A general framework for the distance–decay of similarity in ecological communities

Abstract

Species spatial turnover, or b-diversity, induces a decay of community similarity with geographic distance known as the distance-decay relationship. Although this relationship is central to biodiversity and biogeography, its theoretical underpinnings remain poorly understood. Here, we develop a general framework to describe how the distance-decay relationship is influenced by population aggregation and the landscape-scale speciesabundance distribution. We utilize this general framework and data from three tropical forests to show that rare species have a weak influence on distance-decay curves, and that overall similarity and rates of decay are primarily influenced by species abundances and population aggregation respectively. We illustrate the utility of the framework by deriving an exact analytical expression of the distance-decay relationship when population aggregation is characterized by the Poisson Cluster Process. Our study provides a foundation for understanding the distance-decay relationship, and for predicting and testing patterns of beta-diversity under competing theories in ecology.

Turnover of soil bacterial diversity driven by wide-scale environmental heterogeneity

“…Indeed, DNA fingerprints correspond to dominant bands, each including multiple species. This results in an aggregation of species composition variations within the bands and may contribute to the low turnover rate observed 4 . In addition, DNA fingerprinting precludes consideration of the accumulation of new minor species ARTICLE with increasing distance, which may represent a large proportion of the total soil microbial species richness 33 and determine the slope of TAR 14,31 .…”

“…Morlon et al 4 demonstrated the relevance of distance-decay relationships for testing spatial ecology theories. We therefore compared three metrics relating bacterial community and habitat, namely turnover rates, initial and average similarities, to identify the processes involved in the spatial distribution of soil bacterial communities.…”

“…One way to tackle the spatial processing of microbial diversification is to evaluate the empirical relationship between geographical distance and genetic similarity of microbial assembly 4,5 , also known as the distance-decay relationship or the taxa-area relationship (TAR) 6 . Application of the TAR has demonstrated that the species richness of eukaryotic macroorganisms increases with the sampling area 7 .…”

“…Nowadays, TAR is commonly used in this form in most microbial biogeographical studies 3,9,[14][15][16] to assess microbial diversification and its potential relative dependency on ''dispersal'' and ''habitat heterogeneity'' (including habitat diversity and landscape configuration) 4 . Nevertheless, the TAR is still highly debated, particularly regarding its form, underlying hypotheses and factors affecting the relationship [17][18][19] .…”

“…Variations in microbial community between soils were assessed by bacterial Automated Ribosomal RNA Intergenic Spacer Analysis (ARISA) directly on soil DNA 25 . The TAR was then applied to ARISA data by considering the slope (z bacteria ) together with the initial similarity 5 (w 16 ) at the grain size of the study (16 km) and the average similarity ðwÞ as proposed by Morlon et al 4 to complete the analysis of community spatial variations. In parallel, soil habitat, namely the ''description of a physical place, at a particular scale of space and time, where an organism either actually or potentially lives'' 26 , was characterized by including pedoclimatic, geomorphologic and land-use data.…”