Research: “Desperado” male spiders work harder to attract a mate

New research shows that less attractive male spider “desperados” work harder than their more attractive competition to get female attention, especially when there’s a predatory risk involved.

Two experiments examined the courtship behavior of male wolf spiders. The first looked at the relationship between attractiveness and courtship behavior (which, for these spiders, means raising and lowering the front legs, among other such behaviors). They measured the symmetry of the spiders’ front legs, symmetry indicating higher levels of attractiveness. 

The researchers were surprised to find in the first experiment that the less symmetrical spiders did fewer leg raises than the symmetrical ones. As a mating ritual, researchers posit that the leg raises serve to show off the symmetry (or lack thereof) of the spiders’ legs for the female spider. And the female spiders noticed: While not all of the spider pairs mated, all of those that did had symmetrical legs.  

The second experiment introduced signals that a predator was near. The more attractive males, believing that they had a good chance of finding a mate again in the future, did not court as aggressively when there was a threat present. This is an example of asset protection—the spiders upped their chances for survival in lieu of mating, explains Matt Persons, professor of biology at Susquehanna University in Selinsgrove, Pa. On the other hand, he says, the less attractive males did more leg raises, an example of the “desperado effect.” Realizing they will have a difficulty attracting mates in the future and perceiving risky conditions, they seize the moment and flaunt what they can, hoping to attract a mate. Increased courtship in lab conditions didn’t necessarily lead to better mating success. However, in the natural environment, this “desperado” behavior might pay off. 

The paper, "Cautious versus desperado males: predation risk affects courtship intensity but not female choice in a wolf spider,” was published online in the journal Behavioral Ecology on Dec. 31 and is forthcoming in print. It was co-authored by Ann L. Rypstra of Miami University and Sean E. Walker of California State University

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Susquehanna University
Professor of Biology
570-372-4526 (office)