SEXUAL SELECTION IN FLOUR BEETLES - THE RELATIONSHIP BETWEEN SPERM PRECEDENCE AND MALE OLFACTORY ATTRACTIVENESS

Sperm precedence, defined as nonrandom differential fertilization succ ess among mating males, is an important postmating component of sexual selection. This study examined the relationship between premating and postmating components of sexual selection in males of the flour beetl e (Tribolium castaneum). Male olfactory attractiveness to females was positively correlated with a male's subsequent fertilization success: more attractive males achieved higher second-male sperm precedence whe n allowed to mate with previously inseminated females. Attractive male s may achieve compounded gains in their reproductive success through e nhanced mating opportunities as well as through greater fertilization success. Thus, the relationship between these reproductive fitness com ponents may augment differences in reproductive success among males. F emale fecundity, estimated as the number of adult progeny produced, in creased significantly with multiple matings. This result supports incr eased female reproductive success as a direct benefit of multiple mati ng in T. castaneum and suggests that progeny production is partially l imited by sperm availability. Total progeny production by doubly mated females remained constant at all levels of second-male sperm preceden ce. However, higher sperm precedence was associated with a decline in first-male progeny and a concomitant increase in second-male progeny. This pattern of progeny production suggests that more attractive males may achieve higher fertilization success through a combination of dis placement of previously stored sperm, transfer of greater sperm quanti ties, or females' preferential use of sperm of attractive males for fe rtilizations.