Adaptive resemblance: a unifying concept for mimicry and crypsis
Adaptive resemblance (AR) is a broad and inclusive concept which requires that only one condition be met: that members of a species of organism gain fitness due to a selective advantage imparted by a resemblance to some cue or signal in the organism's environment. Essential to the evolution and maintenance of AR is the dynamic and ongoing relationship among model, mimic and selective agent (SA) that provides a complex selective milieu within which evolves resemblance. Because specifics of a resemblance, including phenotypic traits being imitated, the nature of the model, and the function of the resemblance, are not relevant to the concept of AR, the diversity and abundance of such resemblances are limited only by the diversity and abundance of exploitable model-SA relationships. Defined as it is by a single mimic-related criterion, AR thus provides the basis for uniting under one conceptual umbrella diverse resemblances that range from cryptic to sematic, interspecific to intraspecific, organismal to molecular, and material to attributive or implied. The defining criterion excludes incidental resemblances which are contrastingly defined as those which are the result of coincidental phenotypic responses to functional requirements or to other selective influences. Some adaptive resemblances are attributable to more than one selective factor and thus may be categorized in more than one way (having aposematic and procryptic functions, for instance), while some others apparently are due to incidental resemblance as well as adaptive (such as thermoadaptive and procryptic functions).