Regional Patterns in Species Diversity

Local biological diversity is the outcome of regional species richness interacting with the local environmental conditions and ecological processes that govern the subset of species at a location. Later in this chapter we will explore in depth several hypotheses that attempt to explain local diversity, but we begin with patterns in regional diversity and the factors that operate at the largest spatial scales, because these determine the species pool from which local communities are assembled. As an example of the relevance of this perspective, variation in regional diversity was the single most consistent predictor of local fish diversity across some 320 sites from 61 streams distributed throughout the State of Virginia (Angermeier and Winston 1998). Variation in regional species richness itself is difficult to fully explain, but speciation, differences in the ability of individual species to disperse, and historical dispersal opportunities clearly influence the regional species pool, and these in turn are influenced by overall productivity, habitat diversity, and biological interactions (Rosenzweig 1995). Here, we review patterns in large-scale species richness that are likely to influence the regional species pool and thus indirectly affect local assemblages.

0 0

Post a comment