Captivating color: evidence for optimal stimulus design in a polymorphic
prey lure
Abstract
Araneid spiders use abstract color patterns to attract prey. The
chromatic properties of these displays vary extensively, both within and
across species, and they are frequently polymorphic. Variation is often
expressed in terms of signal hue (color per se), but it is unclear
precisely how attractiveness scales with this property. We assessed
captures among color-manipulated females of the dimorphic jeweled spider
Gasteracantha fornicata in their natural webs. The manipulation
magnified the natural variation in stimulus hue independently of chroma
(saturation) across a range spanning most of the color spectrum. Catch
rate varied across treatments in simple accordance with how greatly
stimulus hue deviated from either of the two extant phenotypes.
Predictions based upon fly-perceived background contrast were
unsupported despite dipterans constituting ~60 % of
prey. This study isolates the importance of stimulus hue and supports
the premise that extant phenotypes reside in an optimal spectral range
for prey attraction.