Overview. Fungi inhabit most of the worlds ecological niches where they perform numerous services that are central to ecosystem functioning (e.g., nutrient cycling, foundations of food webs, etc.). They comprise the most successful and diverse phyla of eukaryotic microbes, interacting with all other forms of life in associations that range from beneficial (e.g., mycorrhizae) to antagonistic (e.g., pathogens). Despite significant advancements in our understanding of the evolutionary relationships within the fungal Kingdom (= Fungi), the earliest diverging lineages are still very poorly understood. Included among these are those involving important evolutionary transitions in growth and reproductive forms that ultimately culminated in the emergence of the Dikarya, i.e., Ascomycota and Basidiomycota. Overall, resolving the earliest branches in the fungal genealogy is essential to identify the characteristics of the ancestral fungi, to determine what traits emerged with the dawn of terrestrial ecosystems, and to obtain an accurate assessment of the morphological and genetic homologies that comprise and culminate in the fungal life style. Central to this transition are zygomycetous fungi. Intellectual Merit. Zygomycetes are filamentous, nonflagellated fungi that mark the major transition away from zoosporic life histories of the universal common ancestors of Fungi and the earliest diverging lineages of Chytridiomycota and Blastocladiomycota (the chytrids) and the rise of the nonflagellated, filamentous, multicellular Dikarya. Their phylogenetic relationship to other fungi is poorly understood, but essential to understanding the evolution of fungi through the transition of flagellum loss. An initial analysis zygomycete genomes support the group being a transition point between the origin of Fungi as flagellated taxa with limited thallus differentiation, i.e., the chytrids, and what became the dominant eukaryotic terrestrial clade of Fungi in the emergence of the Dikarya. Because the zygomycetes are the first terrestrial fungi with fruiting bodies, understanding how these structures evolved should provide a basis for understanding the origins of complex morphologenesis in the Fungi. By gathering orders of magnitude more genome-scale data and integrating it with biochemical, morphological, subcellular, and fossil data, we will accurately reconstruct this elusive region of the fungal genealogy of life. The specific aims and experimental plan are designed to test the following major hypotheses: H1: Genealogical reconstruction of the zygomycetes is complicated by ancient divergence times and complex patterns of gene duplication and loss that obscure patterns of homology. H2: Zygomycetes are an important transitional point in Fungi and the plant-associated ecologies of the MMG clade correlate with the establishment of terrestrial plant based ecosystems. H3: The filamentous body plan of zygomycetes represents the signature innovation of fungal evolutionary transitions that lead to the dominant fungal phenotype, the mycelium. H4: Mating genetics, communication between nuclei and life cycles within zygomycetes are fundamentally different from the Dikarya Broader Impacts. Zygomycetes are ubiquitous fungi with roles in many aspects of society: from fermentation of foodstuffs, to improving crop yields through mycorrhizae, to causes of human mycoses. Therefore, maintaining the expertise on these fungi is critical for the field of biology as well as the health of our population. This project has multiple avenues by which the impacts of the research will be broadened to society: training of the next generation of mycologists, dissemination of information on the basic biology and development of teaching resources for the public through EOL webpages and expansion of the zygomycetes.org website, development of research materials for the wider scientific community, and broadening of participation of underrepresented groups in STEM disciplines.
|Effective start/end date||10/3/14 → 12/31/18|
- NSF-BIO: Division of Environmental Biology (DEB): $468,743.00