Flexibility and the use of indicator taxa in the selection of sites for nature reserves

'Minimum' sets of complementary areas represent all species in a region a given number of times. In recent years, conservation assessments have centred around the evaluation of these 'minimum' sets. Previous research shows little overlap between 'minimum' sets and existing nature reserves and between 'minimum' sets for different taxonomic groups. The latter has been used as an argument to discount the use of indicator taxa in the selection of sites for nature reserves. However, these 'minimum' set analyses have only considered a single set for each taxonomic group when there are, in fact, a large number of equally valid 'minimum' sets. We present new methods for evaluating all of these alternative 'minimum' sets. We demonstrate that if all of the sets are evaluated, significantly higher levels of overlap are found between 'minimum' sets and nature reserves, and pairs of 'minimum' sets for different taxonomic groups. Furthermore, significantly higher proportions of species from non-target taxonomic groups are recorded in the 'minimum' sets of target groups. Our results suggest that previous conservation assessments using 'minimum' sets may have been unduly pessimistic.