Global patterns and drivers of raptor phylogenetic and functional diversity

Abstract

Aim Raptors, a highly threatened but ecologically important group of birds, have been recognized as a good proxy for overall biodiversity in conservation planning. However, previous work on raptor diversity focused predominantly on taxonomic diversity. Here, we assess the global patterns of raptor taxonomic, phylogenetic and functional diversity and their association with current and historical environmental factors. Location Global. Time period Present day. Major taxa studied Raptors. Methods We compiled information from distribution maps, global trait datasets and avian phylogenies for all extant raptors. We used generalized least squares (GLS) to assess the relationship between historical and contemporary environmental predictors and species richness, phylogenetic diversity [Faith's phylogenetic diversity index (Faith's PD), mean pairwise distance (MPD) and mean nearest taxon distance (MNTD)] and functional diversity of traits related to raptor morphology, lifestyles, diet, foraging and vagility, while controlling for spatial autocorrelation. Results Raptor taxonomic diversity peaked in tropical regions and nearby mountain ranges. After controlling for species richness, species‐poor assemblages in high latitudes and deserts were more phylogenetically and functionally diverse than expected by chance. In species‐rich assemblages, diet and foraging traits had greater variation, whereas morphological traits had less variation than expected, suggesting that species packing promoted adaptive radiation in these assemblages. Historical climate influenced phylogenetic diversity and functional diversity of morphological, foraging and diet traits, leaving a signal of evolutionary history on modern assemblages. Human footprint was also an important driver of MPD and of niche and vagility trait functional diversity, with higher phylogenetic diversity in disturbed areas and with higher functional diversity in regions with intermediate levels of disturbance. Main conclusions Both palaeoclimate and contemporary environmental conditions are important drivers of raptor phylogenetic and functional diversity. We found large mismatches among taxonomic, functional and phylogenetic diversity, demonstrating how different processes filter lineages and species traits shaping raptor assemblages. Our results highlight the need to consider multiple dimensions of diversity to inform conservation planning better when using raptors as umbrella species.