Mounting challenges from man-made environmental change means measuring and tracking changes in biodiversity—the total living
natural assets on earth—is becoming increasingly more important. Scientists have for decades debated how best to measure biodiversity
and to track changes in its properties.
Zeta diversity, presented in this paper by Hui and McGeoch, is the average number of species shared by any number of sites or habitats.
It can be used to calculate a broad range of existing diversity metrics, and to quantify continuous change in biodiversity over landscapes.
It can also be used for examining if environmental change affects rare and common species differently, and to test hypotheses about the
relative importance of deterministic (niche-based) versus stochastic (neutral) processes in generating patterns in biodiversity.
In the past, changes in the presence or absence of species in a community between sites – or over time – was calculated by
working out which species any and all pairs of sites have in common. This is called diversity turnover, or beta diversity. Estimating
changes in biodiversity by comparing two sites at a time in this way has become the norm. However, as soon as three or more sites are
involved beta diversity can’t partition the total community into components uniquely shared by each pair of sites or shared by all sites.
We are missing important information on the nature and condition of biodiversity with these pairwise beta diversity and individual site
There is a second important challenge in the study and description of biodiversity. This is the fact that different mathematical
languages are used to calculate and depict various diversity patterns and relationships. As a result it has not been possible to integrate
various models of biodiversity. Doing so is one of ecology’s main goals. Zeta diversity provides a mathematical link between the patterns
that we see, for example, in species richness, species endemism and relative range sizes.
Zeta diversity provides a common currency for application across a broad range of problems in ecology and conservation planning, for
understanding the processes that drive patterns in biodiversity and the impacts of global change.
By providing a continuous biodiversity turnover metric, zeta diversity is particularly useful for assessing
the conservation status of protected areas not only based on endangered species but also common ones, such as the Lilac-breasted
roller (Coracias caudata) in Kruger National Park (South Africa). Photo credit: C. Hui.
Read the paper:
Hui, C. & McGeoch, M.A. (2014) Zeta diversity as a concept and metric that unifies incidence-based biodiversity patterns. American Naturalist, in press.
For more information, contact Cang Hui at email@example.com or visit http://math.sun.ac.za/hui