 Often the relation between species and area is represented by the following equation, \(S = kA^z\) where \(S\) is species richness, \(A\) is area, and \(k\) and \(z\) are constants (\(z\) is usually between 0.2 and 0.35). Clearly, as \(A\) increases other things being equal, \(S\) should increase as well. So, it was argued that larger reserves are better for conserving species than smaller ones. Note that if the reserve is isolated from other such reserves then only the extinction rate matters according to the equilibrium model. In 1976, Daniel Simberloff and Lawrence Abele argued that this line of argument was incorrect (Simberloff &amp; Abele 1976). Suppose we have a single reserve of size \(A_1\) and juxtapose it against two with size \(A_2 = A_1/2\) each and that \(z = 0.263\) (this precise value is not important to the argument). Each of the two small reserves would have \(S_2 = kA_{2}^z\) species. If all of the species \(P\) in the pool are capable of dispersing in and surviving in the refuges, then the total expected number of species in both refuges is \(2S_2 - S_2^2/P\); namely the species in either small reserve minus those in both. How many species \(S_1\) would be in the large reserve \(A_1\)? Simberloff and Abele determined that \(S_1 = kA_1^z = k(2A_2)^z = 1.200 \times S_2\). They pointed out that this is less than the total expected number of species \(2S_2 - S_2^2/P\) in the two smaller reserves when \(S_1/P \lt 0.96\). Another important criticism of the use of the equilibrium model in reserve design was that reserves were unlike islands in an ocean (Margules, Higgs, &amp; Rafe 1982). Specifically, the equilibrium model assumes that between the mainland and island no species of the pool can exist; i.e., the immigration rate is zero. However, when we consider areas between reserves, it often is possible for species to occur even if at lower abundances. Thus, the equilibrium model could not be extended without violation of its assumptions to other habitat types such mountain tops (J.H. Brown 1971).