ARE THERE GENERAL-PRINCIPLES OF SIGNAL-DESIGN

Explanations of signal design must meet three requirements: they must be logically coherent, they must explain the diversity in size of anim al signals and they must explain the diversity in form of signals. Thr ee selection pressures operating on animal signals are discussed: the degree of conflict or cooperation, the 'efficacy' of signals and how s ignalling costs are paid. A distinction is made between cases where co sts of signalling are paid in the production of the signal and cases w here costs are paid as a consequence of giving a signal on the grounds that differences in signal design result. This is illustrated by refe rence to the example of warning coloration. It is concluded that gener al principles still elude us because of the numbers of different selec tion pressures that operate on the design of animal signals.