Topology-based conservation of dynamic pond meta-communities: insights from Algerian charophytes

Biodiversity conservation in fragmented landscapes requires balancing the protection of connected patches, ensuring gene flow and meta-population persistence, and of isolated nodes, hosting unique species pools and contributing the most to beta-diversity. Most importantly, it requires addressing the dynamical nature of spatial connectivity patterns that may dramatically change over time. Here we demonstrate how novel topological approaches from the field of computational topology can foster the conservation of fragile and uniquely important meta-communities by tracking their evolution in space and time. Specifically, we studied 4-year temporal network dynamics of charophyte meta-communities of Algerian temporary ponds using a combination of graph spectral approaches and zig-zag persistence. First, our approach revealed steady climate-driven oscillations in network topology highlighting meta-community transitions between lowly and highly connected states. Second, by targeted simulations of node removal, we demonstrated that meta-community dynamic stability depends on a small set of key ponds that are not necessarily the most connected at any single time. Finally, the analysis allowed identifying both the ponds contributing the most to the temporal connectivity and those that through isolation preserve unique biodiversity reservoirs. Overall the proposed topological approach, easily generalizable to any system with time-series community data, provides a multi-purpose prioritization map optimizing at the same time the conservation of global meta-community dynamics and of local biodiversity hot-spots.