Integrating abundance and functional traits reveals new global hotspots of fish diversity

• Published in: Nature (London) Vol. 501; no. 7468; pp. 539 - 542
• Main Authors: Stuart-Smith, Rick D., Bates, Amanda E., Lefcheck, Jonathan S., Duffy, J. Emmett, Baker, Susan C., Thomson, Russell J., Stuart-Smith, Jemina F., Hill, Nicole A., Kininmonth, Stuart J., Airoldi, Laura, Becerro, Mikel A., Campbell, Stuart J., Dawson, Terence P., Navarrete, Sergio A., Soler, German A., Strain, Elisabeth M. A., Willis, Trevor J., Edgar, Graham J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.09.2013; Nature Publishing Group
• Subjects: 631/158/670; 631/158/672; 631/158/851; 631/158/853/2006; Animal, plant and microbial ecology; Animals; Applied ecology; Biodiversity; Biological and medical sciences; Biological diversity; Conservation, protection and management of environment and wildlife; Coral Reefs; Ecological function; Ecology; Ecosystems; Eukaryotes; Fish; Fishes; Fishes - classification; Fundamental and applied biological sciences. Psychology; Genetic aspects; Geography; Humanities and Social Sciences; letter; Marine fish; Methods; multidisciplinary; Nutrient cycles; Ocean basins; Pacific Ocean; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Population Density; Science; Species diversity; Species richness; Species Specificity; Temperature; Tropical Climate; Tropical environments; World ocean; Pacific Ocean; Australia; United States; Sweden; Marine environment; Species diversity; Vertebrata; Geographic distribution; Pisces; Hot spot; Ecosystem functioning; Biodiversity; Animal conservation; Species richness; Ecological abundance
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/nature12529

Global reef fish diversity is studied with metrics incorporating species abundances and functional traits; these identify diversity hotspots corresponding to the diversity of functional traits amongst individuals in the community, and greater evenness in the abundance of reef fishes at higher latitudes, findings that contrast with patterns reported previously using traditional richness-based methods. Cooler biodiversity hotspots revealed Traditional measures of biodiversity record species richness across different areas — in other words, they just count the number of species. This approach takes no account of the fact that different species will have different abundances, or that the range of functional traits present in a community is not dependent solely on the number of species. This paper presents a new measure of functional diversity, incorporating species abundances and functional traits into a global census of a vertebrate group —2,473 marine reef fish species — at 1,844 sites. The results reveal previously unknown diversity hotspots in temperate regions and in the Tropical Eastern Pacific, which are outside the species-rich tropical regions traditionally associated with high biodiversity. Species richness has dominated our view of global biodiversity patterns for centuries 1 , 2 . The dominance of this paradigm is reflected in the focus by ecologists and conservation managers on richness and associated occurrence-based measures for understanding drivers of broad-scale diversity patterns and as a biological basis for management 3 , 4 . However, this is changing rapidly, as it is now recognized that not only the number of species but the species present, their phenotypes and the number of individuals of each species are critical in determining the nature and strength of the relationships between species diversity and a range of ecological functions (such as biomass production and nutrient cycling) 5 . Integrating these measures should provide a more relevant representation of global biodiversity patterns in terms of ecological functions than that provided by simple species counts. Here we provide comparisons of a traditional global biodiversity distribution measure based on richness with metrics that incorporate species abundances and functional traits. We use data from standardized quantitative surveys of 2,473 marine reef fish species at 1,844 sites, spanning 133 degrees of latitude from all ocean basins, to identify new diversity hotspots in some temperate regions and the tropical eastern Pacific Ocean. These relate to high diversity of functional traits amongst individuals in the community (calculated using Rao’s Q 6 ), and differ from previously reported patterns in functional diversity and richness for terrestrial animals, which emphasize species-rich tropical regions only 7 , 8 . There is a global trend for greater evenness in the number of individuals of each species, across the reef fish species observed at sites (‘community evenness’), at higher latitudes. This contributes to the distribution of functional diversity hotspots and contrasts with well-known latitudinal gradients in richness 2 , 4 . Our findings suggest that the contribution of species diversity to a range of ecosystem functions varies over large scales, and imply that in tropical regions, which have higher numbers of species, each species contributes proportionally less to community-level ecological processes on average than species in temperate regions. Metrics of ecological function usefully complement metrics of species diversity in conservation management, including when identifying planning priorities and when tracking changes to biodiversity values.