Data from: Sexual signals for the colour-blind: cryptic female mantids signal quality through brightness

1. Cryptic coloration may evolve in response to selective pressure imposed
by predators, yet effective intraspecific communication may require some
level of detectability. This creates a tension between the benefits of
sexually selected visual traits and the predatory costs imposed by greater
conspicuousness, and little is known about how this tension may be
ameliorated in highly cryptic species. 2. We explore these competing
demands in the false garden mantid Pseudomantis albofimbriata, a
colour-blind and seemingly cryptic insect. We use reflectance spectrometry
and receptor-noise modelling to characterize the conspicuousness of mantid
body regions in the visual systems of mates (mantids), as well as
potential predators (birds) and prey (bees). We then use condition
manipulation and conspecific choice tests to further explore the colour
traits of interest. 3. Based on visual modelling, we find that male
mantids are inconspicuous to conspecifics, prey and predators – that is,
they are chromatically and achromatically cryptic. In contrast, female
mantids are chromatically cryptic to all potential receivers, but their
abdomens are achromatically conspicuous. Our food manipulation experiment
shows that females in good condition (and therefore with more eggs) have
brighter abdomens than females in poor condition. Choice assays show male
mantids are consistently attracted to females bearing brighter abdomens.
4. Our results reveal brightness-mediated sexual signalling in a
colour-blind and classically cryptic insect. By communicating in the only
visual channel available to them, female mantids are conspicuously
signalling their quality to mates, while potentially minimizing their
conspicuousness to predators and prey. Furthermore, by signalling with
only a single body region, female mantids are apparently using coincident
disruptive coloration to further decrease detectability to potential
eavesdroppers. 5. Our data reveal a novel example of the way in which the
trade-off between sexual selection for conspicuousness and natural
selection for crypsis may be mediated in a visual signalling system. Such
signals may be common in apparently cryptic species, and this study once
again demonstrates the importance of analysing visual signals beyond the
capacity of human vision.