About Commensurability of Diversity within and among Communities

(1) Background: Is variation among the communities of a metacommunity higher than within communities? Community ecologists and population geneticists often characterize structure metacommunities by partitioning (diversity) into two following components using measures such as FST or GST α- β-diversity. The within-communities component is usually some average (type, species, genetic) diversities communities, among-communities additive multiplicative complement overall diversity. Such an lacks independent conceptual specification, matter long-standing dispute. Only if are independently commensurably specified can central question comparability be answered meaningfully. (2) Methods: A novel approach to overcoming this weakness identifies principles (concentration division) then relates these common notions distinguishes primary indicators quantify principles, transforms conceptually (indices) attains their commensurability thus comparability. application methods quantifying effects evolutionary mechanisms outlined. (3) Results: Common approaches corrected extended. (a) Analyses metacommunity/metapopulation structures that rely on apportionment related indices take its differentiation yield incomparable communities. (b) practice total diversity produces inconsistent ranking components. (c) concentration division result from elementary processes adaptive migration (gene flow) where (commensurable) amounts community reflect relative participation in structuring translate directly (d) modelling contributions restricted marginal distributions types affiliation. (e) model demonstrates degree which adaptational at level mixtures events