An integrative framework of coexistence mechanisms in competitive metacommunities

Abstract

Species distribution in a metacommunity varies according to their traits, the distribution of environmental conditions and connectivity among localities. These ingredients contribute to coexistence across spatial scales via species sorting, patch dynamics, mass effects and neutral dynamics. These mechanisms however seldom act in isolation and the impact of landscape configuration on their relative importance remains poorly understood. We present a new model of metacommunity dynamics that simultaneously considers these four possible mechanisms over spatially explicit landscapes and propose a statistical approach to partition their contribution to species distribution. We find that landscape configuration can induce dispersal limitations that have negative consequences for local species richness. This result was more pronounced with neutral dynamics and mass effect than with species sorting or patch dynamics. We also find that the relative importance of the four mechanisms varies not only among landscape configurations, but also among species, with some species being mostly constrained by dispersal and/or drift and others by sorting. Changes in landscape properties might lead to a shift in coexistence mechanisms and, by extension, to a change in community composition. This confirms the importance of considering landscape properties for conservation and management. Our results illustrate the idea that ecological communities are the results of multiple mechanisms acting at the same time and complete our understanding of spatial processes in competitive metacommunities.

The Interplay Between Landscape Structure and Biotic Interactions

“…Until recently, empirical studies of metacommunites have not considered landscape structure explicitly [44,45]. Yet variation in dispersal rate among species in a metacommunity-a key component of metacommunity dynamics-can result from species' traits or structural aspects of the landscape (e.g., distance between patches, matrix structure, and arrangement of patches) [46].…”

“…Whereas metacommunity models include general variation in dispersal, few investigations (e.g., [47]) explore how dispersal is affected by both functional connectivity, i.e., the role of species traits and their interaction with the landscape, and structural connectivity, i.e., spatial configuration of landscape features [48]. As functional connectivity is a species-specific concept [49], considering it as such will likely better represent dispersal dynamics in metacommunities [45].…”

“…Metacommunity studies also show that competitive interactions can be affected by landscape structure [45]. In simulation studies of metacommunities, increasing the number of suitable and available habitat patches, landscape heterogeneity, and the size of a metacommunity can all enable more chances for colonization events and lead to greater community monopolization [54]-the ability of a species to arrive to a new patch, establish, and evolve to monopolize resources and strongly compete with any conspecific immigrant [55].…”

“…The set of theories described above link landscape ecology and community ecology, yet there are still important theoretical connections to be made. Advancing theory that integrates these subfields of ecology could be achieved via simulation modeling [45], meta-analyses (e.g., [63]), and landscape-scale experiments (e.g., [64]). …”

Neutral theory of biodiversity: Controversies and a transvaluation of species conservation

“…Porém, como o próprio Hubbell (2001) afirmou, ambas as teorias possuem sua aplicação em comunidades. Diversos experimentos de campo, experimentos laboratoriais com micro-organismos e testes de modelos demonstraram que as duas teorias atuam sobre comunidades de diferentes espécies e que ao longo do tempo tantos fatores estocásticos quanto direcionais oriundos da seleção natural e do nicho poderão agir com maior ou menor intensidade sobre a abundância das espécies (Gewin, 2006;Cadotte, 2007;Blundo et al, 2016;Fournier et al, 2017). Porém, é esperado que uma sínte-se unificadora demonstrando as diferentes influências da teoria neutra e de nicho sobre a estrutura de comunidades ao longo do tempo ainda demorará a ser plenamente usada (De Marco-Jr., 2006).…”