On the limitations of graph-theoretic connectivity in spatial ecology and conservation

1. Applications of graph-theoretic connectivity are increasing at an exponential rate in ecology and conservation. Here, limitations of these measures are summarized. 2. Graph-theoretic connectivity measures are fundamentally limited as they require specification of a habitat quality threshold to allow definition of habitat patches (nodes). Frequently, a second threshold (critical dispersal distance) is applied in the identification of graph edges. 3. Graph-theoretic measures are poorly applicable to large-scale, high-resolution, grid-based data that describe distributions of species in habitats of varying quality. 4. Graph-theoretic connectivity primarily concerns the emigration-immigration component of spatial population-dynamics. Therefore, it cannot alone answer questions about the regional population size, resilience or persistence of a focal species. 5. Synthesis and applications: Conservation managers in particular should appreciate these limitations before applying graph-theoretic analysis to spatial conservation planning.