Negentropy and the evolution of chemical recruitment in ants (Hymenoptera: Formicidae)

Abstract

The applicability of the concept of negentropy to the study of evolution is tested by tracing the phylogeny of the information content of the communication systems used for recruitment in the Formicidae. Data from the literature is reviewed and ordered around theoretical evolutionary routes based on increasing negentropy of the chemical communication systems used. One pathway presupposes the development of chemical orientation prior to chemical attraction, i.e. signalling the presence of food; whereas the others begin with the chemical attraction of nestmates without orientation with chemical cues to the food. The results suggest that the Myrmicinae, Ponerinae, Dolichoderinae, Pseudomyrmycinae and possibly Dorylinae evolved chemical recruitment via chemical attraction, whereas the Formicinae evolved chemical recruitment via chemical orientation. These alternative patterns permit the establishment of phyletic trends based on glandular evolution for chemical recruitment. The results are compared with phylogenetic studies based on morphological and chemical characters, and it emerges that the recruitment behaviour proves to be a particularly conservative characteristic, in that it is evident in the same form in a wider range of species. The conclusion is reached that the negentropy content of living systems is a powerful tool in phylogenetic studies, even of small taxonomic groups.