Sexual Cannibalism and Mate Choice Decisions in Wolf Spiders: Influence of Male Size and Secondary Sexual Characters.

ABSTRACT: The elaboration of male ornaments via sexual selection often increases until counteracted by other natural selection. However, sexual cannibalism may also influence expression of elaborate male traits, either by reinforcement or opposing selection pressure. Male Schizocosa ocreata (Hentz) wolf spiders (Lycosidae) have tufts of bristles on the first pair of legs used in signaling. We found that for males encountering virgin females, cannibalism risk varied with relative male and female size as well as female body condition, but not tuft size. Smaller males were more likely to be cannibalized by larger females. Males with larger tufts (relative to body size) are more likely to mate, but no other factors were associated with mating success. Post-mating cannibalism risk was associated with female size and age, male size, male body condition and male tuft size. Larger, older females were more likely to cannibalize smaller, poorer condition males with relatively smaller tufts. For males paired with previously mated females, probability of cannibalism was influenced by female and male size, as well as male tuft size. Larger females were more likely to cannibalize smaller males with relatively smaller tufts. None of the morphological characteristics of males or females influenced the second mating; the probability of a second mating was influenced by female age. Recently-matured females were more likely to mate a second time. Results suggest that mate choice and sexual cannibalism may impose reinforcing directional selection on male secondary sexual characters, depending on the shifting value of the male as a mate or meal.