Radical Evolution Isn't as Random as You'd Think
Evolutionary biologists have always wondered if we were to hit that "restart" button, would things still turn out as they have? A new study says that's more than likely, as many species seem to have stumbled upon the same few saving-grace traits on their own accord.
That's at least according to a study recently published in the journal Nature Genetics, which details how an international team of experts set out to investigate the evolutionary history of three groups of aquatic mammals - the same groups that make up whales, walruses, and manatees today.
If you're at all familiar with some prime examples of evolution from the fossil records, you likely know that whales once roamed the land as large wolf-like hunters. Over time, these mammals started spending more and more time hunting for food in the water, until natural selection helped the spread of mutations more suited for aquatic life.
The earliest whale species, looking like long, four-finned orcas, eventually dispersed, changing in shape, size, diet and hunting strategies to become the varied ocean giants we see today.
Interestingly, they were not alone in this radical adjustment to a new way of life. The ancestors of manatees and walruses provide two more examples of terrestrial mammals gone aquatic. (Scroll to read on...)
Evolution is normally described as the consequence of freak mutations winding up helping a species adapt and change. However, the team of 26 contributing researchers from around the world theorized that if all three of these groups experienced the same kinds of genetic tweaks to get to where they are today, then it may be a lot more predictable than originally thought.
They sequenced the genomes of walrus, manatee, killer whales and bottlenose dolphins, comparing how many genes changed independently in each lineage. Unsurprisingly, the random nature of mutation proved itself, with the great majority of these genes being utterly unrelated.
However, in the case of 15 genes, natural selection made the same genetic change occur in all three lineages. This, of course, could be mere consequence, but the researchers suspect something more is at play.
"They we think it's because there's only so much you can change and still be functional," Kim Worley, a genome biologist at Baylor College of Medicine recently told New Scientist.
She explained that because there are only so many ways for a terrestrial animal to adapt to aquatic environment, it may have really limited what kind of mutations could help. All others, predictably, would prove lethal.
And while this limiting effect may not prove so true for less radical changes, it does in part show that even if we hit that restart button, some groups are just bound to do the same thing.
Still, it's important to note that this is all just a theory. A great many more examples will need to be dragged up from genomic and fossil records reaching back to the dawn of life to show whether the team's hypothesis can stand on its own.
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