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Sexual cannibalism in the shing spider and a model for the evolution of sexual cannibalism
 

Summary: Sexual cannibalism in the «shing spider and a
model for the evolution of sexual cannibalism
based on genetic constraints
GO╚ RAN ARNQVIST* and STEFAN HENRIKSSON
Department of Animal Ecology, University of Umea╩, S-901 87 Umea╩, Sweden
Summary
Several hypotheses have been proposed for the evolution of sexual cannibalism by females. Newman and
Elgar (1991) suggested that sexual cannibalism prior to mating by virgin female spiders may have evolved as a
result of female foraging considerations. According to this model, an adult female's decision to mate or
cannibalize a courting male should be based on an assessment of the male's value as a meal versus his value as
a mate. The current study provides an empirical test of the assumptions and predictions of this model in the
sexually cannibalistic «shing spider. Adult females were subjected to dierent food treatments, and exposed to
adult males in the laboratory. However, only one of the assumptions of the model and none of its «ve
predictions were upheld. We failed to «nd any eects of female foraging, female mating status, female size,
male size or time of the season on females' behaviour towards courting males. Females behaved stereotypi-
cally, and many females were left unmated despite numerous mating opportunities. We also demonstrate costs
of sexual cannibalism in a natural population. We propose that the act of sexual cannibalism in the «shing
spider is non-adaptive, and develop a model for the evolution of premating sexual cannibalism in spiders
based on genetic constraints. According to this hypothesis, sexual cannibalism by adult females may have
evolved as an indirect result of selection for high and non-discriminate aggression during previous ontogenetic

  

Source: Arnqvist, G÷ran - Department of Animal Ecology, Uppsala Universitet

 

Collections: Environmental Sciences and Ecology