Dimensions of Biodiversity

NSF Dimensions of Biodiversity Project

Project #1542639:

Dimensions: Collaborative Research: Biodiversity Gradients in Obligate Symbiotic Organisms: A Case Study in Lichens in a Global Diversity Hotspot

University of Colorado Participants:
Erin Tripp

Nolan Kane

Christy McCain

New York Botanical Garden Participant:
James Lendemer

Project Summary:

Obligate symbioses are relationships between two or more species that depend entirely on each other for growth and survival. Such symbioses characterize some of the most common and ecologically important relationships on Earth, ranging from human gut bacteria to diseases to corals to specialized plant-pollinator relationships. Many of these obligate symbioses are imperiled by unprecedented rates of environmental change and permanent biodiversity losses. Compared to single branches on the tree of life such as birds, flowering plants, or mammals, much less is known about factors that facilitate or limit the geographical distributions of obligate symbioses that abound in nature. Moreover, research on biodiversity distributions has focused largely on abiotic factors (e.g., temperature, precipitation, elevation) rather than on biotic factors (i.e., other organisms) that influence geographical distributions. This project aims to transform understanding of factors that impact diversity and distributions of obligate symbiotic biodiversity through investigation of lichens as a model system in a unique natural laboratory and global lichen diversity hotspot: the southern Appalachian Mountains.

Proposed mechanisms for factors that generate and maintain biodiversity remain contentious despite decades of research. Biotic factors have long been proposed as drivers but are rarely studied due to the difficulty of assessing the multitude of possible interactions. Because of the inherent biotic interaction that exists between obligate symbionts, this project will explore both biotic and abiotic drivers of biodiversity across multiple dimensions. Through field and genomic inventories of lichens in a biodiversity hotspot, this project will generate and investigate data from symbiotic biodiversity initiated from a single information source: a unique museum voucher. Across local, regional, and landscape scales, inventories will yield site-specific metrics for phylogenetic (including taxonomic) and functional diversity together with site-specific metrics for a mostly unexplored genetic dimension—potential of diversity—that quantifies the availability of compatible symbiont propagules in the environment. Analyses of these metrics in light of biotic and abiotic variables will enable assessment of factors that impact overall dimensions of biodiversity. These analyses will also permit understanding of interactions among dimensions, for example, whether phylogenetic, functional, and genetic dimensions are positively correlated and predicted by the same sets of variables, or in what contexts other types of correlations exist. This project will yield two major conceptual advances in ecology and evolutionary biology. First, information gained will likely reveal new, emergent properties of biodiversity gradients in symbiotic organisms. Second, deconstructing constraints on individual partners of the symbiosis and quantifying feedbacks between/among them will make possible full analysis (i.e., including biotic constraints) of the factors that impact diversity and distribution of the symbiotic organism as a whole.

Broader impacts of this research will improve scientific literacy, expand awareness of symbiotic biodiversity, build capacity in U.S. lichenology, broaden collaborations between scientists and land managers, and establish new ‘big data’ resources for a diverse audience of researchers and educators. Finally, this project will advance conservation of an ecologically important group of understudied organisms in a premier biodiversity hotspot.


Diversity and distributions of obligate symbiotic organisms: lichens as a model system for deconstructing biotic and abiotic factors that drive major patterns in macroecology and macroevolution.

Recent publications or news items related to the project

  • PIs Lendemer and Tripp publish a new species of lichen endemic to high elevation, nutrient-rich rocks of the Southern Appalachians (Lendemer & Tripp [2015], The Bryologist 118: 1-10: Lecanora anakeestiicola (Lecanorales): an unusual new fruticose species from Great Smoky Mountains National Park in eastern North America
  • Co-PI Kane is currently training undergraduate and graduate students to assemble lichen mycobiont and photobiont genomes during his Genomics course at the University of Colorado
  • PIs Tripp and Lendemer are currently in the process of recruiting PhD students to advance aspects of the Dimensions research;
  • Co-PI McCain is spearheading the development of the field inventory sampling strategy; fieldwork will begin in early 2016.
  • PIs Lendemer and Tripp are collaborating with the Center for Biological Diversity to assess the federal conservation status of ~30 rare and mostly endemic southern Appalachian lichens