Technology

Most of our evolution trees can be wrong

According to molecular family trees, elephant shrews are more closely related to elephants than to 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 has been done based on their physical characteristics – the similarities and differences in the anatomy of different species.

However, advances in genetic engineering now allow biologists to use genetic data to decipher evolutionary relationships. Scientists have found that molecular data leads to wildly different results, sometimes turning on its head centuries of scientific work classifying species by physical characteristics, according to a new study.

New research led by scientists at the University of Bath’s Milner Center for Evolution suggests that defining the evolutionary trees of organisms by comparing anatomy rather than gene sequence is misleading. The study published in the journal communication biology On May 31, 2022, it shows that we often need to overturn centuries of academic work that has classified living things by their shape.

“This means that convergent evolution has been fooling us – even the smartest 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 “family trees” of animals by carefully examining differences in their anatomy and structure (morphology).

However, with the development of rapid genetic sequencing technologies, biologists are now able to use genetic (molecular) data to piece together the evolutionary relationships of species very quickly and inexpensively, often proving that organisms we once thought were closely related are related to each other, in reality, completely different branches belong to a.

For the first time, scientists in Bath compared phylogenetic trees based on morphology with those based on molecular data and mapped 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 Bath’s Milner Center for Evolution.

“We’ve been classifying organisms by shape and grouping them anatomically for more than a hundred years, but molecular data often tells a slightly different story.

“Our study provides statistical evidence that when you construct an evolutionary tree of animals based on their molecular data, it often better fits their geographical distribution.

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

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

“The Molecular Trees have grouped them into a group called Afrotheria, or so called because they are all from the African continent, so the group fits the biogeography.”

Evolutionary molecular elephant tiger

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

The study found that convergent evolution — when a trait evolves 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 flight evolving separately in birds, bats and insects, or the complex camera eyes evolving 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 far apart on the tree of life.

“People who make a living as impersonators usually have no connection to the celebrity they impersonate, and people within a family don’t always look the same – the same is true for evolution trees.

“It proves that evolution keeps reinventing things, finding a similar solution every time the problem occurs in a different branch of the evolutionary tree.

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

dr Jack Auston, research associate and first author of the article, said: “The idea that biogeography can reflect evolutionary history was a big part of what prompted Darwin to develop his theory of evolution through natural selection, so it is very surprising that this is not the case was considered a really 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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