According to molecular evolutionary trees, elephant shrews are more related to elephants than to shrews.
An evolutionary tree, or phylogenetic tree, is a branching diagram that shows the evolutionary relationships between various biological species based on similarities and differences in their characteristics. Historically, this was done using their physical characteristics: the similarities and differences in the anatomies of various species.
However, advances in genetic technology now allow biologists to use genetic data to decipher evolutionary relationships. According to a new study, scientists are discovering that molecular data are leading to very different results, sometimes turning centuries of scientific work into the classification of species by physical traits.
New research led by scientists at the Milner Center for Evolution at the University of Bath suggests that determining the evolutionary trees of organisms by comparing anatomy rather than gene sequences is misleading. The study, published in the journal Communications Biology on May 31, 2022, shows that we often have to turn around centuries of academic work that classified living things according to how they look.
“It means that convergent evolution has deceived us, even the most intelligent evolutionary biologists and anatomists, for over 100 years!” – Matthew Wills
Since Darwin and his contemporaries in the 19th century, biologists have attempted to reconstruct the “genealogical trees” of animals by carefully examining the 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 gather the evolutionary relationships of species very quickly and economically, often proving that organisms that before we thought they were closely related they actually belong to a completely different relationship. tree branches.
For the first time, Bath scientists compared morphology-based evolutionary trees with molecular data-based ones and mapped them by geographic location.
They found that animals grouped by molecular trees lived closer geographically than animals grouped by morphological trees.
Matthew Wills, a professor of Evolutionary Paleobiology at the University of Bath’s Milner Center for Evolution, said: “It turns out we have a lot of our evolutionary trees wrong.
“For over a hundred years, we’ve been classifying organisms according to how they look and come together anatomically, but molecular data often tells a very different story.
“Our study statistically shows that if an evolutionary tree of animals is constructed from its molecular data, it often adapts much better to its geographical distribution.
“Where they live, their biogeography, is an important source of evolutionary evidence that was familiar to Darwin and his contemporaries.
“For example, the tiny shrews of elephants, aardvarks, elephants, golden moles, and swimming manatees come from the same large branch of mammalian evolution, although they look completely different from each other (and live in very different ways. different).
“Molecular trees have brought them all together in a group called Afrotheria, so named because they all come from the African continent, so the group coincides with biogeography.”
Molecular evolutionary 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 into two groups of genetically unrelated organisms, is much more common than biologists previously thought.
Professor Wills said: “We already have many famous examples of convergent evolution, such as flight that evolves separately in birds, bats and insects, or complex camera eyes that evolve separately in squid and humans.
“But now with molecular data, we can see that convergent evolution is happening all the time; things that we thought were closely related often turn out to be very far away in the tree of life.
“People who make a living as peers are not usually related to the celebrity they impersonate, and individuals within a family do not always look alike; the same goes for evolutionary trees.
“It proves that evolution continues to reinvent things, proposing a similar solution every time the problem lies in a different branch of the evolutionary tree.
“It means that convergent evolution has deceived us, even the most intelligent evolutionary biologists and anatomists, for over 100 years!”
Dr. Jack Oyston, associate researcher and lead author of the paper, said: “The idea that biogeography may reflect evolutionary history was a big part of what drove Darwin to develop his theory of evolution through of natural selection, so it’s quite surprising that he wouldn’t have done it – he hadn’t actually considered it directly as a way to test the accuracy of evolutionary trees in this way before now.
“What’s more exciting is that we find solid statistical evidence that molecular trees fit better not only into groups like Afrotheria, but also into the tree of life of birds, reptiles, insects and plants.
“Being such a widespread pattern makes it much more potentially useful as a general test of different evolutionary trees, but it also shows how widespread convergent evolution has been when it comes to deceiving us.”
Reference: “Molecular phylogenies map to biogeography better than morphological ones” by Jack W. Oyston, Mark Wilkinson, Marcello Ruta and Matthew A. Wills, May 31, 2022, Communications Biology.DOI: 10.1038 / s42003-022-03482-x