Knowledge of species diversity may be sufficient to preserve other dimensions of biodiversity
Our paper, published today in Nature Ecology & Evolution, provides a direct test of the quality of species diversity as a surrogate for conserving phylogenetic and functional diversity
Many biodiversity conservation efforts use species as their fundamental unit, as attested by the 53-year history of the IUCN Red List of Threatened Species and its myriad of applications. However, biodiversity is a multidimensional concept that also encompasses genetic diversity and structure and variation in ecological functions both within and between species and at the level of whole ecosystems.
Increasing pressures from human actions are threatening all dimensions of biodiversity, with species extinctions increasingly leading to the erosion of the tree of life (i.e. phylogenetic diversity) and the loss of ecological functions (i.e. functional diversity). All of these biodiversity dimensions ought to be preserved, as contributions towards all of the United Nations Sustainable Development Goals, and to ensure a sustainable future for our planet.
Several recent studies have concluded that each biodiversity dimension should be incorporated into conservation plans (such as protected area networks) explicitly, either independently or concurrently, because the distribution of areas of high diversity and conservation priority differs significantly between species, phylogenetic and functional biodiversity dimensions.
However, our knowledge of the phylogenetic and functional dimensions of biodiversity remains highly incomplete for most taxa and ecosystems on Earth. Biodiversity knowledge gaps can lead to policy inaction, particularly under stringent monetary constraints, and are therefore a major barrier to the success of biodiversity conservation policies. Given the accelerating pressure on biodiversity worldwide, inaction could be extremely costly and overcoming biodiversity knowledge gaps in a timely manner is paramount.
With this in mind, a consortium of universities (Stony Brook University, Temple University, University of Wisconsin Madison and Auburn University at Montgomery) and applied institutions (NatureServe, IUCN) came together to develop the broadest and most robust approach to testing the degree to which conservation plans targeting species diversity would also represent phylogenetic and functional diversity. Together, we assembled the most comprehensive dataset of geographic distributions, ecological traits, phylogenetic relationships and extinction risk for tetrapods of the Americas to date, by combining the IUCN Red List (species distributions and extinction risk) with data for phylogenetic (led by Hedges) and functional (led by Costa) diversity.
Team meeting at Temple University in March 2016. Top row (left to right): Catherine Graham, Julie Marin, Giovanni Rapacciuolo, and Jocelyn Behm; bottom row (left to right): Matt Helmus, Gabriel Costa, Blair Hedges, Tom Brooks, Bruce Young, and Volker Radeloff in the bottom row.
Our findings indicate that, although the exact configuration of priority areas does indeed vary substantially between biodiversity dimensions, selecting a large enough network of areas using species diversity as a target also represents much of the diversity of evolutionary lineages and ecological attributes. While the definition of “large enough” in this context differs based on the exact conservation strategy employed, most species-based conservation plans can achieve this within 17% of land area – the percentage area targeted by Aichi Target 11 of the Convention on Biological Diversity.
These results have key implications for conservation practitioners and policy-makers. Explicitly incorporating phylogenetic and functional diversity within conservation plans will remain useful where these data already exist. However, for the majority of taxa and ecosystems for which such data are still sparse, conservation actions may proceed confident in the assumption that planning to conserve species will provide a robust surrogate for conserving phylogenetic and functional biodiversity.