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Harvard Forest REU Symposium Abstract 2023
- Title: Effects of a Warming Temperature on Microbial Evolution
- Author: Gena Ligon Blumencwejg (Colorado College)
- Abstract:
Climate change presents a significant environmental challenge, impacting global ecosystems and influencing evolution. Microbes play a vital role in ecosystem function and carbon cycling, making them important for predicting climate change impacts. To comprehend the effect of long-term warming on microbial evolution, understanding microbial communities' response is crucial. However, the effects of long-term warming on microbial communities remains unclear. We hypothesize that taxa in heated plots will grow more slowly when incubated at 15°C and 25°C due to limited microbial substrate availability, and that the temperature sensitivity of growth(Q10) rate will show evidence of adaptation to long-term warming. Data from a 2020 quantitative stable isotope probing (qSIP) experiment(in which isotopes are incorporated into bacterial samples) using soils from Harvard Forest long-term warming plots are utilized to investigate these hypotheses. The experiment includes long-term warming, soil type, and 4 field replicates (incubated at 15°C or 25°C with 16O or 18O water), resulting in 64 samples with 8 density fractions each for a total of 512 samples. QIIME 2 is used to detect OTUs (operational taxonomic units, assigned at 99% sequence identity) in heated and control samples and to construct a phylogenetic tree. OTUs are then used to calculate the excess atom fraction (EAF)(which is how the incorporation of the isotope tracer is expressed) of each taxon and the EAF of plots on average (EAF25/EAF15). EAF is then mapped at the corresponding branch tips to account for phylogeny. Blomberg's K and Pagel’s lambda tests are used to assess phylogenetic signals of EAF and the change in EAF. To investigate the second hypothesis, the temperature sensitivity of growth (Q10), is calculated for individual taxa through separate and combined OTU analyses. We expect to find that in warmed plots, the overall growth rates will be slower than control plots. We also expect that Q10 is phylogenetically conserved, and that Q10 will be greater in heated than control plots. These results will help in predicting and mitigating climate change effects.
- Research Category: Biodiversity Studies
