Body Size and Differential Mating Success between Males of Two Populations of the Mediterranean Fruit Fly

Mate preference experiments were conducted between males from two populations of the Mediterranean fruit fly, Ceratitis capitata, to investigate the effect of body size on mating success. The results of the experi­ ment indicate that increased body size of males cannot be equated with mating success. In the lek behavior phase , physical encounters between males for pos­ session of a preferred territory seem to favor a male with a larger body size. However, males from one of the populations were twice as successful in mating with females of either population than males from the other population despite their significantly smaller body size. Thus, it appears that while size may possibly be correlated with intrasexual selection and the establishment of a dominance hierarchy within the lek, courtship performance is stll the most important criterion for mating success in the medfly. MATING, AS AN ESSENTIAL ACT in sexually re­ producing species, can be divided into two basic processes. The first process functions to bring the two sexes into close proximity, and the second process , courtship, leads to copula­ tion . For most animals that form only tem­ porary associations during mating and make little or no investment beyond that of provid­ ing gametes, both processes are essential com­ ponents of the mating system. The lek system is one such mating system in which both processes are essential compon­ ents. A lek is defined as an aggregation of territories used by males for the sole purpose of mating (Wilson 1975). A territory is a posi­ tion within a lek defended by a male for court­ ship and mating. The lek therefore provides a localized assembly of males to which females in search of a mate are attracted, and func­ tions as a means ofbringing the two sexes into close proximity. Furthermore, the males that