Unraveling patterns of natural variation in an ecologically significant mutualism: species delimination and diversity in west coast mycorrhizal fungi

点击翻译按钮获取中文摘要

Trees, in order to flourish, must be associated with symbiotic mycorrhizal fungi. Climate change models predict that ranges of tree species will change dramatically over the next years. Will their fungal partners be able to keep pace with the changes? Our project will help answer this question by providing a systematic framework of the patterns of genetic diversity in Cortinarius, Inocybe, and Russula, three of the most widespread and species rich fungal genera from Canada's west coast. Our previous environmental sampling highlighted astonishing gaps in our understanding of the diversity of these fungi. Most detected species were unrepresented in fungal collections and their sequences were absent from GenBank. Yet, if frequency of occurrence in nature is any guide, these same fungi are major players in our ecosystems. We are building the fungal collections in the UBC herbarium/Beaty museum to serve as a repository of information about species diversity and to provide the materials for our studies. This is possible thanks to enthusiastic donations from undergraduate students, local experts, and 'amateur' mycologists. Through such donations, we tripled UBC's holdings of Cortinarius specimens in the past year. So that we can recognize groups of closely related specimens, we are screening UBC specimens using DNA sequences from the standard fungal reference region: the ribosomal internal transcribed spacer (ITS). For species that are represented by enough specimens (after including newly donated UBC specimens, new field collections made by my students, and specimens from other herbaria) we will delimit species using six additional genetic loci. After careful delimitation of species, we will investigate fungal population subdivisions and migration rates from northern BC through Oregon and Washington. Low effective population sizes, narrow geographical ranges and limited diversity may flag species that are unlikely to survive climate change. Alternatively, large effective population sizes and evidence of rapid postglacial migration would provide an encouraging indication that individual fungal species are likely to accompany the migration of tree species, allowing the retention of this important mutualistic symbiosis.