We investigated the existence of chorotypes – assemblages of species with similar
geographical ranges – of invasive species in a host territory, and their potential use to
advocate similar control or management strategies for species in the same chorotype. We analysed the distribution of 13 exotic terrestrial vertebrate species (six
birds, six mammals, and one reptile) with well-known distributions in mainland
Spain. We used the presence/absence data on a grid of 10 km × 10 km UTM cells
from the Atlases of terrestrial vertebrates of Spain. These data were aggregated to a
grid of 50 km × 50 km UTM cells, because it entailed no loss of meaningful information and allowed dealing with a much lower number of cells. Using cluster analysis
and a probabilistic assessment of the classification, we identified seven significant
chorotypes: four multispecific and three monospecific. The compound chorotypes
grouped together species that tended to share certain characteristics about their
introduction, release cause, establishment, and spread. We modelled the chorotypes
using a favourability function based on a generalized linear model and 31 variables
related to spatial situation, topography, lithology, climatic stability, energy availability,
water availability, disturbances, productivity, and human activity. Climatic factors
affected the favourability for every chorotype, whereas human variables had a high
influence in the distribution of three chorotypes involving eight species. On the basis
of these variables, we identified favourable areas for all the chorotypes in mainland
Spain. The favourability for a chorotype in an area may be a useful criterion for
evaluating the local conservation concern due to the whole set of species. Favourable but unoccupied areas can be used to infer possible colonization areas for each
chorotype. We recommend using chorotypes to optimize broad-scale surveillance of
invasive species.
