Hover Fly Eyes and Antennae Are Sexually Dimorphic but Do Not Tradeoff.

Sensory systems are energetically expensive and may evolve through tradeoffs between modalities. We tested the sensory tradeoff hypothesis in four hover fly species by examining allometry and sexual dimorphism in eye and antennal (funiculus) size. Across species, larger flies exhibited larger sensory structures and males generally possessed relatively larger eyes and funiculi than females after controlling for body size. However, we found no consistent negative relationship between eye and antennal investment within species. These findings suggest that sensory investment in hover flies is shaped more strongly by allometric and sex-specific selection pressures than by compensatory tradeoffs between sensory modalities.