Toward a Global Phylogeny of the Boletales

 The Boletales is a monophyletic order of homobasidiomycetes (Fungi) that includes approximately 1025 described species that are distributed worldwide. The Boletales are diverse in both morphology and ecology. Fruiting bodies in the group include stipitate-pileate forms (those with a stalk and cap), crust-like resupinate forms, earthballs, and false truffles. Members of the Boletales obtain carbon nutrition by entering into ectomycorrhizal symbioses or by decaying wood, and a few are suspected to be mycoparasites. Some are highly prized edibles; others are important food sources for mammals, and many are rearing sites for insects.

            The Boletales have been widely studied by fungal systematists, chemists, ecologists, and mycorrhizal biologists. However, investigations in all these areas have been hampered by the lack of a comprehensive phylogenetic classification for the group. For example, poor resolution of the basal clades of Boletales makes it difficult to infer the ancestral form of the group; lack of understanding of generic boundaries makes it difficult to assess relationships of newly discovered species; and ambiguous species limits within many clades are a barrier to ecology and biodiversity studies.

We propose to perform an intensive molecular phylogenetic study across all major groups of the Boletales. The proposed research involves two nested subprojects:

1. A multi-gene analysis using exemplars of all major groups of Boletales and representatives of potential outgroups in the homobasidiomycetes. We will analyze a dataset of six loci (nuc-ssu, nuc-lsu, atp6, RPB1, RPB2, EF-1a) of 52 species from the major clades of Boletales, as well as potential outgroup taxa. The goals of these studies are to provide a “backbone” phylogeny and resolve the major clades of Boletales.

2. A survey of diverse Boletales, using nuclear large-subunit rDNA and ITS sequences. We will analyze an extensive data set of nuc-lsu rDNA and ITS sequences of approximately 700 species from all continents except Antarctica, with an emphasis on North American, European, and neotropical material. The goals of these studies are to develop a broad phylogenetic framework for the Boletales; provide resources for species-level taxonomy and molecular ecology; and understand the evolution of nutritional modes, fruiting body forms, and other characters.

Outreach activities in this project will take two forms:

1. We will create a series of pages in the Tree of Life Web Project for each of the major groups of Boletales. These pages will bring information about the diversity and ecology of Boletales to a broad audience, including students and educators.

2. We will design and implement a four-week learning module on "Molecular Ecology and Systematics of Mycorrhizal Fungi" for high school students, in collaboration with Minuteman Regional High School (Lexington, MA). This module will engage students in a discovery-based research project that demonstrates the integration of molecular biology, organismal biology, and bioinformatics.


Intellectual merit of the proposed activity:

This project will contribute to a phylogenetic classification of a large, ecologically important clade of fungi. Well-sampled phylogenetic trees will permit analyses of the evolution of fruiting body forms and other taxonomically important characters, as well as transitions between symbiotic and free-living lifestyles.

Broader impacts resulting from the proposed activity:  

This project will provide resources for fungal molecular ecologists (specifically ITS sequences in GenBank) and systematists, and will promote the discovery of new species of Boletales. There are currently several ongoing projects in Boletales, but these are either regional in scope, or limited to specific genera. The proposed research will provide a comparative database that can be used to integrate the results of disparate studies in Boletales and contribute to a global classification of the group. The Tree of Life web pages will provide resources for students and educators. The four-week module in “molecular ecology and systematics of ectomycorrhizal basidiomycetes” for high school students will raise awareness about fungal biology specifically, and molecular approaches to problems in ecology and evolutionary biology. It will also forge ties between a private liberal arts university (Clark University) and a public high school (Minuteman Regional High School).

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