Elephant shrews are more closely related to elephants than to elephants, according to molecular evolutionary trees.
The evolutionary tree or phylogenetic tree is a branched diagram showing the evolutionary relationships between different species based on similarities and differences in their characteristics. Historically, this has been done with the help of their physical characteristics – the similarities and differences in the anatomy of different species.
However, advances in genetic technology now allow biologists to use genetic data to decipher evolutionary relationships. According to a new study, scientists have found that molecular data lead to very different results, sometimes canceling centuries of scientific work in classifying species by physical features.
A new study led by scientists at the Milner Center for Evolution at the University of Bath suggests that identifying evolutionary trees in 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 repeal centuries of scientific work that classifies living things according to what they look like.
“This means that convergent evolution has been misleading us – even the smartest evolutionary biologists and anatomists – for more than 100 years! “Matthew Wills.”
From Darwin and his contemporaries in the 19th century, biologists sought 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 techniques, biologists are now able to use genetic (molecular) data to help assemble evolutionary relationships for species very quickly and cheaply, often proving that organisms we once thought were closely related, in fact belong to completely different branches of the tree.
For the first time, Bath scientists compared evolutionary trees based on morphology with those based on molecular data and mapped them by geographical location.
They found that animals grouped together by molecular trees live more closely together geographically than animals grouped together using morphological trees.
Matthew Wills, a professor of evolutionary paleobiology at the Milner Center for Evolution at the University of Bath, said: “It turns out that we have mistaken many of our evolutionary trees.
“For more than a hundred years, we’ve been classifying organisms according to how they look and collected anatomically, but molecular data often tells us a very different story.
“Our research proves statistically that if you build an evolutionary tree from 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, little elephants, scumbags, elephants, golden moles and swimming manatees came from the same large branch of mammalian evolution – despite the fact that they look completely different from each other (and live in very different ways).
“Molecular trees have united them into a group called Afrotheria, so called because they all come from the African continent, so the group corresponds to biogeography.
Molecular evolutionary trees show that elephant shrews are more closely related to elephants than to elephants. Credit: Danny Ye
The study found that convergent evolution – when a trait develops separately into two genetically unrelated groups of organisms – is much more common than biologists previously thought.
Professor Wills said: “We already have many well-known examples of convergent evolution, such as flight that develops separately in birds, bats and insects, or complex camera eyes that develop separately in squid and humans.
“But now, with molecular data, we can see that convergent evolution is happening all the time – things we thought were closely linked often end up far from each other on the tree of life.
“People who make a living as doubles are usually not related to the celebrity they pretend to be, and people in the family don’t always look alike – it’s the same with evolutionary trees.
“This proves that evolution simply continues to rediscover things, offering such a solution every time the problem is encountered in a different branch of the evolutionary tree.
“This means that convergent evolution has been misleading us – even the smartest evolutionary biologists and anatomists – for more than 100 years!
Dr Jack Oyston, a research fellow and first author of the paper, said: “The idea that biogeography can reflect evolutionary history was a big part of what prompted Darwin to develop his theory of evolution by natural selection, so it’s quite surprising so far it has not been considered directly as a way to test the accuracy of evolutionary trees in this way.
“The most exciting thing is that we find strong statistical evidence of molecular trees that fit better not only in groups like Afrotheria, but also in the tree of life in birds, reptiles, insects and plants.
“Being such a widespread model makes it much more potentially useful as a general test for different evolutionary trees, but it also shows how widespread convergent evolution has been when it comes to misleading us.
Reference: “Molecular phylogenies compare 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-x03482
Add Comment