Incorporating phylogeographic information in alien bird distribution models increases geographic extent but not accuracy of predictions

Abstract

Species distribution models (SDM) have been proposed as valuable first screening tools for predicting species responses to new environmental conditions. SDMs are usually conducted at the species level, assuming that species-environment relationships are a species-specific feature that do not evolve and show no variability across a species’ range. However, broad environmental tolerances at the species level can encompass narrower and different environmental tolerances for specific lineages or populations. In this study, we evaluate whether SDMs that account for within-taxon niche variation in climate and human-habitat associations provide better fits between projected distributions and real occurrence data for alien bird species than species-level SDMs. Our study focuses on eight alien bird species with established alien populations for which detailed phylogeographic information was available. Similarity in climates and human disturbance conditions occupied by different phylogenetic groups within species was low and not greater than random expectations. Accounting for intraspecific niche variation in SDMs modified the distribution and extent of suitable habitat predicted as susceptible to invasion, but did not result in more accurate model predictions in alien ranges. Until more accurate information on intraspecific variability is available, species-level models can be reasonable candidates. When phylogeographic information is available, the use of the most conservative criterion (i.e. to model both species and lineages on the basis of the actual range) is recommended.