Tech & Science

How Do Different Species Evolve? Spiders on Hawaii Reveal Surprising Phenomenon

Scientists have figured out a fascinating mystery of evolution by showing that different species will evolve in similar, predictable ways even if they have no contact with one another. This trait is a characteristic of adaptive radiation, and better understanding how it works will help scientists better grasp the theory of evolution.

Stick spiders first came to the Hawaiian Islands about 2 to 3 million years ago, Phys. Org reported. Every time a spider traveled to a new island, it evolved into several different species—but at first glance, you wouldn’t know this. That’s because all 14 different species of stick spiders spread throughout the eight Hawaiian islands evolved only three different colorings: red and yellow; black; or matte white. It seems that evolution has repeated the same colorings over the course of many millions of years and occuring in several different isolated islands.

Now, a new study from the University of California, Berkeley, gives insight into how species evolved to look the same despite being in different locations and being genetically different. These different species of spiders are ecomorphs, a word used to describe animals that look the same and live in the same enviroment, but aren't closely related. The new study suggests that ecomorphs, such as these spiders, have a preprogrammed switch in their DNA that allows them to evolve quickly, but also limits what they are able to evolve into, specifically in reference to their coloring.

"They don't evolve to be orange or striped. There isn't any additional diversification," said Rosemary Gillespie, professor and Schlinger chair in Systematic Entomology at UC Berkeley and lead author of the paper, in a statement

In other terms, some parts of evolution may be programmed to be predictable and repeat themselves over and over. This explains why yellow and red stick spiders evolved independently on nearly all the islands, despite not being genetically related. This is why a red and yellow spider on Maui is more closely related to a brown spider on Maui than it would be a similar looking red and yellow spider on another nearby island.

spider A species of Ariamnes from Molokai, part of the Hawaiian Archipelago. A new study from the University of California, Berkeley, gives insight into how species evolved to look the same despite being in different locations and being genetically different. George Roderick

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"This very predictable repeated evolution of the same forms is fascinating because it sheds light on how evolution actually happens," said Gillespie, Phys. Org reported. "Such outstanding predictability is rare and is only found in a few other organisms that similarly move around the vegetation."

The finding better explains the concept of adaptive radiation, where a species evolves quickly, rapidly diversifies and evolves new adaptations. This allows organisms to evolve and adapt to new environments and hardships, and is a cornerstone of evolution. The research on spider evolution also helps biologists better understand the wealth of biodiversity in the Hawaiian islands.

“We need everyone to understand what's there [in Hawaii] and how extraordinary it is,” said Gillespie in a statement. “And then we need to see what we can do to protect and conserve what still waits to be described."