Taxonomic identification errors generate misleading ecological niche model predictions of an invasive hawkweed

Ecological niche models (ENMs) have been proposed and applied as tools for predicting the extent of exotic species invasion risk and for identifying areas at risk of invasion. Despite the acknowledged concern of relying on occurrence records of variable and (or) unknown quality, the effect of taxonomically uncertain occurrence records on ENMs has not been investigated. We first present a schematic model describing how taxonomic uncertainty could yield varying predictions of invasion potential depending on the spatial characteristics of all versus “reliable” occurrence records. We then explore the issue in more detail by way of a case study on the morphologically and taxonomically difficult yellowdevil hawkweed (Pilosella glomerata (Froel.) Fr.), which is invasive in North America. We compared the climate niche properties and ENM predictions of invasion risk by P. glomerata in North America among models based on (i) all available occurrence records and (ii) records that are taxonomically “reliable”. “Total” records yielded niche properties that were significantly more heterogeneous than reliable records, and consequently, the potential invasion range of P. glomerata based on total records was predicted to be substantially larger. Our results provide rare empirical evidence that vetting occurrence records for taxonomic reliability is of critical importance for niche modeling.