Delimiting Areas of Endemism through Kernel Interpolation

Abstract

We propose a new approach for identification of areas of endemism, the Geographical Interpolation of Endemism (GIE), based on kernel spatial interpolation. This method differs from others in being independent of grid cells. This new approach is based on estimating the overlap between the distribution of species through a kernel interpolation of centroids of species distribution and areas of influence defined from the distance between the centroid and the farthest point of occurrence of each species. We used this method to delimit areas of endemism of spiders from Brazil. To assess the effectiveness of GIE, we analyzed the same data using Parsimony Analysis of Endemism and NDM and compared the areas identified through each method. The analyses using GIE identified 101 areas of endemism of spiders in Brazil GIE demonstrated to be effective in identifying areas of endemism in multiple scales, with fuzzy edges and supported by more synendemic species than in the other methods. The areas of endemism identified with GIE were generally congruent with those identified for other taxonomic groups, suggesting that common processes can be responsible for the origin and maintenance of these biogeographic units.

New records of spiders (Arachnida, Araneae) from the state of Roraima, northern Brazil

“…of synendemic spider species (Oliveira et al 2015). However, our results suggest that these areas harbor a higher number of synendemic species than the survey by Oliveira et al (2015), which therefore had clearly sampling bias. Additionally, the relevancy of our results relies on the use of a high number of species associated with high endemism levels for conservation purposes.…”

“…Brazilian spiders are suitable for the study of diversity patterns and geographical distribution owing to the existence of a large database that includes all records in taxonomic publications, among other records (i.e., Brescovit et al 2011;Oliveira et al 2015). As of 2013, there were 3,425 spider species recorded from Brazil, but about 40% of these species are known only by single records, while about 45% have between two and 15 records, 10% have between 16 and 60 records, and only 2% of the species are represented by more than 100 records (Oliveira et al 2015).…”

“…As of 2013, there were 3,425 spider species recorded from Brazil, but about 40% of these species are known only by single records, while about 45% have between two and 15 records, 10% have between 16 and 60 records, and only 2% of the species are represented by more than 100 records (Oliveira et al 2015). This heterogeneous knowledge is highly influenced by where the main national research institutions, which harbor the most significant collections, and researchers on spider systematics are located.…”

“…Regarding spiders, there is a historical concentration of sampling effort mostly in small regions (Oliveira et al 2015). The states of Pará (e.g., Ricetti & Bonaldo 2008;Bonaldo et al 2009b) and Amazonas (e.g., Höfer & Brescovit 2001;Adis et al 2002;Bonaldo et al 2009a;Dias & Bonaldo 2012) concentrate most of the published spider inventories, collaborating for such heterogeneous knowledge.…”

Arachnids from Araripe Plateau, Ceará, Brazil

“…Although the number of identified species or the total species richness is not especially high, the records herein presented are important as they fill a gap in the known geographical distribution of many arachnid species in the Caatinga biome. These records are important data for proposing and delimiting areas of endemism (see Oliveira et al 2015), one of the most important tools for selecting priority areas for conservation. This list is also a first step for further ecological and taxonomical investigation on the arachnids of the region.…”