60 years of the equilibrium theory of insular biogeography: problems of testing, results of the field studies, applied importance

A review is presented of publications dealing with analysis of species richness of island biological communities and habitat islands based on the equilibrium theory of insular biogeography by MacArthur and Wilson (1963). Principal points of the theory are considered along with its shortcomings, problems and results of its testing. Also, possibilities are appraised for using recommendations elaborated on the base of the theory in nature conservation practice. The results of island and habitat island biota studies indicate that in many cases data corroborate the equilibrium theory while in many other cases they do not. In particular, for cenoses fragmented 50-250 years ago, especially for the ones formed by long living species, there have been no conspicuous effects of species relaxation detected. At that, the theory prediction of substantial reduction in species richness of fragmented communities in the long run is hardly disputed. The results of studies conducted in the field of insular biogeography are taken as a basis for recommendations on the long-term conservation of isolated communities integrity, although mostly they are of qualitative nature.