Metacommunity‐scale biodiversity regulation and the self‐organised emergence of macroecological patterns

Abstract

There exist a number of key macroecological patterns whose ubiquity suggests that the spatio‐temporal structure of ecological communities is governed by some universal mechanisms. The nature of these mechanisms, however, remains poorly understood. Here, we probe spatio‐temporal patterns in species richness and community composition using a simple metacommunity assembly model. Despite making no a priori assumptions regarding biotic spatial structure or the distribution of biomass across species, model metacommunities self‐organise to reproduce well‐documented patterns including characteristic species abundance distributions, range size distributions and species area relations. Also in agreement with observations, species richness in our model attains an equilibrium despite continuous species turnover. Crucially, it is in the neighbourhood of the equilibrium that we observe the emergence of these key macroecological patterns. Biodiversity equilibria in models occur due to the onset of ecological structural instability, a population‐dynamical mechanism. This strongly suggests a causal link between local community processes and macroecological phenomena.

The concerted emergence of well-known spatial and temporal ecological patterns in an evolutionary food web model in space

“…O'Sullivan et al 18 found in a competitive metacommunity assembly models a similar collection of macroecological patterns (SAD, range size distribution RSD and SAR) as we did, when regional diversity was near equilibrium. They refer to the work of McGill 16 who analysed the assumptions underlying models of macroecological patterns and found that three key ingredients seem to be sufficient for such patterns to emerge.…”

“…Those are hollow curve SAD (implying that one empirical pattern is explicitly presupposed in order to obtain other patterns), clumping of populations in space, and a lack of spatial correlation of populations. Those features emerged in a simple assembly model near regional diversity equilibrium that also reproduced spatial ecological patterns, like SAR and range size distributions 18 . May and coauthors 19 showed that these three features are not sufficient to reproduce patterns in empirical data of tropical forests.…”

“…Especially for temporal patterns obtaining fossil food web data is nearly impossible, considering how much effort needs to be put into the reconstruction of a single food web from a single lagerstätte 24 . Models often dodge the challenge of incorporating food web structure by using competitive communities 18,25 or neutral models which are valid for only one trophic layer 26,27 .…”

Metacommunity theory for transmission of heritable symbionts within insect communities

“…Previous work on microbiomes has suggested that stochasticity plays a significant role in community assembly, and that the process is inherently hard to predict (see Adair, Wilson, Bost, & Douglas, 2018;Obadia et al, 2017;Sieber et al, 2019;Vega & Gore, 2017), based on findings that are consistent with the neutral theory of biodiversity (Hubbell, 2001). Recent models for metacommunity diversity (e.g., O'Sullivan, Knell, & Rossberg, 2019) can be utilized to answer questions about ecological structural stability influencing microbiome diversity, and whether the microbiome adheres to broad ecological patterns of diversity. For instance, testing whether symbiont communities fit the species-abundance distribution (SAD) or species-area relation (SAR).…”

Temporal β diversity—A macroecological perspective

“…One promising direction would be an extension of the MoB (measurement of biodiversity) approach (McGlinn et al, ) used to assess the relative contributions of the spatial arrangement of individuals, density, and the species abundance distribution, to trends in species richness. Another is the metapopulation approach developed by O’Sullivan et al () in which regional dynamics are modelled using Lotka–Volterra competition equations. This method makes no a priori assumptions about spatial structure and the distribution of abundance yet can reproduce ubiquitous patterns such as the species abundance distribution and species–area relationships.…”