2.1 To eat or to mate? sexual cannibalism in mantodea and arachnid

Author: Rachel Carlson

Introduction

Mating interactions are frequently marked by conflict. Males and females have asymmetric goals in optimizing reproductive fitness, but they must rely on each other to produce offspring in sexual species ( [link] ). A dramatic example of intersexual conflict is sexual cannibalism, in which the female consumes the courting male before, during, or immediately after copulation (Buskirk et al. 1984). The male appears to be victimized, a hapless casualty of the female’s selfish drive to increase her nutrient store. However, examination of sexual cannibalism in the context of spider and mantis species reveals that these sexual selection pressures are accompanied by a host of costs and benefits to females as well as males

Intersexual conflict with respect to paternal investment

Intersexual conflict occurs when individuals in a mating interaction jockey for the greatest reproductive benefit at the lowest cost. Though individuals must cooperate at least during the mating act to produce viable offspring, their investment in the common young is often highly asymmetrical (Schneider and Lubin 1998). This fact is founded on the anisogamy of the sexes. Female eggs are significantly more nutrient-rich and exacting to produce than male sperm. The female also has fewer eggs than males do sperm. Since the donation of an egg is costlier than that of a sperm, females are immediately more committed to the offspring produced than males. Embryonic food demand places restrictions on the amount of offspring a female can produce in her lifetime, while male reproductive potential has a very high internal upper limit (Schneider and Lubin 1998). There are some rare species (sea horses, jacanas, for example) where males care more for progeny than females, reversing these strategies.