The Community Genetic Distribution (CGD): A unifying measure for monitoring biodiversity change

Isaac Overcast , Irene Calderon-Sanou, Simon Creer, Virginia Dominguez-Garcia, Oskar Hagen, Michael Hickerson, Theresa Jörger-Hickfang, Henrik Krehenwinkel, Jay T Lennon, Laura Méndez, Maria Méndez, Renske Onstein, Henrique M. Pereira, Clara Qin , Douglas W Yu, Damaris Zurell, Rosemary G. Gillespie

Monitoring the condition of ecological communities is essential to understanding, managing and conserving biodiversity. Much needed is a means to measure holistic properties that emerge from ecological communities, in other words attributes that characterize communities as a whole rather than individual species or sets of species. Here, we propose the Community Genetic Distribution (CGD) as a novel metric that captures these emergent properties of ecological communities by integrating genetic data from a comprehensive sample of the community. The CGD compliments existing taxon-based metrics, focusing on properties that emerge from the interacting set of species within a given local community; as such, it is unifying across taxa, economically scalable, and geographically transferable. Using high-throughput biodiversity genetic inventories, the CGD captures information about past ecological and evolutionary dynamics that have shaped the local community, whether through local co-evolution and speciation within an isolated community, dispersal and ecological filtering from a larger co-evolved regional pool, or recent colonization from a novel anthropogenic pool. Here, we present empirical case studies demonstrating how CGD, derived from metabarcoding datasets, varies in space and time in response to human disturbances, and effectively captures patterns associated with restoration and succession gradients. These insights enhance our understanding of the community-level genetic condition and help develop reliable indicator metrics to assess ecological and evolutionary degradation. The CGD complements existing essential biodiversity variables and provides the basis for developing novel indicators of community status and integrity, and can thus directly contribute to the targets of the Kunming-Montreal Global Biodiversity Framework.