What forces are driving speciation in the Porcini mushroom (Boletus edulis)?
Collaborators: Hoffman Lab (Bielefeld University); Brown Lab (University of Utah)
The porcini mushroom (Boletus edulis Bull.) is a globally distributed and prized edible mushroom species complex that has been variously split into numerous species and subspecies over time. Using whole genome sequencing of over 300 individuals we have shown that (1) Porcini is comprised of seven cryptic lineages which do not correspond with with previously characterized species, (2) all lineages are diverging in the face of on-going gene flow, but some lineages have more gene flow than others, and (3) that gene-flow between lineages is not limited by geography or substantial structural changes in the genome.
This project seeks to utilize the complex demographic landscape of the Porcini mushroom to elucidate the speciation process in Fungi. How do species form and what maintains species boundaries through time?
What are the evolutionary drivers of host preference in ectomycorrhizae?
Collaborators: PMI Consortium (Oak Ridge National Lab)
The genetic mechanisms that control interactions between plants and symbiotic fungi are poorly understood. Ectomycorrhizal fungi (EMF) are a highly diverse group of soil borne fungi (>20,000 species) that form mutualistic partnerships with ~8,000 species of plants. Previous work has shown that the genetic mechanisms of colonization are exceptionally diverse, and are likely host, EMF, or even habitat specific. Yet, we have identified select few of these pathways in even more select few EMF taxa, and currently have no understanding of the evolutionary or ecological mechanisms that drive their development. This projects seeks to disentangle this complex relationship by identifying the genetic pathways that are necessary for colonization, elucidating the mechanisms that drive the development of novel colonization mechanisms, and determine the role that host colonization plays in driving EMF diversification.
What are the macroevolutionary process that drive divergence over long evolutionary time?
To understand why Fungi are so diverse, we need to investigate the processes that allow for diversity to accumulate and persist over long evolutionary time. This project extends beyond single species systems to elucidate the macroevolutionary forces that drive diversification by identifying the genetic and ecological basis of a rapid evolutionary radiation in a family of EMF.
The porcini mushroom family Boletaceae is exceptionally diverse (>2000 currently accepted species), and ample evidence indicates that the family have undergone an evolutionary radiation 60-100 mya. Across this diverse family we have generated whole-genome sequences for over 400 new species (type specimens wherever possible, including specimens over 150 years old), and have used these genomes to construct the first fully resolved and robust phylogeny of the clade. We have also shown that the ancestor of the Boletaceae is likely Paleotropical in origin, separation of the Gondwanan supercontinent spurred diversification in some (but not all) groups within the family, and that speciation rates are greatest in high latitude temperate regions. Going forward, we are resequencing specimens with Oxford Nanopore sequencing to generate contiguous reference genomes to identify patterns of diversification in key ectomycorrhizal gene families on a long-evolutionary scale.
