Although evolution is a widely-accepted concept in the scientific community, some of its aspects haven’t been studied as thoroughly as they should because of how difficult it can be to observe. On the other hand, a recent break may help change that.
Scientists from James Cook University compared various Australian freshwater fish species with distantly-related marine fish species. With up to 50 million years of evolution in between these two kinds of fish, scientists expected to see big differences in their bodies and behavior.
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To their surprise, the fish were more similar to one another than anticipated, which is the result of something called convergent evolution. Convergent evolution is a process where distantly-related organisms evolve with similar traits as a direct consequence of the ecosystem they share, and unfortunately, this process lacks extensive documentation.
In the journal Proceedings of the Royal Society B, the scientists note how the fish they observed exhibited a host of similar qualities to each other despite belonging to entirely different species groups.
"The study highlighted some really striking similarities in characteristics like tooth and jaw structure and body shape between Australian freshwater grunters and several other marine fish families when they share feeding habits," said James Cook University’s Dr Aaron Davis, the lead author of the study.
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Since continental Australia is cut off from the rest of the world, it provided a unique opportunity to learn more about how groups of animals undergo changes to survive in a particular secluded environment.
Examples of both behavioral and cosmetic similarities were present in the samples studied, which were carefully examined using both scanning electron microscopy and X-ray imaging.
"We don't have lots of the freshwater fish families we see elsewhere because of our long geographic isolation from other continents. Most of our freshwater fish have actually evolved from marine fish groups that have invaded and adapted to Australian freshwaters over millions of years," Davis continued.
"It matches our expectations regarding evolution, but we haven't seen this process documented at such broad habitat and time scales all that frequently, so it's quite exciting."
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While the study illustrates a bold proof of concept behind convergent evolution, it also raises a host of new questions. Among those: what caused all these fish develop similar traits? And what other changes can we expect as the environment continues to change?
Follow-up studies could help answer those, while also helping researchers learn about instances of convergent evolution in other kinds of animals.
Source: Science Daily