Background: Refugia are island-like habitats that are linked to long-term environmental stability and, as a result, high endemism. Conservation of refugia and endemism hotspots should be based on a deep ecological and evolutionary understanding of their functioning, which remains limited. Although functional traits can provide such insights, a corresponding, coherent framework is lacking. Proposed Framework: Plant communities in refugia and endemism hotspots should, due to long-term environmental stability, display unique functional characteristics linked to distinct phylogenetic patterns. Therefore, such communities should be characterized by a functional signature that exhibits: (1) distinct values and combinations of traits, (2) higher functional diversity and (3) a prevalence of similar traits belonging to more distantly related lineages inside, compared to outside, of endemism hotspots and refugia. While the limited functional trait data available from refugia and endemism hotspots do not allow these predictions to be tested rigorously, three potential applications of the functional signature in biogeography and conservation planning are highlighted. Firstly, it allows the functional characteristics of endemism hotspots and refugia to be identified. Secondly, the strength of the functional signature can be compared among these entities, and with the surrounding landscape, to provide an estimate of the capacity of endemism hotspots and refugia to buffer environmental changes. Finally, the pattern of the functional signature can reveal ecological and evolutionary processes driving community assembly and functioning, which can assist in predicting the effect of environmental changes (e.g. climate, land-use) on communities in endemism hotspots and refugia. Conclusion: The proposed functional signature concept allows the systematic integration of plant functional traits and phylogeny into the study of endemism hotspots and refugia, but more data on functional traits in these entities are urgently needed. Overcoming this limitation would facilitate rigorous testing of the proposed predictions for the functional signature, advancing the eco-evolutionary understanding of endemism hotspots and refugia.

Curtin Institute for Biodiversity and Climate ARC Centre for Mine Site Restoration and School of Molecular and Life Sciences Curtin University Bentley Australia

Department of Environmental Science and Policy University of California Davis Davis CA USA

Department of Pathology Microbiology and Immunology School of Veterinary Medicine University of California Davis CA USA

Natural and Built Environments Research Centre School of Natural and Built Environments University of South Australia GPO SA Adelaide Australia Future Industries Institute University of South Australia SA Adelaide Australia Biodiversity Macroecology and Biogeography Faculty of Forest Sciences University of Goettingen Göttingen Germany

School of Biological Sciences The University of Western Australia Crawley WA Perth Australia Department of Geography and Environmental Studies Stellenbosch University Matieland Stellenbosch South Africa

School of Biological Sciences The University of Western Australia Crawley WA Perth Australia Institute of Botany Academy of Sciences of the Czech Republic Třeboň Czech Republic

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