Effects of dynamic taxonomy on rare species and conservation listing: insights from the Iberian vascular flora

Concern has been raised regarding the continually changing nature of biotic taxonomies and how these changes alter perceptions of extinction risk and conservation priority setting. Within this realm, we can identify two distinct problems. First, there is a perception that the activity of a new, fine-scale taxonomy may have an effect in the taxonomy structure producing a taxonomic bias because larger groups may become disproportionably large as a result of new described variation is principally allocated into them. Second, there is an information gap where conservation planning occasionally neglects the most recent taxonomic information derived from fine-scale taxonomy. But, if not, this taxonomic bias has also the potential to alter the proportion of large to small lineages in conservation lists, because most newly described taxa are narrowly distributed and not common, therefore targeted for conservation lists. We use data sources from Iberian vascular flora in 1984 and 2000 to analyze these issues. Results show that rare species description in Iberia has proceeded continuously through time, has been dominated by descriptions in large genera, and shows a sharp increase in description rate since the 1970s. Further, the distribution of newly described taxa reflects proportional representation among groups of differing initial diversity. Finally, change through circumscription (lumping and splitting of former taxa) form part of the description process, but they do not dominate new rare plant taxa. Categorizations of endangered plants appear fairly stable in Spain with 76 % of the most endangered taxa maintaining their species identities through this 16-years period. We conclude that the work of fine scale taxonomy, while representing the bulk of new taxonomic descriptions in Spain, is not biased toward any group size. Although conservation listing can be affected by this taxonomic pattern, we consider the conservation-taxonomy gap to be narrow in Spain.