Emilio García-Roselló

Accurate species distribution data are essential for effective conservation planning; however, they are often incomplete or spatially biased. Such limitations may obscure real biodiversity patterns and undermine the reliability of cross-taxon congruence analyses. Here, we assess how data quality and sampling effort influence estimates of cross-taxon congruence in insect species richness patterns across the Iberian Peninsula and the Balearic Islands. Using a large, curated georeferenced database (> 845,000 records comprising 1,808 species) covering four insect groups (butterflies, moths, dung beetles, and water beetles), we evaluated inventory completeness with species accumulation curves and identified well-surveyed cells (≥ 70% completeness and final slope ≤ 0.1) under four scenarios representing progressively higher levels of information reliability. Species richness patterns showed clear geographical structure, with richness hotspots generally associated with major mountain systems, although their specific locations differed among taxonomic groups. Across all dataset scenarios, cross-taxon correlations in species richness were generally positive but moderate. Importantly, congruence tended to decline, as analyses were progressively restricted to well-surveyed cells, suggesting that low-quality data may artificially inflate the apparent agreement among taxa. The strongest congruence was observed between taxonomic groups belonging to the same order (Coleoptera or Lepidoptera), whereas relationships between orders were markedly weaker. Overall, our results suggest that apparent cross-taxon congruence in insect species richness is strongly influenced by data quality and taxonomic relatedness. These findings highlight the need for multi-taxon approaches and for explicitly accounting for sampling bias when using surrogate taxa in biodiversity assessments and conservation planning.

Arthropods constitute the bulk of global biodiversity, being the most diverse metazoan phylum on the planet. Despite the relevance of arthropods, our knowledge about them remains limited, partly due to the scarcity of reliable faunistic data. The Iberian Peninsula is part of one of the global biodiversity hotspots, the Mediterranean Basin. However, very little is known on the ecology and spatial distribution of many Iberian arthropod species. We provide a database on the distribution of Ibero-Balearic arthropods (the IberArthro database) belonging to 10 taxonomic groups: Coleoptera (Aquatic), Coleoptera (Scarabaeoidea), Collembola, Hymenoptera (Apoidea), Lepidoptera (Noctuoidea), Lepidoptera (Papilionoidea), Neuropterida, Opiliones, Plecoptera and Trichoptera. The database contains 1 006 768 records with associated geographic data (at 10 × 10 km grid squares), compiled from various sources and validated by specialists in each group. These records cover 4612 species and subspecies, spanning from the 18th century to February 2024. This database represents an unprecedented advance in understanding the distribution of Iberian arthropod biodiversity and its conservation. The complete dataset is provided in Darwin Core Archive format and is available through the Global Biodiversity Information Facility (GBIF).

This study introduces a novel approach to leverage high‐resolution historical climate data and opportunistically collected historical species occurrence data for detecting adaptive responses to global change. We applied this procedure to the temperature data and the most comprehensive Iberian dataset of dung beetle occurrences as an illustrative example. To understand how populations of different species are responding, we devised a procedure that compares the temporal trend of spatial and temperature variables at the locations and times of all the occurrence data collection (overall trend) with the specific temporal trends among the occurrences of each species. The prevalence of various species responses is linked to life history or taxonomic characteristics, enabling the identification of key factors influencing the propensity to experience different effects from climate change. Our findings suggest that nearly half of the Iberian dung beetle species may be adversely affected by temperature increases, with a geographic shift being the most common response. The results generated through the proposed methodology should be regarded as preliminary information, serving to formulate hypotheses about the diverse responses of species to climate change and aiding in the selection of candidate species capable of coping with challenges posed by changing temperatures.

The Global Biodiversity Information Facility (GBIF) is the largest databank on primary biodiversity data. We examined the completeness and geographical biases for all insect data on GBIF to determine its representativeness. Our results demonstrate that GBIF is far from providing a reliable representation about the global distribution of insects. Despite the growing number of records during the last years, few spatial units are well‐surveyed. At coarse resolutions, 34% of the world terrestrial cells lack data and barely 0.5% have completeness values above 90%. Insects are crucial in many ecological functions, and their alarming decline makes it more pressing to have a representative sample to improve our predictive capacity. However, the dynamic nature of species distributions and the strength of anthropogenic forces call for immediate conservation decisions that cannot wait for the empirical data on the identity and distribution of insects.

Understanding the factors shaping species' distributions is a key longstanding topic in ecology with unresolved issues. The aims were to test whether the relative contribution of abiotic factors that set the geographical range of freshwater fish species may vary spatially and/or may depend on the geographical extent that is being considered. The relative contribution of factors, to discriminate between the conditions prevailing in the area where the species is present and those existing in the considered extent, was estimated with the instability index included in the R package SPEDInstabR. We used 3 different extent sizes: 1) each river basin where the species is present (local); 2) all river basins where the species is present (regional); and 3) the whole Earth (global). We used a data set of 16,543 freshwater fish species with a total of 845,764 geographical records, together with bioclimatic and topographic variables. Factors associated with temperature and altitude show the highest relative contribution to explain the distribution of freshwater fishes at the smaller considered extent. Altitude and a mix of factors associated with temperature and precipitation were more important when using the regional extent. Factors associated with precipitation show the highest contribution when using the global extent. There was also spatial variability in the importance of factors, both between species and within species and from region to region. Factors associated with precipitation show a clear latitudinal trend of decreasing in importance toward the equator.