This website is the creation of a group (identified as Group 6) of University of Arizona Honors Biology students. It's basis is derived from the research of Dr. Jutta M. Schneider and Dr. Mark A. Elgar, and their paper: "Sexual cannibalism and sperm competition in the golden orb-web spider Nephila plumipes (Araneoidea): female and male perspectives" (Behavioral Ecology 12 (5) 547-552, 2001). The topic of the paper, and consequently this website, can be attributed to their faculty mentor, Dr. Robert L. Smith of the University of Arizona Department of Entomology.









  • Sexual cannibalism and sperm competition are two of many types of sexual conflict. Such conflicts are not necessarily beneficial to both sexes. Although multiple matings increase the reproductive success of males, it often causes sperm competition which ultimately reduces the reproductive success of the male. Sexual cannibalism may occur before or after copulation. In this particular case, biologists were interested in the adaptive value of cannibalism occurring after copulation in the Nephila plumipes spider.

  • Previous experiments on other spider species found that cannibalized males had a greater fertilization rate than noncannibalized males. Schneider and Elgar sought to identify the adaptive benefits of sexual cannibalization as they relate to both males and females. They theorized that cannibalization provides needed nutrients to a female, which in turn will increase her reproductive success. Thus, females in poorer condition should cannibalize their mates more frequently.

  • Although cannibalization denies a male of any further reproduction, it may increase their paternity in that particular female and thus ultimately will be beneficial. Furthermore, if females gain nutrition from their cannibalized mates then larger males should be cannibalized more often. Schneider and Elgar also looked for a correlation between cannibalism, copulation duration and paternity to confirm that sexual cannibalism allows a female control over the paternity of her offspring.

  • Ultimately, this experiment searched to find the adaptive value of sexual cannibalism in Nephila plumipes , which was expected to conform to the above expectations.