Refugia

Abstract

Biogeographic refugia, if we can identify them, provide indirect evidence of events in the past which have moulded the shape of the present. Generally, refugia are geographic areas whose limits are distinct. They are envisaged as biogeographic arks protecting their passengers from certain extinction during some series of environmental disturbance events. Thus, they tend to be small areas, often tucked into a corner of some larger ecogeographic unit identified today. They also serve another implicit function, as causal elements in the speciation process (Chapter 7). What makes refugia of great interest is the fact that they involve a large subset of a regional biota. These arks are not conceived to explain the survivorship of a single taxon. Rather, they provide a means of explaining large scale survival — and, of necessity, demand pattern as a consequence. In this chapter, the Pleistocene forest refugia hypothesis is examined as a model of these arks.