Aggregation Induced by Diffusing and Nondiffusing Media

Abstract

Gathering of individuals is a widespread phenomenon in biology. The reasons are, for instance, to give each other shelter, to reproduce, to explore new regions, to feed or to endure starvation conditions. In the case of myxobacteria (Dworkin & Kaiser 1993) it is known that they glide cooperatively and aggregate under starvation conditions. During gliding they prefer to use paths which were laid down by themselves. When the final aggregation takes place, they glide in streams towards developing mounds which later grow to form so-called fruiting bodies. Other examples of collective aggregation are known from larvae, e.g. of the bark beetle Dendroctonus micans (Deneubourg et al. 1990) which clumps to feeding groups. Group feeding often improves individual survival, or allows better exploitation of food resources (Tsubaki 1981, Tsubaki & Shiotsu 1982).