Elephant Shrew

Convergent evolution has fooled us: Most of our evolutionary trees can be wrong

Elephant Shrew

Elephant snails are more closely related to elephants than they are to bats, according to molecular evolutionary trees.

An evolutionary tree, or phylogenetic tree, is a branch diagram that shows the evolutionary relationships between different biological species based on similarities and differences in their characteristics. Historically, this has been done with the help of their physical properties – the similarities and differences in the anatomy of different species.

But advances in genetic engineering now allow biologists to use genetic data to decipher evolutionary relationships. According to a new study, researchers find that molecular data lead to very different results, sometimes overturning centuries of scientific work in classifying species according to physical characteristics.

New research led by researchers at the Milner Center for Evolution at the University of Bath suggests that determining evolutionary trees in organisms by comparing anatomy rather than gene sequences is misleading. The study, published in the journal Communication Biology May 31, 2022 shows that we often need to overthrow centuries of scientific work that classified living things according to their appearance.

“It means that 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 tried to reconstruct the animals’ “family trees” by carefully examining differences in their anatomy and structure (morphology).

But with the development of rapid genetic sequencing techniques, biologists can now use genetic (molecular) data to help put together evolutionary relationships for species very quickly and cheaply, often proving that organisms we once thought were closely related actually belong in completely different branches of the tree.

For the first time, researchers at Bath compared evolutionary trees based on morphology with those based on molecular data and mapped them by geographical location.

They found that the animals grouped by molecular trees lived closer geographically than the animals grouped by the morphological trees.

Matthew Wills, professor of evolutionary paleobiology at the Milner Center for Evolution at the University of Bath, said: “It turns out we have many of our evolutionary trees wrong.

– For over a hundred years, we have classified organisms according to how they look and are composed anatomically, but molecular data often tell a completely different story.

“Our study statistically proves that if one builds 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 known to Darwin and his contemporaries.

“For example, small elephant snails, earthworms, elephants, golden moles and swimming manatees have all come from the same large branch of mammalian evolution – even though they look completely different from each other (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.”

Molecular evolutionary trees Elephant Shrew

Molecular evolutionary trees show that elephant snails are more closely related to elephants than they are to bats. 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 than biologists previously thought.

Professor Wills said: “We already have many famous examples of convergent evolution, such as flying that develops separately in birds, bats and insects, or complex camera eyes that develop separately in octopus and humans.

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

“People who support themselves as lookalikes are usually not related to the celebrity they pretend to be, and individuals within a family do not always look the same – it’s the same with evolutionary trees as well.

“It proves that evolution just keeps reinventing things and comes up with a similar solution every time the problem arises in another branch of the evolutionary tree.

“It means that 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 journal, said: “The idea that biogeography can reflect evolutionary history was a big part of what led Darwin to develop his theory of evolution through natural selection, so it’s quite surprising that it had.” t really considered directly as a way to test

accuracy
How close the measured value corresponds to the correct value.

“data-gt-translate-attributes =”[{” 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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