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Increased dispersal explains increasing local diversity with global biodiversity declines

Fagan, Brennen ; Pitchford, Jon W. ; Stepney, Susan ; Thomas, Chris D.

Global change biology, 2023-12, Vol.29 (23), p.6713-6726 [Periódico revisado por pares]

Oxford: Blackwell Publishing Ltd

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  • Título:
    Increased dispersal explains increasing local diversity with global biodiversity declines
  • Autor: Fagan, Brennen ; Pitchford, Jon W. ; Stepney, Susan ; Thomas, Chris D.
  • Assuntos: Anthropocene ; Archipelagoes ; Biodiversity ; community assembly ; Community composition ; community dynamics ; Community ecology ; Community involvement ; Dispersal ; Dispersion ; Ecological effects ; ecology ; Endemic species ; Heterogeneity ; Human influences ; invasion ; Invasions ; Invasive species ; Islands ; Population decline ; Robustness ; simulation ; Species diversity ; Species extinction
  • É parte de: Global change biology, 2023-12, Vol.29 (23), p.6713-6726
  • Notas: ObjectType-Article-1
    SourceType-Scholarly Journals-1
    ObjectType-Feature-2
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  • Descrição: The narrative of biodiversity decline in response to human impacts is overly simplistic because different aspects of biodiversity show different trajectories at different spatial scales. It is also debated whether human‐caused biodiversity changes lead to subsequent, accelerating change (cascades) in ecological communities, or alternatively build increasingly robust community networks with decreasing extinction rates and reduced invasibility. Mechanistic approaches are needed that simultaneously reconcile different aspects of biodiversity change, and explore the robustness of communities to further change. We develop a trophically structured, mainland‐archipelago metacommunity model of community assembly. Varying the parameters across model simulations shows that local alpha diversity (the number of species per island) and regional gamma diversity (the total number of species in the archipelago) depend on both the rate of extirpation per island and on the rate of dispersal between islands within the archipelago. In particular, local diversity increases with increased dispersal and heterogeneity between islands, but regional diversity declines because the islands become biotically similar and local one‐island and few‐island species are excluded (homogenisation, or reduced beta diversity). This mirrors changes observed empirically: real islands have gained species (increased local and island‐scale community diversity) with increased human‐assisted transfers of species, but global diversity has declined with the loss of endemic species. However, biological invasions may be self‐limiting. High‐dispersal, high local‐diversity model communities become resistant to subsequent invasions, generating robust species‐community networks unless dispersal is extremely high. A mixed‐up world is likely to lose many species, but the resulting ecological communities may nonetheless be relatively robust. Biodiversity is changing rapidly, but the story is complex, depending on how diversity is measured and whether change accelerates following perturbation or becomes self‐limiting. We track multi‐scale species richness and community robustness for size‐structured model communities using a mainland/island paradigm with varying island heterogeneity and inter‐community dispersal. Our simulations reproduce known empirical patterns across scales—local communities gain species with increasing dispersal but lose endemic species causing ‘global’ diversity declines, and diversity increases with heterogeneity. They also provide new insights. Communities become less invasible as dispersal increases, suggesting that human‐mediated dispersal favours robust communities that resist subsequent change.
  • Editor: Oxford: Blackwell Publishing Ltd
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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