Using higher taxa as surrogates of species-level data in three Portuguese protected areas: a case study on Spheciformes (Hymenoptera)

Protected areas are the focus of most conservation efforts worldwide. Despite vast amount of investment in protected areas, biodiversity loss continues. This has led to increasing efforts to develop measures to assess the effectiveness of protected areas. The reliability of these measures depends on the quality of the information collected. However, because the resources available for the collection of information are limited, several strategies have been developed to reduce the resources necessary. In this study the combination of two resource reduction approaches-bioindicator and higher-taxa-is proposed. Spheciformes have been found to be useful as biodiversity, ecological and environmental indicators. Identification to the species level is usually very costly, but the use of genus-level information has been suggested. Tribe- and genus-level data for Spheciformes were assessed for their ability to predict the number of species independently of other variables-sampling area, geographic location, vegetation type, disturbance regime, and sampling effort-at three Portuguese protected areas. Tribe and genus-level data were found to be good indicators, with genus being the more reliable taxonomic level. Sampling effort was the only external variable that affected the relationship between species and higher-taxa richness. Genus-level data were also found to be useful for ranking sites according to richness or composition, and for determining richness-based and rarity-based complementary sets of sites for conservation. Using genus richness as a surrogate for species richness seems a promising approach for monitoring and contributing to the establishment of protected areas in Portugal and the entire Mediterranean region.