OOS 76-6
Fungal traits that drive ecosystem dynamics

Thursday, August 13, 2015: 3:20 PM
328, Baltimore Convention Center
Kathleen K. Treseder, Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA
Jay T. Lennon, Department of Biology, Indiana University, Bloomington, IN

Fungi contribute extensively to a wide range of ecosystem processes, including decomposition of organic carbon, deposition of recalcitrant carbon, and transformations of nitrogen and phosphorus. Moreover, fungal taxa vary in physiological and morphological traits that influence these processes, so environmentally-induced changes in fungal communities could create feedbacks on ecosystem function. We will address three unanswered questions related to this issue. First, how are ecosystem-related traits distributed among taxa and broad morphological groups (i.e., free-living filamentous fungi, yeasts, and mycorrhizal fungi)? Second, what suites of traits tend to co-occur within fungi? And third, what are the implications for trait-mediated feedbacks on ecosystem functions? We synthesized information from 157 published whole fungal genomes and determined relationships among selected functional genes within fungal taxa. 


Ecosystem-related traits varied most at relatively coarse taxonomic levels. For example, we found that the maximum amount of variance for traits associated with carbon mineralization, nitrogen and phosphorus cycling, and stress tolerance could be explained at the order- to phylum-levels. Moreover, suites of traits tended to co-occur within taxa. Specifically, the genetic capacities for traits that improve stress tolerance—β-glucan synthesis, trehalose production, and cold-induced RNA helicases—were positively related to one another, and they were more evident in yeasts. Traits that regulate decomposition of complex organic matter—lignin peroxidases, cellobiohydrolases, and crystalline cellulases—were also positively related, but were more strongly associated with free-living filamentous fungi. Altogether, these relationships provide evidence for two functional groups: stress tolerators, which may contribute to soil carbon accumulation via the production of recalcitrant compounds; and decomposers, which may reduce soil carbon stocks. It is possible that ecosystem functions such as soil carbon storage may be mediated by shifts in the fungal community between stress tolerators and decomposers in response to environmental changes like drought and warming.