Making the most of scarce data: Mapping distribution range and variation in population abundance of a threatened narrow-range endemic plant

Abstract The design of effective strategies for the conservation and management of threatened narrow-range species requires basic knowledge on their geographic distribution and abundance. When such knowledge is lacking, modelling techniques can provide an opportunity to acquire basic information and incorporate it immediately into conservation programs. This study used ecological niche modelling to map the potential distribution range and rangewide variation in population abundance of a threatened narrow-range endemic plant, Antirrhinum lopesianum Rothm. in the Iberian Peninsula. We simulated the potential geographic distribution of the species using the Ensemble Modelling approach based on 28 species occurrences and a set of readily available environmental data (Landsat 8 OLI/TIRS and LiDAR) and created a spatial model of the distance to the niche centroid. We tested the relationships between 35 records with abundance data for the species and their distance to the niche centroid using generalized regression models, and the resulting model was used to predict spatial estimations of A. lopesianum abundance across its entire potential distribution range. The ecological niche model of A. lopesianum covered the most suitable areas located along a narrow strip on the banks of the River Duero and River Sabor. We found a robust and negative relationship between observed abundance for the taxon and distance to the niche centroid. The spatially explicit model presented here provides a reliable tool for regional/global management and conservation of A. lopesianum and an approach applicable for other narrow-range endemic plants. Finally, this approach maximization the exploitation of basic information through open resources (software and environmental variables), which makes it of high interest for institutions with limited resources.