|Wednesday, July 07|
Bryan is an evolutionary biologist and studies Sphagnum peat mosses. His research integrates techniques in experimental ecology, computational biology, and phylogenetics to better understand how genetic variation across levels of biological organization correlates with variation in plant functional traits that scale to drive ecosystem processes. Bryan received a Ph.D. in Biology from Duke University in 2020 (advisor: Jon Shaw), a master's degree from Southern Illinois University in 2015 (advisor: Karen Renzaglia), and a bachelor's degree from Roanoke College in 2012 (advisor: DorothyBelle Poli). He currently works on evolutionary genomics in Sphagnum as a Postdoctoral Associate at Duke University.
From genes to traits and ecosystems: reconstructing the evolution of extended phenotypes in Sphagnum (peat moss)
* Bryan Piatkowski, Duke University, United States
Plants in the genus Sphagnum (peat moss) are the dominant biotic features of boreal peatlands that store roughly one-quarter of Earth’s terrestrial carbon. Peat mosses are ecosystem engineers and create the peatlands that they inhabit through the accumulation of peat, or partially decayed biomass, and the functional traits underlying this extended phenotype. Interspecific trait variation promotes niche differentiation through the creation of ecological gradients along which species sort within communities. One prominent gradient relates to height-above-water-table wherein some species produce hummocks elevated above the water table, while others live in hollows at or near the water table. However, it is unclear how these traits evolved during Sphagnum diversification, to what extent natural selection produced functional trait variation, and which genes might contribute to such phenotypes. I sought to better understand how genes can scale to ecosystems through plant functional traits using Sphagnum as a model system. Meta-analysis was used to demonstrate that variation in traits related to growth, decomposability, and litter biochemistry is phylogenetically conserved in Sphagnum, suggesting a genetic basis for these traits. Using field experiments, I found that selection favors different levels of decomposability corresponding to optimum niche. Genomic data were then used to show that genes involved in cell wall biosynthesis are related to decomposability and were among the targets of selection during the evolution of hummock and hollow lineages. These results demonstrate evolution of ecosystem engineering via selection on an extended phenotype, of a fundamental ecosystem process, and one of the Earth’s largest soil carbon pools.