biologists to use genetic data to understand evolutionary relationships. Scientists are discovering that molecular data is leading to very different results, sometimes overturning centuries of scientific work in classifying species by physical traits, according to a new study.

New research led by scientists at the Milner Center for Evolution at the University of Bath shows that determining the evolutionary trees of organisms by comparing anatomy rather than gene sequences is misleading. This study published in the journal communication biology On May 31, 2022, it shows that we often need to reverse centuries of scholarly work that classifies living things by how they look.

“That means convergent evolution has been fooling us – even the smartest evolutionary biologists and anatomists – for over 100 years!” , Matthew Wills

Since Darwin and his contemporaries in the 19th century, biologists have been attempting to reconstruct the “family tree” of animals by carefully examining differences in their anatomy and structure (morphology).

However, with the development of rapid genetic sequencing techniques, biologists are now able to use genetic (molecular) data to help piece together evolutionary relationships for species very quickly and cheaply, often proving that organisms that have What we once thought to be closely related are actually completely different. tree branches.

For the first time, scientists in Bath compared evolutionary trees based on morphology to trees based on molecular data and mapped them by geographic location.

They found that animals grouped together by molecular trees lived more closely together geographically than animals that used morphological trees.

Matthew Wiles, Professor of Evolutionary Paleobiology at the Milner Center for Evolution at the University of Bath, said: “It turns out that a lot of our evolutionary trees are wrong.

“For more than a hundred years, we have been classifying organisms by how they look and are physically put together, but molecular data often tells us a different story.

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

“Where things live – his biography – is an important source of evolutionary evidence that was familiar to Darwin and his contemporaries.

“For example, the tiny elephant shrew, aardvark, elephant, golden mole, and swimming manatee all came from the same major branch of mammal evolution—despite the fact that they look completely different from each other (and very live in different ways).

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

molecular evolutionary tree elephant sly

Molecular evolutionary trees show that elephants are more closely related to elephants than to elephants. credit: Danny Ye

The study found that convergent evolution—when a trait develops separately in two genetically unrelated groups of organisms—is much more common among biologists than previously thought.

Professor Wills said: “We already have many well-known examples of convergent evolution, such as birds, bats and insects developing distinct flight, or squid and humans developing distinctly complex camera eyes.

“But now with molecular data, we can see that convergent evolution happens all the time – the things we thought were often tucked away on the tree of life.

“People who make a living aren’t usually related to the celebrity they’re impersonating, and individuals in a family don’t always look alike—it’s the same with evolutionary trees.

“This proves that evolution just keeps re-inventing things, with a similar solution each time the problem is encountered in a different branch of the evolutionary tree.

“That means convergent evolution has been fooling us – even the smartest evolutionary biologists and anatomists – for over 100 years!”

Dr. Jack Oyston, Research Associate and first author of the paper, said: “The idea that biology can reflect evolutionary history was a large part of what inspired Darwin to develop his theory of evolution through natural selection. , so it’s surprising that it wasn’t really considered as a method of testing directly[{” attribute=””>accuracy of evolutionary trees in this way before now.

“What’s most exciting is that we find strong statistical proof of molecular trees fitting better not just in groups like Afrotheria, but across the tree of life in birds, reptiles, insects, and plants too.

“It being such a widespread pattern makes it much more potentially useful as a general test of different evolutionary trees, but it also shows just how pervasive convergent evolution has been when it comes to misleading us.”

Reference: “Molecular phylogenies map to biogeography better than morphological ones” by Jack W. Oyston, Mark Wilkinson, Marcello Ruta and Matthew A. Wills, 31 May 2022, Communications Biology.
DOI: 10.1038/s42003-022-03482-x

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