Abstract:
Microbiomes mediate a variety of important ecosystem functions. However,it remains unclear what attributes of the microbiome are important for determining
the rate of ecosystem functions. Past attempts to elucidate this relationship
have either looked too broadly at microbiome diversity or have assumed a priori
that we know which taxa are limiting to the rate of function. To overcome this
challenge, I borrowed strategies from population genetics including association
mapping and artificial selection to robustly identify microbial markers of ecosystem
function. I observed high heritability of methane oxidation rate in soil microbiomes
demonstrating that variation in the microbial community can generate variation in
ecosystem function independent of the environment. In addition, I characterized
soil metagenomes along a land-use change gradient with increasing methane
emissions. By looking agnostically across all microbial metabolic pathways, I
identifed a surprising relationship between the relative abundance of nitrogen
fixation genes and the rate of methane emissions. Using this conceptual framework
to investigate biodiversity-ecosystem function relationships will deepen our
understanding of microbiome function for ecosystem services and human health.
This dissertation includes previously published co-authored material.