Taxonomic and sensory biases in the mate-choice literature: there are far too few studies of chemical and multimodal communication

The sexual selection literature has grown rapidly in recent years. In an effort to elucidate biases in the focus of current mate-choice research here, I review 297 studies among 230 species. Among taxa, studies of birds were most common (40% of all studies), with insects, fishes, and anurans less well represented (20%, 18%, 14%, respectively). All other taxa were poorly represented in the literature (< 3%). Across sensory modalities, studies of visual and acoustic signals were most common (46%, 30%, respectively), with relatively few studies investigating chemical, tactile, and electrical signals in mate choice (3%, 3%, < 1%, respectively). Most mate-choice studies of birds and fishes investigated visual signals, while the majority of insect and anuran studies investigated acoustic signals. While these associations may reflect biological realities-birds and anurans tend not to emphasize chemical cues in mate choice; electric communication may indeed be quite uncommon-they may also be grossly misleading: chemical cues are likely critical for mate choice in millions of insect species. Moreover, I suggest that the particularly high vulnerability of chemical communication networks to anthropogenic fouling should provide immediate motivation for many more studies of chemical signals in mate choice. Finally, I find that despite widespread acceptance that male displays are often comprised of multiple elements produced across sensory modalities, studies simultaneously investigating the use of multiple cues in mate choice are rare. While not exhaustive, this review identifies biases in the focus of mate-choice studies, and should serve to identify fruitful directions for future mate-choice research.