

by Matthew Chin



by Stuart Wolpert

Why do so many animal species — including fish, birds and insects — display such rich diversity in coloration and other traits? In new research, Gregory Grether, UCLA professor of ecology and evolutionary biology, and Christopher Anderson, who recently earned his doctorate in Grether's laboratory, offer an answer.
At least since Charles Darwin, biologists have noticed that species differ in "secondary sexual traits," such as bright coloring or elaborate horns, Grether said. Darwin attributed this diversity to sexual selection, meaning the traits increased an animal's ability to attract mates.But Grether and Anderson, writing in the Oct. 28 issue of the journal Proceedings of the Royal Society B: Biological Sciences, emphasize another evolutionary factor.

Researchers from the United States and Slovenia have discovered a new, giant Nephila species (golden orb weaver spider) from Africa and Madagascar and have published their findings in the Oct. 21 issue of the journal PLoS ONE. Matjaž Kuntner, chair of the Institute of Biology of the Slovenian Academy of Sciences and Arts and a Smithsonian research associate, along with Jonathan Coddington, senior scientist and curator of arachnids and myriapods in the Department of Entomology at the Smithsonian’s National Museum of Natural History, also reconstructed size evolution in the family Nephilidae to show that this new species, on average, is the largest orb weaver known. Only the females are giants with a body length of 1.5 inches (3.8 centimeters) and a leg span of 4 - 5 inches (10 - 12 centimeters); the males are tiny by comparison. More than 41,000 spider species are known to science with about 400 - 500 new species added each year. But for some well-known groups, such as the giant golden orb weavers, the last valid described species dates back to the 19th century. 

Written by Nicole Giese




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