BACTERIAL SPECIES AND EVOLUTION - THEORETICAL AND PRACTICAL PERSPECTIVES

discussion of the species problem in modern evolutionary biology serve s as the point of departure for an exploration of how the basic scienc e aspects of this problem relate to efforts to map bacterial diversity for practical pursuits-for prospecting among the bacteria for useful genes and gene-products, Out of a confusing array of species concepts, the Cohesion Species Concept seems the most appropriate and useful fo r analyzing bacterial diversity, Techniques of allozyme analysis and D NA fingerprinting can be used to put this concept into practice to map bacterial genetic diversity, though the concept requires minor modifi cation to encompass cases of complete asexuality. Examples from studie s of phenetically defined Bacillus species provide very partial maps o f genetic population structure, A major conclusion is that such maps f requently reveal deep genetic subdivision within the phenetically defi ned species; divisions that in some cases are clearly distinct genetic species. Knowledge of such subdivisions is bound to make prospecting within bacterial diversity more effective, Under the general concept o f genetic cohesion a hypothetical framework for thinking about the ful l range of species conditions that might exist among bacteria is devel oped and the consequences of each such model for species delineation, and species identification are discussed, Modes of bacterial evolution , and a theory of bacterial speciation with and without genetic recomb ination, are examined, The essay concludes with thoughts about prospec ts for very extensive mapping of bacterial diversity in the service of future efforts to find useful products, In this context, evolutionary biology becomes the handmaiden of important industrial activities, A few examples of past success in commercializing bacterial gene-product s from species of Bacillus and a few other bacteria are reviewed.