What do genetics and ecology tell us about the design of nature reserves?

Abstract

The SLOSS (single large or several small) debate is no longer an issue in the discussion about the optimal size of nature reserves. The best way to estimate the minimum sizes of reserves may be a three-step process: (1) identify target or keystone species whose disappearance would significantly decrease the value or species diversity of the reserve; (2) determine the minimum number of individuals in a population needed to guarantee a high probability of survival for these species; (3) using known densities, estimate the area needed to sustain the minimum number. The forces that affect population viability and determine MVPs (minimum viable populations) are extremely complex. Thoughtful estimates of MVPs for many animal species are rarely lower than an effective size of a few hundred.Attempts to save only common or smaller species in a community will usually be ill-fated because of the web of ecological relationships between species, including the importance of predation and herbivory in the maintenance of species diversity. Other topics discussed include the complementarity of conservation goals, the problematic function of corridors and the value of buffer zones.