STUDIES INTO ABSTRACT PROPERTIES OF INDIVIDUALS - I - EMERGENCE IN GRASS INFLORESCENCES

We use emergence, the inability to predict the properties of higher hi erarchical levels from the properties of lower, as a means of explorin g some abstract properties of individuals. Biological hierarchies are often of increasing size of parts, from molecules to an organism. Emer gence in an individual also occurs in a hierarchy of different sized a ggregations of homologues-for example, spikelets in a grass infloresce nce. The evidence for emergence was differences among angles with a ve ctor of isometry as detected after bootstrapping. Emergence results fr om developmental variation and historical constraint. The former precl udes complete characterization, whereas the latter determines the degr ee of emergence through rendering certain variants nonviable. Developm ental variation arises from the continually changing external and inte rnal environments, the former arising from environmental fluctuations and heterogeneity, and the latter from the appearance of new parts; th e mechanisms leading to historical constraint are all those whereby an organism remains viable. Emergence is one aspect of the increasing co mplexity that occurs with development and may be related to the irreve rsible changes resulting from the dissipation of information into stru cture.