Elgar, A.M., J.M. Schneider, and M.E. Herberstein. 2000. Female control of paternity in the sexually cannibalistic spider Argiope keyserlingi symbiosis. Proceedings of the Royal Society of London. Series B. 267:2439-2443.
Argiope keyserlingi is a remarkable orb-weaving spider that is famous for its sexually cannibalistic behavior. What selective pressures drive the female Argiope keyserlingi to wrap the disoriented male in webbing immediately after copulation and proceed to devour him? Is sexual cannibalism: a) the female's attempt to control the paternity of the offspring, b) a male or female strategy to increase female fecundity, or c) the male's strategy to increase his paternity?
In theory, males are under stronger selection pressures to control fertilization; however, it has been demonstrated that females may have the capacity to control sperm competition among mating males by controlling the duration of copulation.
Elgar et al. randomly exposed each female to two males simultaneously or successively. The length of copulation was measured from when the male inserted his pedipalp to when the female ceased mating. Elgar et al. observed that the size difference between the two males the female was exposed to significantly affected the length of time that she would mate with them. Smaller males mated for longer than the larger males, but they were also cannibalized more than the larger males. Sexual cannibalism did not affect the fecundity of the female, nor did it appear to be a male strategy for increasing paternity.
Elgar et al. concluded that the female controls the paternity of the offspring by delaying the cannibalization of her second mate if he is significantly smaller than the first, thus, allowing him to fertilize a larger proportion of her eggs.
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