The influence of environmental variance on the evolution of signalling behavior

A recent meta-analysis has indicated that environmental quality and variability can influence whether offspring begging and parental responses to these signals are motivated by offspring need or offspring quality. We create a model to verify and apply evolutionary logic to this hypothesis. We determine the ecological and social conditions under which species signal and respond to need in favorable environments, and to quality in poor environments. The environmental conditions that favor this shift are widest when signalling costs and differences in quality between offspring are moderate. Low relatedness between siblings coupled with high signalling costs, as well as moderate relatedness between siblings coupled with low signalling costs, allow for the shift between signals of need and signals of quality to occur in more volatile environments. Further, only species whose offspring are highly dependent on parents for survival are not expected to use both signals of need and of quality. Ul...