Variation in sexual dimorphism in nonmarine Calanoid copepods and its ecological significance

Significant differences exist in the degree of sexual dimorphism in a series of closely related nonmarine calanoid copepods. Strongest dimorphism is found in species that occur exclusively in temporary waters. No species known only from permanent waters is strongly dimorphic except where it typically occurs as the sole calanoid in such waters. It is suggested that, in situations where interspecific competition is likely to be minimal, pronounced sexual dimorphism enhances efficiency of food exploitation by allowing the consumption of an exceptionally wide range of particle sizes.