Species Diversity and Compensatory Phenomena in Communities and Biotic Systems

摘要

Diverse phenomena that can be interpreted as compensation of species diversity depletion are observed in communities and biotic systems. Compensatory phenomena are especially pronounced under extreme conditions that limit species diversity. The following different forms of compensatory mechanisms are discussed: an increase in the population density of individual species; niche expansion; an increase in intraspe-cific diversity and multidominance, i.e., the dominance of a certain species in a number of diverse communities, assemblages, and guilds; an increase in relative species richness proportion in regional or zonal fauna or flora in taxocenoses, communities, or local floras and faunas; intense microevolutionary processes, such as intraspe-cificadaptive radiation and explosive speciation so-called bundles of species; and channeled evolution, resulting in large-scale morphological and ecological differentiation, i.e., an increase in the range of differences between species within genericgroups, against the background of the taxonomic depletion of the biota. It is proposed that these phenomena could have provided for increased rates of evolution in ancient ecosystems and at early stages of phyletic group development.