A metric of biodiversity that integrates abundance, phylogeny, and function

Background/Question/Methods

The concept of biodiversity is central to ecology and evolutionary biology, especially with regard to concerns over management and sustainability in the face of global change. Yet, there is much debate over what this concept encompasses. My goal is to provide a metric for the concept of biodiversity that encompasses three core components: the abundance of organisms, the phylogenetic relationships among those organisms, and the ecological functions that they perform and ecosystem functions that they affect. This metric is an expansion of the current abundance-based metric that uses Hill numbers, the effective number of types in a sample if all types have the same mean proportional abundance.

Results/Conclusions

To create this integrated measure, I define analogous proportional measures of phylogenetic divergence and functional distinctiveness. Because all three aspects of biodiversity are measured in the same fashion in the same units, an integrated metric can be defined. The combined metric provides understanding of covariation among the components and how management for one component may trade off against others. The metric can be partitioned into components of richness and evenness, and into subsets and variation among subsets, all of which can be related through a simple multiplicative framework. I also propose a set of symbols and terms for all of these aspects of biodiversity that provides clarity of communication and resolves a current contradiction in our use of the term “diversity.” This metric is a complement to, rather than a replacement of, current metrics of phylogenetic and functional diversity.