A climate suitability index for species distribution modelling applied to terrestrial arthropods in the Mediterranean region

Abstract. Climate change poses significant threats to global biodiversity, particularly impacting arthropods due to their sensitivity to shifts in temperature and precipitation, as well as other environmental conditions. These changes impact the suitability of their habitats, alter ecological interactions, and consequently affect the distribution and survival of species. Understanding how climate variability influences the ecological niches of arthropods is crucial for predicting future biodiversity patterns and implementing effective conservation strategies. This study introduces a simple index designed to model species' distribution on the basis of their climatic niche, with a specific focus on terrestrial Mediterranean arthropods. This approach leverages regional climate model data to construct a climatology of a species's preferred habitat, based on historically observed locations. This index offers a straightforward and rapid means to assess the resilience and vulnerability of arthropod populations and could be applied to future studies aiming to shed light on how climate change could affect the fundamental niches of terrestrial arthropods. The analysis revealed that the method is most reliable for species with observations exceeding 1000 points and climate datasets of high resolutions (although the latter had a smaller influence on the results). This study offers a proof of concept for the proposed index, demonstrating its potential utility in guiding conservation strategies and mitigating the adverse effects of climate change on arthropod habitats.