Metapopulation dynamics of wetland species

Abstract

For species inhabiting naturally patchy or fragmented landscapes, conservation often is guided by metapopulation theory. A metapopulation is a set of spatially separated populations connected by movement of individuals among populations. The metapopulation can persist, despite extinctions of local populations, if populations are connected enough to allow for adequate recolonization of vacant habitat. Because wetlands occur as geographically isolated habitats, many wet- land-associated species could display metapopulation dynamics. However, clas- sical metapopulations may be rare, and metapopulations can have a diversity of spatial structures. Practical metapopulation approaches are grounded in the "area- isolation paradigm" in which the area of a habitat patch is the main predictor of local extinctions, and connectivity to other source populations is the main pre- dictor of colonization. The generality of the area-isolation paradigm has been questioned, however, and its shortcomings relate to the need to consider habitat heterogeneity. Wetlands can differ in habitat quality and they are embedded in a heterogeneous terrestrial matrix. Functional connectivity of metapopulations depends on how movements of individuals interact with the terrestrial habitat matrix. Despite these complexities, recognition of metapopulation dynamics for wetland species has forced managers to think about biodiversity conservation at landscape scales and highlights the importance of wetland-upland linkages.