CannibalismBiology 342 Fall 06 |
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Sexual Cannibalism"The reproductive interests of males and females rarely coincide" (Schneider and Lubin 1996). |
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Sexual cannibalism, the killing and consuming of potential or actual mating
partners (Schneider and Lubin 1996), is a dramatic behavior that begs an explanation.
How can an action that results in the death of a conspecific and
potential mate be evolutionarily favorable? In the case of pre-copulation cannibalism, how can traits that allow an animal to be eaten before it can reproduce persist over evolutionary time? While sexual cannibalism is relatively uncommon compared to other types of cannibalism, it is occurs in a wide spread of invertebrates, from gastropods to many species of arachnids. Sexual cannibalism has been observed during courtship, during copulation, and shortly after copulation (Elgar and Crespi 128). |
Redback Spiders
Male redback spiders take sexual cannibalism to the extreme,
essentially committing suicide to feed themselves to their mates.
During copulation, males somersault themselves onto the fangs of the
female, and remain in this position until they are eaten, which depends
on the hunger level of the female. Males benefit from this sacrificial
behavior because males who are consumed mate longer, which leads to
increased paternity. Cannibalism of one male also decreases the chances
that the female will remate. Considering that males are unlikely to
mate again even if they survive one mating experience, the paternity
advantages of cannibalism overshadow the costs of suicide (Andrade 1996).
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