Male Nursery Web Spiders Mate More Successfully When They Offer Better Gifts
If you've ever felt that it is not just the thought that counts, you're not alone, according to a new study. Female spiders expect decent gifts, too.
Male nursery web spiders typically present females with silk-wrapped gifts before mating, but a new study out of Aarhus University in Denmark and Instituto de Investigaciones Biologicas Clemente Estable in Uruguay examined how the giving of the gift -- and the quality of what was offered -- affected their mating opportunities.
According to BioMed Central, researchers Maria. J Albo, Gudrun Winther, Cristina Tuni, Soren Toft and Trine Bilde provided male spiders with a variety of items with which to "woo" their mates, including houseflies (a treat to a nursery web spider), inedible cotton balls, a dry flower head, or empty exoskeletons of already-devoured bugs (the arachnid equivalent of offering your loved one a to-go box of gnawed on chicken bones). The identical size of the gifts (and the silk wrapping) meant that the female spider could not know the package's contents until she unwrapped it, according to researchers.
Researchers found that female spiders allowed males who had given them edible gifts to mate with them longer than those who provided inedible gifts (those that provided no gift at all were given the shortest amount of time to transfer their sperm before being rejected).
But it wasn't only the females who judged mates based on the gifts. Male nursery spiders fake death -- a practice known as thanatosis -- when a female attempts to end mating prematurely and run away with the gift. Male spiders "faked it" in half of the matings in which an edible gift was presented, but only one spider faked his own death when the female attempted to cut and run after receiving a "worthless" gift.
The spiders' reaction aren't that different from human behavior when it comes to sex and gifts, at least according to a study examining sex and advertising by Kathleen D. Vohs of the University of Minnesota. The study, published in February 2009 in The Journal of Consumer Research found that women respond more favorably to sex-based ads when the objects being sold were presented as a gift from a man to a woman to show his commitment, while men responded less favorably to sex-based ads that involved gifts. "Despite their steadfast support for sex-based advertising, we did find that men reacted negatively to sexually explicit ads when the ads strongly reminded men that they may, at times, devote monetary resources in pursuit of sexual contact," the authors told Live Science.
If you subscribe to the theory of sexual economics, then it makes sense for both female spiders and homo sapiens to call the shots when it comes to sex (and hold out for that token of affection before reproducing, be it a housefly or an actual house).