Dimensions: Collaborative Research: Processes that generate and maintain phylogenetic, genetic, and functional diversity of the freshwater mussel holobiont across multiple scales

The term 'holobiont' is used to refer to an organism as the sum of the interactions between the host and the microbes associated with them (the 'microbiome'). Yet, the extent to which diversity at different levels of biological organization in host and microbiome communities influence functional diversity within ecosystems represents a considerable gap in our understanding of global biodiversity. This project will represent a landmark in understanding what generates and maintains biodiversity in river ecosystems. Freshwater mussels are a highly imperiled, species-rich group of animals that play critical roles in rivers through their filter-feeding and cycling of nutrients. Although the ecological value of freshwater mussels is widely appreciated, little is known about how factors like genetic diversity of individual species, species composition and diversity of mussel communities, or interactions between mussel communities and their gut microbiomes structure these ecological processes across environments and geographic scales. Similarly, little is known about how host-microbiome interactions have structured the evolution of both groups over time. If the processes and mechanisms underlying patterns of biodiversity in these animals can be identified, managers will be better armed to make informed decisions for conservation and restoration efforts that will ultimately benefit the entire ecosystem. <br/><br/>Using approaches that scale from individual-to-population-to-species levels and above, this project seeks to understand ecological and evolutionary associations among the environment, genetic diversity, functional traits, and community assembly across both host and microbiome phylogenies in contemporary taxa and ancestral lineages. This research will integrate analyses of (1) intraspecific genetic diversity in a suite of freshwater mussel species, (2) phylogenetic diversity of communities of mussel species as well as their associated microbiomes, and (3) functional diversity of the mussel-microbiome holobiont. Integrating these three dimensions of biodiversity will allow us to comprehend the mechanisms that underpin the roles that freshwater mussels play in ecosystems, and to understand the fundamental ecological and evolutionary processes that structure biodiversity in space and over time. Furthermore, this work will extensively populate public databases with new data on species distributions, abundances, microhabitat environmental characteristics, and DNA sequence variation that will have impacts on basic evolutionary and ecology research while also informing conservation and management of a highly imperiled and ecologically important group.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.