Results of an NSF-funded research partnership involving Alma College biology faculty and students are revealed in an international journal.
When it comes to courting, one common spider species is quick to learn, and that learning process involves eavesdropping on the visual cues of rivals to win their mate.
The latest discovery in a research partnership represented by Alma College, The Ohio State University at Newark and the University of Cincinnati is the featured article in the August 2015 issue of the international research journal, Animal Behaviour.
Previous studies by the researchers explored how the brush-legged wolf spiders (Schizocosa ocreata) used visual eavesdropping to try to outdo a male rival’s leg-tapping mating moves in the wild. In the great outdoors, the males start their show when they smell the pheromones in the silk of a ready-to-mate female.
However, the researchers, using virtual digital technology as part of their study, discovered that courtship behavior becomes a learning experience for male wolf spiders raised in the lab, and they pick it up quickly.
Dave Clark’s passion for studying animal communication using technology-advanced visual displays has taken him many places, from the Alma College-owned bog just a few miles from campus to the Caribbean for Spring Term to the Galapagos Island. Recently, his innovative work on the Galapagos Island involving robotic lizards has received national attention. The video above shows a robotic lizard interacting with a live lizard.
Spiders were observed in a lab with a video of a “virtual” male spider sending out courtship signals in a digital version of a natural habitat. When they were shown videos of other leg-tapping, courting males paired with silk cues from females, they quickly learned to recognize the behavior as part of the courtship process — in as little as four days. Having learned this connection between courtship of others and the presence of a female, the eavesdroppers then began courtship themselves.
Previously, this kind of courtship behavior was seen in vertebrate animals. The discovery has changed the way animal biologists think about this little spider, says Alma College Biologist David Clark.
“Wolf spiders are displaying more sophisticated behavior than we thought they were,” says Clark. “Their brains are literally the size of a pinhead, but they are eavesdropping, signal matching and processing information to attract female spiders.”
The reactions of the field-collected spiders were surprising, says Clark.
“Spiders are supposed to be genetically pre-programmed, so you would think that where they were raised wouldn’t matter,” he says. “We found that the field-collected spiders behaved as if their ‘rival’ was courting a female nearby, though.”
Research into animal behavior can provide insights into how human physiology or neurobiology works, says co-investigator George Uetz, a University of Cincinnati professor of biological sciences, although spiders navigate a completely different sensory world from humans.
“There’s a lot of eavesdropping that occurs in the natural world, but it’s usually associated with more highly social animals with much bigger brains,” says Uetz. “It’s very common in birds, fish and mammals, but infrequently seen among invertebrates.”
Meanwhile, as the male spiders perform their mating dance, the female is sizing them up to consider whether they’re worthy mating material. If they don’t pass inspection, she’ll try to eat her suitor. About 12 percent of the males that successfully mate still get eaten, says Clark.
“Courting in response to other males’ signals is not without risks to the eavesdroppers,” says Clark. “The conspicuous courtship signals intended for females may also make males more visible to predators, like toads or birds searching for their next meal.”
The research, which also involved Alma College undergraduate students Corinna Kizer Zeef, Gabriel Sabovodny and Aaron Hollenberg, was conducted in the field in Cincinnati and in the labs at Alma College and the University of Cincinnati, with spiders collected from the Cincinnati Nature Center.
The journal, Animal Behaviour, is the flagship journal of the Animal Behavior Society and is a leading international publication containing research articles, critical reviews and original papers on all aspects of animal behavior.
University of Cincinnati Communications contributed to this report.