General patterns of taxonomic and biomass partitioning in extant and fossil plant communities

Abstract

A central goal of evolutionary ecology is to identify the general features maintaining the diversity of species assemblages. Understanding the taxonomic and ecological characteristics of ecological communities provides a means to develop and test theories about the processes that regulate species coexistence and diversity. Here, using data from woody plant communities from different biogeographic regions, continents and geologic time periods, we show that the number of higher taxa is a general power-function of species richness that is significantly different from randomized assemblages. In general, we find that local communities are characterized by fewer higher taxa than would be expected by chance. The degree of taxonomic diversity is influenced by modes of dispersal and potential biotic interactions. Further, changes in local diversity are accompanied by regular changes in the partitioning of community biomass between taxa that are also described by a power function. Our results indicate that local and regional processes have consistently regulated community diversity and biomass partitioning for millions of years.

Absence of phylogenetic signal in the niche structure of meadow plant communities

“…This hierarchical view of the evolution of ecological traits explains the frequent observation that species : genus ratios within communities are often higher than expected (Tofts & Silvertown 2000;Enquist et al 2002). Our results indicate that the reason for this is that habitat-determining b niches evolve relatively slowly, while a niches on which coexistence depends evolve much more rapidly.…”

Genus age, provincial area and the taxonomic structure of marine faunas

“…Enquist et al 2002;Krug et al 2008). Here we develop an alternative approach, fitting parametric models to the shapes of taxonomic diversity distributions (figure 1a).…”

Scaling and power-laws in ecological systems

“…In a later analysis of the same data set Enquist et al (2002) biomass (M tot ) per 0.1·ha plot] is invariant with respect to number of species (S) (i.e. M tot ϰS 0 ) implying that an increase in species richness within communities results in a finer division of biomass instead of an increase in total biomass.…”

“…Notice that this invariant, as well as the 'energetic equivalence rule', entail the existence of an ecological zero-sum dynamic (Van Valen, 1980) consistent with recent symmetric models of community assembly (Hubbell, 2001). However, it remains to be seen if the biomass invariant described by Enquist et al (2002) applies to taxa other than trees and how it changes when more than one trophic level is analyzed.…”