DOI: 10.5061/dryad.wm37pvmq1
title: Data from: Geographic and climatic constraints on bioregionalization of European ants

description: Aim: Biogeographic regionalization is scant for most insect groups due to
 shortfalls in distribution and phylogenetic information, namely the
 Wallacean and Darwinian shortfalls respectively. Here, we focused on the
 European ants and compared new techniques to classical analyses based on
 regional lists and taxonomic methods. We asked the following: 1) Can
 grid-based regionalizations using novel distribution data improve
 biogeographic transitions? and 2) Can phylogenetic approaches reveal new
 insights regarding ant evolutionary history? Location: Europe and
 Anatolia. Taxon: Ants (Formicidae). Methods: First, we developed a refined
 database integrating the occurrences of 747 ant species across 207 regions
 of Europe and Anatolia, based on newly expert-validated records derived
 from the existing Global Ant Biodiversity Informatics (GABI) database.
 Using range estimates for these species derived from polygons and species
 distribution modelling, we produced species assemblages in 50 × 50 km grid
 cells. We calculated taxonomic and phylogenetic turnover of ant
 assemblages, then performed a hierarchical clustering procedure to
 delineate biogeographic structure. Results: At both the regional list- and
 grid assemblage-levels, the Mediterranean has higher turnover and more
 biogeographic regions than northern Europe, both taxonomically and
 phylogenetically. Delineations based on grid assemblages detected more
 detailed biogeographic transitions, while those based on regional lists
 showed stronger insularity in biogeographic structure. The phylogenetic
 regionalization suggested a very similar spatial structure but varied
 affinities between assemblages in comparison to the taxonomic approach.
 Main conclusions: Here, we integrated expert-validated regional lists,
 species distribution modelling, and a recent phylogeny to tackle Wallacean
 and Darwinian shortfalls for an important insect group by developing a
 next-generation map of biogeographic regionalization for European ants.
 The results of this study suggest strong constraints from geographic
 barriers and potential effects of climatic history on ant distributions
 and evolutionary history and also provide baseline spatial information for
 future investigations of regional insect distributions.
description: 1. Regional species lists of the western Palearctic ants:
 This database is derived from the
 Global Ant Biodiversity Informatics (GABI, Guénard et al., 2017) but
 features a higher spatial resolution for the region. Ultimately, we
 compiled native ant taxa occurrence information for each of the 207
 geographic divisions (i.e., regional lists) for the western Palearctic
 realm, which was previously divided to 57 regions in GABI. Our definition
 of the western Palearctic realm does not include North Africa and the
 Arabian Peninsula because of historically poor sampling and the lack of
 recent taxonomic revisions for species in those regions.
 Geographical divisions used in the
 database were delimited based on either administrative region (GADM,
 version 2.8, accessed 1<sup>st</sup> Sep. 2020) or modified
 areas based on the physical geographic area (e.g., islands and mountains),
 depending on data availability. Preliminary versions of the
 dataset were validated by ant experts (co-authors of this study) who
 identified dubious records and provided additional information (e.g.,
 unpublished or missing records) to complete and provide more accurate ant
 range maps. Occurrence records were deemed dubious for reasons including
 nomenclatural changes in recent taxonomic revisions, outdated taxonomy,
 and misidentifications (which can be numerous in older literature or
 databases). For all ant taxa in our database, we also verified
 nomenclature based on AntCat, an online, global catalog of ants (Bolton,
 2021), with validation and inclusion of taxa up to July
 1<sup>st</sup> 2021. Here, we treated valid subspecies as
 species in our analysis, which resulted in a total of 747 valid native
 species (including 40 subspecies) for regional lists.
 2. Binary range maps
 of the western Palearctic ants: Ranges were estimated for low-data species
 (&lt;5 occurrence records) with univalue polygons (either buffered [30
 km] points or convex/alpha hull, depending on data availability), and for
 species with sufficient data (≥ 5 occurrence records) using SDMs. We used
 the presence-background machine-learning algorithm Maxent to train models
 over a study extent defined by their polygon range estimate (buffered
 alpha hull) using 19 bioclimatic predictor variables at 10 arcminute
 resolution (~20 km at the equator) from Worldclim 2.0 (Fick &
 Hijmans 2017). We tuned models for optimal complexity (i.e., combinations
 of feature classes and regularization multipliers) using sequential
 criteria of cross-validation results (based on the 10 percentile omission
 rate and validation AUC; Radosavljevic & Anderson 2014) with the R
 package ENMeval 2.0.0 (Kass et al. 2021). We used these tuned
 models to make predictions of suitability over the species’ study extents,
 effectively constraining range estimates to the limits of the occurrence
 data, and made them binary (presence/absence predictions) by thresholding
 with the 10 percentile omission value. Range estimates represented by
 polygons for low-data species were converted to 10 arcminute grid cells to
 align with the modeled range estimates. Detailed metadata of SDMs can be
 found in the metadata as the ODMAP protocol format (Zurell et al.,
 2020).
description: All those data are part of an unpublished database: the European
 Ant Distribution (EUAD) database, we are still working on it and its open
 access. Thus we highly recommend you to contact us first if you want to
 use this dataset.