ABSTRACT

Before summarizing some of the available evidence about community “xity” through evolutionary time, below, it might be good to say a few words about how to dene a community. Boucot (1981, pp. 177-181) commented on the variety of ways to dene a community. Boucot’s view is that a community can most usefully be dened as a group of co-occurring organisms in which the varied taxa have abundances ranging from the very abundant to the rare, with the caveat that these abundances will vary within reasonable limits; one cannot dene communities by using taxic abundances taken to the nearest decimal point.