Metacommunity detectives: Confronting models based on niche and stochastic assembly scenarios with empirical data from a tropical stream network

Abstract

Metacommunity models predict that species richness and composition patterns in communities are determined predominantly by environmental selection and dispersal, with speciation and drift playing a lesser role. In the tropics, our understanding about these processes comes almost purely from empirical data; there is lack of formal confrontation between models and data. Here, we evaluated if a metacommunity simulation model designed for riverine networks could predict insect diversity patterns observed in a tropical stream network within the Atlantic Forest biome. Our individual‐oriented model simulated biological processes, including dispersal of adults, oviposition, dispersal of larvae, colonisation and mortality. We used this model to simulate communities considering three assembly scenarios (niche, niche–stochastic and stochastic) and three flight dispersal ability groups (low, medium and high). To parameterise the model, we used data from 97 riffle communities, distributed along a stream network, and biological data from the literature. For the high dispersal ability group, none of the assembly scenarios significantly predicted the observed richness and community dissimilarity. The niche–stochastic assembly scenario, however, provided a better approximation of observed richness and community dissimilarity for the medium and low dispersal ability groups. Our results show that deterministic and stochastic processes combine to better explain observed aquatic insect diversity patterns. Although simulations were limited to similar explanatory power to studies using pattern‐oriented approaches, our findings highlight the promise of a more predictive use of metacommunity simulation models.

Community size affects the signals of ecological drift and niche selection on biodiversity

“…The role of stochastic community assembly processes in arranging species within and among communities has gained support from models (Mouquet and Loreau 2003, Orrock and Fletcher 2005, Durães et al 2016) and data (Cottenie 2005, Lancaster and Downes 2017, Germain et al 2017, Swan and Brown 2017, Valente-Neto et al 2017. Here, we provide empirical evidence that community size, a simple characteristic of communities, may mediate the interplay between niche selection and ecological drift as drivers of β-diversity in tropical and boreal metacommunities.…”

Colonisation, emigration and equilibrium of stream invertebrates in patchy habitats

“…Understanding the links between ecosystem functioning, species’ traits and the mechanisms that determine species diversity gradients requires description of ecological processes at small scales (Baird et al., ; Willig, Kaufman, & Stevens, ). In streams, local biotic diversity is influenced by many factors, including both niche and neutral processes (Brown, Wahl, & Swan, ; Thompson & Townsend, ; Valente‐Neto, Durães, Siqueira, & Roque, ) such as habitat characteristics, species’ traits and interactions, disturbance and dispersal (Astorga, Heino, Luoto, & Muotka, ; Pearson et al., ; Rosser & Pearson, ). An ecological issue that is unresolved generally is the nature of the link between diversity and productivity (Grace et al., ; Gross, ; Pierce, ), which, in streams, is frequently enhanced by anthropogenic nutrient inputs that alter biotic assemblages (Connolly & Pearson, ; Dudgeon et al., ; Malmqvist & Rundle, ).…”

Metacommunities in river networks: The importance of network structure and connectivity on patterns and processes

“…The eleven papers in this issue span a variety of approaches, including field (Brown, Wahl, & Swan, ) and laboratory experiments (Altermatt & Fronhofer, ), modelling (Anderson, Hayes, & Sarhad, ; Carraro, Mari, Gatto, Rinaldo, & Bertuzzo, ; Helton, Hall, & Bertuzzo, ; Valente‐Neto, Duraes, Siqueira, & Roque, ), species distribution models (de Mendoza et al., ), population genetics (Prunier, Dubut, Loot, Tudesque, & Blanchet, ) and conceptual synthesis (Tonkin et al., ). These studies cover a wide range of topics and focal organisms, including disease spread (Carraro et al., ), nutrient uptake (Helton et al., ), trophic dynamics (Anderson et al., ), effects of anthropogenic stressors (Prunier et al., ), and the joint roles of dispersal and environmental filtering in structuring taxonomic groups ranging from diatoms to fishes (Brown et al., ; de Mendoza et al., ; Jamoneau, Passy, Soininen, Leboucher, & Tison‐Roseberry, ; Schmera et al., ).…”

“…These studies cover a wide range of topics and focal organisms, including disease spread (Carraro et al., ), nutrient uptake (Helton et al., ), trophic dynamics (Anderson et al., ), effects of anthropogenic stressors (Prunier et al., ), and the joint roles of dispersal and environmental filtering in structuring taxonomic groups ranging from diatoms to fishes (Brown et al., ; de Mendoza et al., ; Jamoneau, Passy, Soininen, Leboucher, & Tison‐Roseberry, ; Schmera et al., ). Finally, the papers cover a broad geographic gradient from the Neotropics of Brazil (Valente‐Neto et al., ) to subarctic Finland (de Mendoza et al., ), thereby avoiding the typical bias to temperate riverine systems only. A common theme among these studies is that the structure of the network and spatial dynamics do indeed regulate dynamics of populations and communities, and their associated functions.…”

“…Valente‐Neto et al. () used a metacommunity simulation model developed for river networks to predict empirical stream insect diversity in a Brazilian stream network. Their model was parameterised by an aquatic insect species pool, based on empirical data, as well as an environmental gradient and river network structure.…”