New connectivity framework suggests focusing on dispersal constraints

There is an assumption in connectivity modeling that occupied habitat represents suitable dispersal habitat.  However, the type of environment preferred by individuals while dispersing can sometimes differ greatly from the one they prefer for residence and breeding.  Although recent methodological advances have allowed for better predictions of individual dispersal, rarely does connectivity modeling approach dispersal modeling from the perspective of how dispersal may be limited or constrained.  Vasudev et al., in their new paper in Ecography, propose a framework for modeling connectivity that emphasizes a process- and threat-based approach.  They focus on factors that limit dispersal rather than those that provide dispersal routes, and use these to identify geographic space where dispersal may be constrained.

The authors identify three types of dispersal constraints, which constitute their spatial-environment-intrinsic (SEI) framework: spatial constraints created by landscape configuration, external environmental constraints including biotic and abiotic factors, and intrinsic constraints inherent within the characteristics of an individual, group, or population.  These factors influence dispersal by altering demographic patterns (ex. mortality) and/or movement behaviors.  They argue that by focusing on dispersal constraints that arise from a combination of these factors, dispersal is much more likely to be modeled realistically.  By switching the focus of connectivity conservation from “where do individuals potentially disperse?” to “what are the limiting factors to successful dispersal?,” conservation planning can move beyond focusing solely on spatial constraints to encompassing multiple constraints that more accurately reflect how species utilize resources and disperse across the landscape.