Arancibia, P. A. | bioRxiv Science

bioRxiv2026

Network topology differentially shapes ecological processes across scales in experimental metacommunities

The spatial configuration of habitat patches is a key driver of metacommunity dynamics, yet the role of network topology remains poorly understood. In this study, I experimentally tested how different aspects of network structure influence metacommunity processes operating at different spatial scales. Using protist microcosms, I assembled metacommunities with patches connected as random or scale-free networks, and quantified occupancy, biomass, and extinction dynamics in relation to local (patch degree) and global (closeness centrality) metrics of connectivity. Scale-free metacommunities supported higher occupancy and biomass than random networks. At local scales, biomass declined with increasing patch degree, suggesting that reduced connectivity may enhance productivity, likely by limiting negative interactions. In contrast, extinction dynamics were not related to degree but strongly associated with patch centrality, with network topology modulating the relationship. These results reveal a decoupling between ecological processes, showing that different components of network structure can regulate dynamics at different spatial scales.

ecology↗

bioRxiv2025

Experimental community ecology in decline: A call to embrace technology

Community dynamics are complex and thus challenging to infer from observational data alone. Experiments, with their ability to control variables and isolate mechanisms, are a powerful tool for uncovering the causal processes that drive community dynamics. They therefore allow us to move beyond correlations and to directly test theoretical predictions. Yet, because experiments are often logistically demanding and resource-intensive, they are less frequently employed than observational approaches in community ecology. Here, we trace the past three decades of experimental research in community ecology through a systematic literature review. We focus on the motivation behind experiments, their links to ecological theory, the types of questions they address, their scale, and the methods used to do this. Our results corroborate the historically tight relationship between experiments and ecological theory and document a gradual increase in experimental complexity --particularly related to the use of molecular methods. However, persistent gaps remain in the taxa and ecosystems studied, with aquatic ecosystems, fungi, and microbes still underrepresented compared to terrestrial plants and animals. Moreover, experiments are still limited in their spatial and temporal scale; they are typically short-term, local, and reliant on manual methods. The integration of high-throughput technologies with experimental workflows is still in its infancy, even though they are increasingly common in biomonitoring. To illustrate the potential of such tools in experimental research, we present a proof-of-concept study. It shows how automated technologies can be incorporated at different stages of the experimental workflow to expand the scale of experiments while reducing the reliance on human labor and potentially lowering financial costs. We conclude that many of the long-lasting biases and challenges in experimental community ecology could be addressed by combining technological innovations with broader collaboration among research groups. Coordinated networks, standardized protocols, and the integration of long-term and large-scale experimental designs can substantially improve in situ replication as well as cross-site comparability. Such efforts are essential for developing a more comprehensive mechanistic understanding of community dynamics across diverse ecosystems.

ecology↗