So that title may be a little sensationalistic… but the web is alive this morning (no pun intended) with stories about an enormous series of interconnected webs spread out over a 200 yard area in North Texas. Researchers and visitors alike have been drawn to the sprawling web, but were uncertain whether it was created by social spiders or one terrifying giant spider with unlimited silk production capabilities and a strong work ethic. Kind of a cross between the queen in Aliens and the giant spider, Shelob, that Frodo fights on his way to Mordor. Turns out the social spider theory was correct!
Identified on Bug Girl’s Blog (where would I be without you?) as the work of the Southeastern Social Cobweb Spider, the web is acting as a massive mosquito trap.
(From CNN) “At first, it was so white it looked like fairyland,” said Donna Garde, superintendent of Lake Tawakoni State Park, about 45 miles east of Dallas. “Now it’s filled with so many mosquitoes that it’s turned a little brown. There are times you can literally hear the screech of millions of mosquitoes caught in those webs.”
Many people are unaware of the existence of social spiders, which comprise about a dozen or so different species, most of which developed independently from one another. Unlike large insect communities where there is a single queen and workers are typically female or sterile, in social spider communties all members can mate. Moreover, it does not appear that the spiders’ roles are functionalized with all members taking part in the full spectrum of pleasant day to day spiderish activities.
Social Spider Bar Mitzvah / A scene from a Hoofnagle nightmare Theridion nigroannulatum (picture from the New Scientist)
Below is an interesting excerpt from an older piece in Science News Online on social spiders concerning their influence on the theory of group selection:
“As biologists have started teasing apart the web of relationships inside spider societies, they have helped rehabilitate a concept called group selection. Once shunned by evolutionary biologists, the idea may be one of the best ways to understand how cooperative social spiders have evolved, says Theo Evans of the University of Melbourne in Parkville, Australia, who studies social spiders in eucalyptus forests.
In classical Darwinian evolution, the most fit individuals of a species survive and reproduce. In the 1960s, theorists suggested group selection as a communal corollary. According to this concept, certain behaviors benefit entire species of animals rather than individuals.
Male deer, for example, compete with each other through nonlethal displays. This type of behavior may have evolved because it led to fewer deaths for the species as a whole rather than to breeding advantages for the individual, suggested adherents of group selection theory.
Although the concept made a certain amount of intuitive sense, it doesn’t generally hold up to evolutionary scrutiny, according to today’s biologists. Groups don’t reproduce, after all. Only individuals do, and individuals compete with their neighbors for food and mates. Moreover, groups are fluid, with individuals moving in and out of them at a rate that would dilute any benefit accrued by temporary team work.
Today, biologists are focusing on evolution at the level of whatever carries a gene, says Evans. In most cases, genes confer advantages on the individual who carries them. In social spiders, however, an entire, inbred group may be the vehicle that carries a gene, proposes Avilés.
The sex ratio among cooperative social spiders supports this theory. Ninety percent of a cooperative spider population is female. This sex ratio benefits colonies in their competition with other colonies, says Avilés.
The more fertile females there are in a nest, the faster the colony grows to a safe, productive size, and the more daughter colonies the group can spin off. However, any individual in a colony could pass its own genes along faster by bearing many males, who could inseminate many females. Thus, the sex ratio appears to be a trait selected at the group level.”
The full article with a lot of other great info can be found here.