Answers to Hone Your Problem-Solving Skills Questions
1. Species A is relatively insensitive to shape until the ratio of perimeter to area is very high, and therefore species A may be found in both reserve designs. In contrast, species B is more sensitive to a large amount of edge, so it has a higher probability of occurrence in patches with lower perimeter to area ratio, and thus design 1 would be best.
Species C does best with intermediate perimeter to area ratio and thus would do better with design 2, which has more edge than design 1.2. Greater food availability at the edges, such as the occurrence and abundance of food plants or prey that thrive in edge environments, would enhance the occurrence of a species there, while lower food availability would have the opposite effect. Lower diversity of species in patches with extensive edges may decrease food availability. Edges may enhance detection of predators or prey and also provide greater habitat for escape of predation. The physical environment at edges may be more extreme than at the core habitat in the patches, excluding some species. Some species may need extensive core habitat to protect and rear their young and so avoid patches with large amounts of edge.