Analysis of positional information applied to cirral patterns of the ciliate Euplotes

Abstract

IN studying the relative positions of structural features on the surfaces of organisms, most biologists are content with qualitative impressions of pattern. This approach is inadequate when there are large variations among individuals, as occurs in the taxonomically important positional patterns formed by the locomotory organelles, the cirri, of the hypotrich ciliate genus Euplotes. The frequency distribution of all intercirral distances provides a quantitative measure of cirral pattern that incorporates individual variations. A comparative study¹ among different Euplotes populations of such distributions reveals a small set of basic cirral patterns. It also demonstrates that certain cirral patterns may be simulated by morphogenetically plausible alterations in others, thus supporting the hypothesis that certain cirral patterns are derivative of others. The theoretical creation of artificial positional patterns that mimic naturally occurring patterns provides a useful perspective on the systematics of this group of organisms.