January 24, 2011

Spiders Modify Mating Signals According To Environment

New research from the University of Cincinnati shows that when male wolf spiders are courting, they can modify their mating signals depending on the environmental surface in order to ensure that their message gets through.

The researchers said that the wolf spiders are leaving little to chance when it comes to increasing their opportunities to successfully mate.

Male wolf spiders adjust the modes of their signaling depending on the habitat on which they find themselves in order to improve the chances of getting the right message across.

The team placed wolf spiders in laboratory containers on natural habitat substrates including soil, rock, wood and leaf litter for equal amounts of time.

The team found that males signaling through vibrations on leaf litter were more than twice as successful in getting females to mate as were males signaling through vibrations on other substrates.

Males signaling vibrations on leaf litter successfully attracted a mate over 85 percent of the time.  The team said that males sending mating cues while positioned on the environmental surfaces successfully attracted a mate less than 30 percent of the time.

According to the researchers, when spiders were given a choice of occupying any of the four substrates types, males and females visited all four but remained twice as long on leaf litter versus other substrates.  This increases their opportunities for successful mating due to the efficacy of communication on leaf litter.

"Importantly, this indicates that the spiders likely recognized the difference between habitats and the efficacy of signaling via vibrations on leaf litter," said researcher Shira Gordon in a press release.

Researchers used a highly sensitive lair vibrometer instrument capable of detecting the barely perceptible vibration signals of wolf spiders to measure

The team said that the males use these signals through body bounces and stridulation on these environmental surface substrates .

While male spiders continued the leg traps and body bounces on surfaces that transmit faint or no vibrations, the researchers said that the males also altered their communications to produce significantly more visual signals when placed on soil, rock or wood substrates versus leaf-litter substrate.

George Uetz, a U.C. professor of biology who lead the research, wrote in the journal:  "In other words, when the seismic signals aren't working due to the environment, male wolf spiders have the ability to vary their signals and shift to another communications mode. They then put more effort into another channel, this being visual cues, in order to get the desired response. We can think of it as going to plan B."

He also said that behavioral flexibility has been considered a hallmark of vertebrate animals but not invertebrates.

"These findings suggest that invertebrates have more ability to modify their behavior than has been traditionally thought to be the case. This ability enables them to compensate for the impact that an animal's environment has on its ability to communicate," said Uetz.

The research was published in the February 2011 issue of the journal "Animal Behavior."


On the Net: