Untangling Spiders' Evolutionary Past: Largest Ever Genetics Study Reveals Spider Origins

How did spiders first evolve? That's a good question. For years, scientists believed that they had the answer but now, researchers have found out that a long-standing theory of spider evolution may actually be false.

In the past, researchers believed that as insects became more and more diverse, spiders evolved new hunting strategies. This included the ability to weave orb-shaped webs to trap their prey. From this single origin, the orb-weaver spiders diverged along different evolutionary paths, leading to the spiders of today. Yet it turns out that this may not be the case.

In earlier studies, researchers relied on just a handful of genes to draw the spider evolutionary tree. While earlier analyses suggested that spiders with orb webs didn't form a group since they appeared in different places along the phylogenetic tree, the genes that were being used weren't enough to elucidate the evolution of a diverse group like spiders.

Now, though, researchers have used some new technology in order to learn a bit more about spiders. The scientists examined two different groups of orb-weaver spiders, as well as several other species. Using thousands of genes, they conducted a comparative phylogenetic analysis. More specifically, the sequenced the genes from 14 different spiders, creating the largest genomic data set for the study of spiders.

So what did they find? It turns out that while the two groups create very similar webs, their strategies for using them, how they manufacture silk and even the silk used to construct the webs are very different.

"Their behaviors are very different, the types of silk are very different-it's my bet that these would be two separate evolutions of a similar structure of web," said Gonzalo Giribet, one of the researchers, in a news release. "But we need to further test it, and we are now looking to expand this study to include as many as 150 different spiders."

The findings are published in the journal Current Biology.