Community Diversity: Relative Roles of Local and Regional Processes

Abstract

The species richness (diversity) of local plant and animal assemblages-biological communities-balances regional processes of species formation and geographic dispersal, which add species to communities, against processes of predation, competitive exclusion, adaptation, and stochastic variation, which may promote local extinction. During the past three decades, ecologists have sought to explain differences in local diversity by the influence of the physical environment on local interactions among species, interactions that are generally believed to limit the number of coexisting species. But diversity of the biological community often fails to converge under similar physical conditions, and local diversity bears a demonstrable dependence upon regional diversity. These observations suggest that regional and historical processes, as well as unique events and circumstances, profoundly influence local community structure. Ecologists must broaden their concepts of community processes and incorporate data from systematics, biogeography, and paleontology into analyses of ecological patterns and tests of community theory.

Molecular phylogeography reveals island colonization history and diversification of western Indian Ocean sunbirds (Nectarinia: Nectariniidae)

“…Archipelagos also provide the opportunity to trace the evolutionary history of multiple evolutionary lineages in the same geographical setting. This can provide ÔreplicatesÕ for the testing of evolutionary hypotheses, and improve our understanding of the relative contribution of local, regional, and historical processes, as well as unique events and circumstances, to community diversity (Arnold, 2000;Bermingham and Moritz, 1998;Juan et al, 2000;Ricklefs, 1987;Ricklefs and Bermingham, 2001).…”

Taxonomic groups with lower movement capacity may present higher beta diversity

“…Beta diversity, on the other hand, describes how the species composition varies in time and/or space between habitats/units (Whittaker, 1960(Whittaker, , 1972Koleff et al, 2003;Anderson et al, 2010). Gamma diversity is the entire species diversity observed in an area, landscape or region that contains a certain set of sampling units (Whittaker, 1960; Tuomisto, 2010).Beta diversity thus relates the alpha to the gamma diversity (Ricklefs, 1987;Anderson et al, 2010), indicating how many species are shared between the habitats/units and, therefore, the degree of biotic heterogeneity of a region (Wilson & Shmida, 1984). Beta diversity may be positively associated with environmental heterogeneity (Soininen et al, 2007a) or be independent from it, varying only with space (Hubbel, 2001).…”

“…Several factors contribute to the diversity structure in communities and such factors are usually scale-dependent and interact with ecological, evolutionary and biogeographical processes (Ricklefs, 1987;Pineda & Halffter, 2004;Gardner et al, 2009). Species diversity in an area can also be considered at diff erent scales, and can be split into alpha, beta and gamma components (Whittaker, 1960(Whittaker, , 1972.…”

“…Beta diversity thus relates the alpha to the gamma diversity (Ricklefs, 1987;Anderson et al, 2010), indicating how many species are shared between the habitats/units and, therefore, the degree of biotic heterogeneity of a region (Wilson & Shmida, 1984). Beta diversity may be positively associated with environmental heterogeneity (Soininen et al, 2007a) or be independent from it, varying only with space (Hubbel, 2001).…”

Species richness in natural and disturbed habitats: Asteraceae and Flower-head insects (Tephritidae: Diptera)

“…The estimation of local richness for studies of associated communities is essential to understand species richness patterns and their implications (Ricklefs 1987). Thus, studies of insect-plant systems in different locations with different land uses enable the evaluation of the relative importance of local and regional processes, providing the means to determine the best management practices and the rational land use.…”