Weak dispersal and landscape size inevitably promote local biodiversity in heterogeneous metacommunities of competing species
7 affiliations
- 1Research Unit of Environmental and Evolutionary Biology, naXys, ILEE, University of Namur, Namur, Belgium.
- 2Department of Biology, McGill University, Montreal, Canada.
- 3Department of Biology, University of Namur, Namur, Belgium.
- 4Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland.
- 5Tvärminne Zoological Station, Hanko, Finland.
- 6Division of Biology, Linköping University, Linköping, Sweden.
- 7Institute of Evolution, Centre for Ecological Research, Budapest, Hungary.
Abstract
We provide a general theoretical explanation for a longstanding result in spatial ecology: weak dispersal among habitat patches promotes local species richness. Using analytical approximations of spatial Lotka–Volterra competition models, we show that local species persistence in heterogeneous landscapes can be expressed as the balance between the total density across patches and the local exclusion rate. We further demonstrate that local multispecies coexistence is governed by the feasibility domain, linking spatial coexistence to a structural property of nonspatial competitive systems. Together, these results explain why weak dispersal increases local species richness and why this effect strengthens with the number of available patches, i.e., landscape size. We test these predictions using numerical simulations and find that the theory breaks down only when both dispersal and competitive interactions are very strong, in which case dispersal has a unimodal effect on coexistence. In contrast, landscape size retains a positive effect on coexistence whenever an effect is detectable. We then apply the theory to long-term data from a natural metacommunity of microcrustaceans. We detect strong competition among species and find no detectable effect of dispersal rate on local coexistence, whereas species co-occurrence increases with local landscape size, as predicted by theory. Together, our results identify how dispersal, interaction strength, and landscape size jointly regulate local species richness in competitive systems. Author summary: We study a long-standing question in ecology: why does a small amount of movement between habitats often increase the number of species that can live together locally? Although this pattern has been observed in many natural systems, a general explanation has been difficult to establish for communities containing many competing species. Using a mathematical model of species competition across connected habitats, we show that local coexistence depends on a simple balance between two forces. Species are more likely to persist in a habitat when they are abundant across the broader landscape and less likely to persist when strong competition would otherwise drive them locally extinct. This balance allows us to predict when dispersal among habitats promotes biodiversity and when it does not. We also show that the chance that all species coexist locally is closely linked to existing ecological theory developed for isolated communities. We test these predictions using computer simulations and long-term observations of microcrustaceans living in Finnish rock pools. We find strong agreement between theory and data, but also reveal the ecological situations in which it breaks down. Our results provide a unified framework linking dispersal, competition, landscape size, and biodiversity across spatially connected ecosystems.
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BibTeX
@article{laender2026weak,
title = {{Weak dispersal and landscape size inevitably promote local biodiversity in heterogeneous metacommunities of competing species}},
author = {Frederik De Laender and Andrew Gonzalez and Olivia Bleeckx and Dieter Ebert and György Barabás},
journal = {PLOS Computational Biology},
year = {2026},
month = oct,
doi = {10.1371/journal.pcbi.1014028},
url = {https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1014028},
note = {CC BY},
}
RIS
TY - JOUR
TI - Weak dispersal and landscape size inevitably promote local biodiversity in heterogeneous metacommunities of competing species
AU - Frederik De Laender
AU - Andrew Gonzalez
AU - Olivia Bleeckx
AU - Dieter Ebert
AU - György Barabás
PY - 2026
DA - 2026/10/16
JO - PLOS Computational Biology
DO - 10.1371/journal.pcbi.1014028
UR - https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1014028
AB - We provide a general theoretical explanation for a longstanding result in spatial ecology: weak dispersal among habitat patches promotes local species richness. Using analytical approximations of spatial Lotka–Volterra competition models, we show that local species persistence in heterogeneous landscapes can be expressed as the balance between the total density across patches and the local exclusion rate. We further demonstrate that local multispecies coexistence is governed by the feasibility domain, linking spatial coexistence to a structural property of nonspatial competitive systems. Together, these results explain why weak dispersal increases local species richness and why this effect strengthens with the number of available patches, i.e., landscape size. We test these predictions using numerical simulations and find that the theory breaks down only when both dispersal and competitive interactions are very strong, in which case dispersal has a unimodal effect on coexistence. In contrast, landscape size retains a positive effect on coexistence whenever an effect is detectable. We then apply the theory to long-term data from a natural metacommunity of microcrustaceans. We detect strong competition among species and find no detectable effect of dispersal rate on local coexistence, whereas species co-occurrence increases with local landscape size, as predicted by theory. Together, our results identify how dispersal, interaction strength, and landscape size jointly regulate local species richness in competitive systems. Author summary: We study a long-standing question in ecology: why does a small amount of movement between habitats often increase the number of species that can live together locally? Although this pattern has been observed in many natural systems, a general explanation has been difficult to establish for communities containing many competing species. Using a mathematical model of species competition across connected habitats, we show that local coexistence depends on a simple balance between two forces. Species are more likely to persist in a habitat when they are abundant across the broader landscape and less likely to persist when strong competition would otherwise drive them locally extinct. This balance allows us to predict when dispersal among habitats promotes biodiversity and when it does not. We also show that the chance that all species coexist locally is closely linked to existing ecological theory developed for isolated communities. We test these predictions using computer simulations and long-term observations of microcrustaceans living in Finnish rock pools. We find strong agreement between theory and data, but also reveal the ecological situations in which it breaks down. Our results provide a unified framework linking dispersal, competition, landscape size, and biodiversity across spatially connected ecosystems.
SN - 1553-7358
SN - 1553-734X
ER -