Quantifying species distribution within the functional space

Abstract Multidimensional representations of functional diversity help visualize species and organism distribution in functional space, providing insights into the mechanisms regulating community assembly and ecosystem functioning. Typically, the species distributions in functional space are represented by richness, divergence (or dispersion) and evenness (or regularity). While these dimensions quantify the overall structure of species distribution, they overlook how exactly species are scattered within the functional space, particularly the fine‐scale spatial patterns that may reveal additional ecological or evolutionary dynamics. We introduce a novel framework to quantify species' functional arrangement within the functional space, capturing patterns across broad and fine scales. We detail the construction of a functional space and propose statistics to assess species functional arrangement—the cumulative proportion of pairwise neighbours (PN cp ) and the cumulative proportion of nearest neighbours (NN cp ). We also outline guidelines for evaluating departures from randomness using null models, including random displacement and random selection from species pool. To demonstrate this framework, we tested it in simulated scenarios and analysed the functional arrangement patterns of vascular plant species on Surtsey Island. In the simulated scenarios, the framework correctly identified simulated patterns at multiple scales. As for the colonization of Surtsey Island, our findings showed a gradual reorganization of species within the functional space. Initially random, the distribution shifted towards clustering, reflecting increasing habitat complexity and the formation of ecological relationships among plant species. This pattern aligns with succession theory, where early arrivals create conditions that favour later colonizers, leading to a more interconnected and structured ecosystem. Our framework allows to advance from global (richness, dispersion and evenness) to fine‐scale (arrangement) functional distribution patterns, adopting rigorous, quantitative methods that can test specific ecological hypotheses and uncover deeper insights into community assembly and the functioning of ecosystems. By assessing functional arrangement, it enables researchers to address a broader range of functional diversity questions than previously possible. The methods presented here offer a powerful approach to uncover and interpret complex patterns in functional diversity occurring at multiple scales.