In the small scabious plant,between-population crosses had fitnesses 2.5 times that of the within population crosses (van Treuren et al. 1993). Computer projections indicate that immigration will reduce the extinction risks for two small black rhinoceros populations in East Africa (Box 16.2). Similarly, computer projections demonstrated migration among population fragments to be beneficial in the management of fragmented tule elk
populations in California (McCullough et al. 1996).