SIGNAL CONFLICT IN SPIDER WEBS DRIVEN BY PREDATORS AND PREY

Variation in the sensory physiologies of organisms can bias the recept ions of signals, driving the direction of signal evolution. Sensory dr ive in the evolution of signals may be particularly important for orga nisms that confront trade-offs in signal design between the need for c onspicuousness to allow effective transfer of information and the need for crypsis of the signal to unintended receivers. Several genera of orb-weaving spiders include conspicuous silk designs, stabilimenta, in the centre of their webs. Stabilimenta can be highly visible signals to predators, warning them of the presence of a noxious, sticky silk w eb. However, stabilimenta can also be used by prey as a signal in avoi dance of webs, creating a trade-off in signal visibility. I argue that the derived spectral properties of stabilimentum silk have resulted i n part from this conflict. The innate colour preferences of insects, t heir ability to learn colours, and the spectral properties of flowers all suggest that the reflectance spectra of stabilimenta renders them relatively cryptic to many insect prey, while maintaining their visibi lity to vertebrate predators.