Most of our evolutionary trees can be wrong

According to molecular phylogenetic trees, elephant shrews are more closely related to elephants than shrews.

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 features and differences in the anatomy of different species.

But advances in genetic engineering now allow biologists to use genetic data to decipher evolutionary conditions. According to a new study, scientists have found that molecular data lead to many different results, sometimes rejecting centuries of scientific work to classify species based on physical characteristics.

New research led by researchers at the University of Baths Milner Center for Evolution suggests that it is misleading to define the evolutionary trees of organisms by comparing anatomy rather than gene sequence. The study published in the journal Communication Biology May 31, 2022, shows that we often have to overthrow centuries of academic work in which living things were classified according to their form.

“This means that convergent evolution has been fooling us – even the most talented evolutionary biologists and anatomists – for over 100 years!” † Matthew Wells

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

But with the development of rapid genetic sequencing technologies, biologists are now able to use genetic (molecular) data to compose species’ evolutionary relationships very quickly and inexpensively, often proving that organisms we once thought were closely related. was in fact. , belongs to a completely different set of tree branches.

For the first time, researchers in Bath compared phylogenetic trees based on morphology with those based on molecular data, plotting them by geographic location.

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

“It turns out that many of our evolutionary trees are wrong,” said Matthew Wells, professor of evolutionary paleobiology at the University of Baths Milner Center for Evolution.

“For over a hundred years, we have classified organisms based on their shape and grouped anatomically, but molecular data often tell a slightly different story.

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

“The place where things live – their biogeography – is an important source of evolutionary evidence known by Darwin and his contemporaries.

For example, young shrews, pigskins, elephants, golden moles and swimming lakes all come from the same large branch of mammalian evolution – despite the fact that they look very different (and live in completely different ways).

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

Molecular phylogenetic trees show that elephant shrews are more closely related to elephants than shrews. Credit: Danny Ye

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

Professor Wells said: “We already have many famous examples of convergent evolution, such as flights that develop separately in birds, bats and insects, or the complex camera eyes that develop separately in squid and humans.

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

“People who live like imitators usually have nothing to do with the celebrity they imitate, and people in a family do not always look alike – it’s the same with evolutionary trees.

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

“This means that convergent evolution has been fooling us – even the most talented evolutionary biologists and anatomists – for over 100 years!”

dr. Jack Auston, research fellow and lead author of the paper, 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 very surprising that it does not did it. was seen as a very simple method[{” 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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