PROSPECTS FOR SEX-ROLE REVERSAL IN TELEOST FISHES

Teleost fishes, by virtue of their diverse reproductive modes, offer an opportunity to address general questions about the evolution of sex differences. A comparison of the reproductive rates of males and females within a species or population provides an empirical basis for predicting which sex will compete more intensely for access to mates and thus be subject to stronger sexual selection: it will be the sex with the higher maximum reproductive rate. In order to assess relative reproductive rates in teleost fishes, and to test this principle, four reproductive measures are needed for each species or population: (1) maximum female clutch size, (2) minimum female interclutch interval, (3) maximum male brood size (relative to clutch size), and (4) minimum interbrood interval for males (relative to interclutch interval). This reproductive rates approach should reveal more examples of sex role reversal in teleosts and could contribute to the development of hitherto largely unformulated generalisations about sex differences in teleost fishes.