In biodiversity studies a species is often classified as original when it has few closely related species, a definition\ud that reflects its phylogenetic originality. More recently, studies have focussed on biological or functional traits\ud that reflect the role(s) that species play within communities and ecosystems. This has led many studies to an\ud alternative evaluation of species’ originality: its functional originality. Most indices of species' originality were\ud developed to treat the hierarchical structure of a (phylogenetic) tree. The change in perspective from measures of\ud phylogenetic originality to measures of functional originality thus raises methodological issues particularly\ud around the need to develop indices explicitly appropriate for evaluating functional trait-based originality. We\ud compare indices of species' originality including a new index which we develop to evaluate (1) whether phylogenetic\ud originality could serve as a proxy for functional originality in conservation and ecological studies; (2)\ud whether the transformation of functional data into functional trees modifies the way species are ranked according\ud to their originality measures compared to approaches that directly rely on pairwise functional dissimilarities\ud among species; and more generally, (3) whether different indices provide different views on how original\ud species are from each other, hence reflecting different ecological and evolutionary processes that generated\ud patterns of originality. Using simulations and a real case study, we show that: (1) the strong effects of the choice\ud of a clustering approach can affect reported levels of dissimilarities among species; (2) the tree-based approaches\ud could better reflect the trait-generating processes under constant (Brownian) rates of evolution; and (3) phylogenetic\ud originality measures can depart from functional originality measures when species have large amount\ud of independent evolution. Overall, phylogenies may be used at large scales but cannot replace functional approaches\ud designed for depicting community assembly. Indeed, traits involved in ecological processes may have\ud various histories and thus moderate phylogenetic signals. Our comparative study provides approaches and\ud perspectives on the analysis of originality across biological scales of organization from individuals, through\ud populations, up to the originalities of communities and regions

Natural floating objects (FOBs) have always been a major component of the habitat of pelagic species. Since the 1990s, the number of FOBs in the open ocean has increased greatly as a result of the introduction of fish aggregating devices (FADs) by the industrial tropical tuna purse seine vessels. These changes, and their potential impacts on the species that associate with FOBs, remain poorly understood. Using fisheries observer data, data from satellite-linked tracking buoys attached to FOBs and Lagrangian simulations, this study quantifies the temporal changes in the density and spatial distribution of FOBs due to the use of FADs in the Indian Ocean (IO) between 2006 and 2018. From 2012 to 2018, the entire western IO is impacted, with FADs representing more than 85% of the overall FOBs, natural FOBs less than 10%, and objects originating from pollution 5%. Results also suggest that both FADs and natural FOBs densities are lower in the eastern IO, but this initial investigation highlights the need for further studies. Our study confirms that FADs have greatly modified the density and spatial distribution of FOBs, which highlights the need to investigate potential consequences on the ecology of associated species.