Soil fungi release up to three-fold more carbon dioxide (CO2) to the atmosphere than human activity through the decomposition of dead organic matter (i.e. litter) in soil. Ecologists have frequently observed a pattern of fungal community assembly during litter decomposition, wherein different fungal taxa dominate different stages of decay in individual ecosystems. However, we still lack a complete understanding of how these diverse fungal communities generate decomposition. My dissertation helps to fill this knowledge gap by elucidating the cross-ecosystem taxonomic patterns of fungal decomposer succession and identifying biological features that correlate with these lineage-specific patterns.
I conducted a meta-analysis of fungal decomposer succession in 22 ecosystems to identify the taxonomic patterns that were consistent across ecosystems and test environmental correlates of those patterns. I found a phylogenetic signal to succession and observed that the relative abundance of Ascomycetes was negatively correlated with observed peak decay stage, the relative abundance of Zygomycetes was positively correlated with peak decay stage, and the relative abundance of Basidiomycetes remained relatively constant throughout decay. I also found that plant litter type and climate factors were correlates of peak decay stage. Next, I performed laboratory culture experiments to test two longstanding hypotheses: that innate potential activity of plant cell wall-degrading enzymes and intrinsic growth rate underlie organisms’ peak decay stage. I found that potential cellulase activity and growth rate correlated negatively with peak decay stage and that growth rate explained more than a third of the phylogenetic signal to peak decay stage. Finally, I completed a comparative genomics study of fungi that have different observed decay stages. I found that protein domains related to plant C-degrading enzymes and growth-related biochemical pathways are part of the biology that underlies the succession of fungi and that transcriptional regulation and stress response may also underlie succession.
This dissertation generates novel insights into the biology that underlies fungal decomposer community turnover during plant litter decay. This work provides direction for future research into the drivers of the assembly of decomposer communities and has important implications for efforts to incorporate fungal biology into predictive models of decomposition and terrestrial C-cycle dynamics.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/43968 |
| Date | 05 March 2022 |
| Creators | Vivelo, Alexandra |
| Contributors | Bhatnagar, Jennifer M. |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution-NonCommercial-NoDerivatives 4.0 International, http://creativecommons.org/licenses/by-nc-nd/4.0/ |
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