ABSTRACT
The Index of Biological Integrity (IBI) has been a useful method for evaluating environmental quality of aquatic habitats through the examination of stream fish communities. This chapter examines the role of history in determining fish distributions and diversity patterns. It discusses the patterns of population dynamics and biogeographic patterns relevant to fish distributions and local compositions, and hence, IBI criteria. Emphasis is placed on the importance of the interpenetration of local and regional processes within a historical framework, and that the key to understanding the basis for biodiversity lies in its history. An alternative way in which to examine community structure is through the historical biogeography of individual species. Stream capture is the major source of fish dispersal across drainage divides. Aquatic communities are assemblages of species united by regional history. This is apparent in both regional historical ecology and comparative historical biogeography of individual fishes.
