Oh How Wrong We Were About the Evolutionary Tree of Life

Oh how wrong we were about the evolutionary tree of life

If you seem different from your loved ones, you may have felt estranged from your family. As a kid, during particularly stormy falls, you might even have hoped it was a sign of adoption.

As our new research shows, looks can be deceiving when it comes to family. New DNA technology is disrupting the family trees of many plants and animals.

Primates, to which humans belong, were once considered close relatives of bats due to some similarities in our skeletons and brains. However, DNA data now puts us in a group that includes rodents (rats and mice) and rabbits. Surprisingly, bats turn out to be closer to cows, horses and even rhinos than they are for us.

Scientists in Darwin’s day and for most of the 20th century could only determine the branches of the evolutionary tree of life by examining the structure and appearance of animals and plants. Life forms have been grouped according to similarities believed to have evolved together.

About three decades ago, scientists began using DNA data to build “molecular trees.” Many of the first trees based on DNA data were at odds with classical trees. Sloths and anteaters, armadillos, pangolins (scaly anteaters), and aardvarks were once thought to belong to a group called edentulous (“toothless”) because they share aspects of their anatomy. Molecular trees showed that these traits evolved independently in different branches of the mammalian tree. It turns out that aardvarks are more closely related to elephants, while pangolins are more closely related to cats and dogs.

Come together

There is another important source of evidence that was familiar to Darwin and his contemporaries. Darwin noted that animals and plants that seemed to share the closest common ancestry were often found close to each other geographically. The location of species is another strong indicator of their relatedness: species that live in close proximity to each other are more likely to share a family tree.

For the first time, our recent post cross-location, DNA data and appearance for a range of animals and plants. We looked at appearance-based or molecule-based evolutionary trees for 48 groups of animals and plants, including bats, dogs, monkeys, lizards, and pines. Evolutionary trees based on DNA data were two-thirds more likely to match the location of the species compared to traditional evolutionary maps. In other words, the previous trees showed that several species were related based on their appearance. Our research showed that they were much less likely to live next to each other compared to species linked by DNA data.

It may seem that evolution constantly inventing new solutions, almost without limits. But he has fewer tricks up his sleeve than you might think. Animals can look surprisingly similar because they have evolved to do similar work or live the same way. The extinct birds, bats and pterosaurs have, or had, bony wings to flybut their ancestors all had front legs for walking on the ground.

Similar wing shapes and muscles have evolved in different groups because the physics of generating thrust and lift through the air is always the same. He is much the same with the eyeswho may have evolved 40 times in animalsand with only a few basic “designs”.

Our eyes resemble the eyes of squids, with a lens, iris, retina and visual pigments. Squids are closer to snails, slugs and clams than we are. But many of their mollusc relatives have only the simplest eyes.

Moles have evolved as blind, burrowing creatures at least four times, on different continents, on different branches of the mammalian tree. Australian marsupial moles (more closely related to kangaroos), African golden moles (more closely related to aardvarks), African mole rats (rodents), and Eurasian and North American talpid moles (beloved by gardeners and more closely related to hedgehogs that these other “moles”) have all evolved down a similar path.

The roots of evolution

Until the advent of cheap and efficient gene sequencing technology in the 21st century, looks were usually all evolutionary biologists had to do.

While Darwin (1859) showed that all life on Earth is linked into a single evolutionary tree, he did little to trace its branches. Anatomist Ernst Haeckel (1834-1919) was one of the first to draw evolutionary trees that attempted to show how major groups of life forms are related.

Haeckel’s drawings made brilliant observations about living things that influenced art and design in the 19th and 20th centuries. His family trees were almost entirely based on the appearance and development of these organisms as embryos. Many of his ideas about evolutionary relationships have been maintained until recently. As it becomes easier and cheaper to obtain and analyze large volumes of molecular data, many more surprises await.

Matthew Willsprofessor of evolutionary paleobiology at the Milner Center for Evolution, University of Bath

This article is republished from The conversation under Creative Commons license. Read it original article.

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