Biography
I received my B.A. in Computer Science and Earth and Planetary Sciences from Johns Hopkins University in 2003 and a Ph.D. in Earth and Planetary Sciences from Harvard University in 2009. After two years as an O K Earl Postdoctoral Scholar in Geology and Postdoctoral Scholar in Geobiology at Caltech, I joined Haverford College in 2011 to contribute to the Environmental Studies and Biology programs. I have served as the Director (chair) of the Environmental Studies Program at Haverford and led the team that developed the new Bi-College Environmental Studies Major and Department. In the spring of 2018, I was promoted to Associate Professor with tenure, and in the summer of 2018 my position was converted to be dedicated to the Environmental Studies Department. I enjoy field-based work, whether geological or botanical in nature, and try to spend my summers near some combination of plants, rocks, and trout.
Research
My lab investigates the coevolution of plants and the environment over the last 475 million years. We employ mathematical models, chemical analysis of fossils, comparative anatomy, and experimental plant physiology to reanimate extinct plants, focusing on examples with unusual anatomy, development, or growth forms. These insights shed light on past (and future) climate change, the evolutionary trajectory of plant adaptations, and ecosystem responses to mass extinctions. You can download my papers here.
Active research areas
Physiological properties of extinct plants
The major ongoing project in my lab is employing a series of mathematical models to calculate fluid dynamics properties of plant tissues based upon measurements of cells within their water transport system, the xylem. These mathematical models and statistical relationships take as their inputs various dimensions of xylem cells, including cell width, length, and porosity, and the outputs are hydraulic conductivity and resistance to damage from water stress. Taken together, conductivity and stress resistance allow extinct plants to be categorized and quantified physiologically: some plants have high hydraulic conductivity but low resistance to damage from water stress, whereas others are the reverse. The focus of this project has been to identify trends and patterns in plant physiological evolution in the time since the evolution of water transport tissue in plants, approximately 410 million years ago. My work has been able to identify extinct plant groups that employed hydraulic strategies that are absent from terrestrial ecosystems today, including physiologies that are comparatively risky, where high transport rates come at the cost of reduced safety from drought stress damage. The focus of this project has been to identify trends and patterns in plant physiological evolution in the time since the evolution of water transport tissue in plants, approximately 410 million years ago. My work has been able to identify extinct plant groups that employed hydraulic strategies that are absent from terrestrial ecosystems today, including physiologies that are comparatively risky, where high transport rates come at the cost of reduced safety from drought stress damage.
Paleoenvironmental insights from extinct plants
Plants are exceptional among multicellular organisms because aspects of their anatomy and morphology record environmental information. Furthermore, the biogeographic distribution of plants today—and in deep time—is shaped by environmental constraints. Applying a variety of modeling techniques to different organs of extinct plants, including roots, stems, and leaves, yields a quantitative picture of how extinct plants responded to, and shaped, Earth surface feedbacks. Data generated by Haverford College undergraduates and our collaborators has demonstrated that Pennsylvanian SubPeriod forests contained a broader spectrum of plant physiological strategies than previously thought, including plants capable of extreme drought resistance and others that could support high transpiration rates. Secular change among these plant communities during the Pennsylvanian likely exerted profound changes on planetary feedbacks, terrestrial environments, and elemental fluxes during the Late Paleozoic Ice Age.
Evolution of plant biomineralization and the terrestrial silica cycle
The global carbon cycle is tied to a variety of other elemental cycles on the surface of the Earth, including the cycle of silicon. Today, approximately 50% of all photosynthetic activity is conducted by diatoms, small marine algae that build shells out of silicon, and these microscopic algae are responsible for converting carbon dioxide into organic carbon that sinks to the bottom of the ocean, reducing the concentration of CO2 in the atmosphere. Silicon is a necessary nutrient for these diatoms, and it is supplied to the ocean by plant tissues: certain plants accumulate silicon in their organs from soils and rocks they grow upon, and when these plants die, their leaves, stems, and roots decay and silicon flows to the ocean, fertilizing diatoms. Our preliminary work has shown that silicon accumulation is not distributed in a uniform way throughout all land plants—some accumulate substantial silicon (and thus supply much silicon to the ocean) whereas others accumulate very little. Specifically, our preliminary work has shown that a number of ancient land plant lineages, particularly ferns, accumulate more silicon than any other living plant group, and also that many of these lineages have been ecologically important for more than four hundred million years. Our ongoing work has been to clone, sequence, and identify the genes that code for these novel silicon transporters in these early-diverging land plant lineages. A major portion of these results was published in the Proceedings of the National Academy of Sciences in March, 2015.
Microbial diversity on leaves (the “phyllosphere”)
As part of an ongoing series of Superlab courses, we have been investigating the physiological and phylogenetic diversity of bacteria found on leaves. This microbial community has been called the “phyllosphere” and contains approximately as much bacterial diversity as the human gut. Students collected leaves from trees and plants across the Haverford campus and extracted DNA from the bacteria on leaves, using both culture-independent methods (extracting DNA directly from bacteria physically separated from the leaves using sonication) and culture-dependent methods (growing organisms from the leaves and isolating them in pure culture). Bacterial samples are identified using 16S rRNA sequencing, and students have identified a number of unusual organisms, including some that are new species. Ongoing work is focused on the abundance and diversity of rare bacteria on conifer leaves and intercontinental variation in phyllosphere diversity.
Multiple origins of leaves
Using a similar approach as the silicon transporter project, we are working to clone and sequence PIN1, one of the genes responsible for leaf and vascular development, in Equisetum, Psilotum, and Botrychium. Each of these lineages diverged from ferns via a set of leafless ancestors between 375 and 300 million years ago and independently acquired—and perhaps one evolved and then lost—leaves. PIN1 plays a key role in leaf initiation and leaf vein formation, but very little is known about its function in spore-bearing plants that have leaves; our project is aimed at shedding light on this early stage in the evolution of leaves. If we are successful in these efforts, we hope to learn whether the multiple origins of leaves early in the vascular plant lineages that led to modern ferns always occurred in the same fashion.
Extinct plant biomechanics
As a postdoc at Caltech, I developed a rapid, semi-destructive technique for determining the lignin content of fossil plant tissues using geochemical analysis, which, in turn, helps constrain the biomechanical properties of extinct plant tissues. The lignin biosynthetic pathway includes a step that contains an isotopic fractionation, where an enzyme preferentially incorporates the light stable isotope of carbon (12C) over the heavy stable isotope of carbon (13C), and measuring the relative abundance of these two isotopes against one another, called the stable carbon isotope composition (δ13C), can help distinguish between heavily lignified and lightly lignified tissue. By measuring unambiguously lignified tissue from fossil plants, such as plant xylem, and differentiating it from tissues of unknown biochemical composition, such as the external or cortical tissues in the same fossil, we can construct a map of the biomechanical properties of different tissues within the same plant fossil. If the cortical tissues are lignified, and are therefore contributing to the biomechanical stability of the plant, they will have a chemical signature more closely resembling xylem; if they are unlignified, and have values substantially different from those found within the xylem, they are unlikely to have played a role in the structural support of the plant. This project was published inInternational Journal of Plant Sciences in 2011.
Water/carbon tradeoffs in early vascular plants
One of the most interesting subfields of plant physiology (with serious implications for the study of past ecosystems) has been linking plant anatomical traits to physiological properties. A number of studies have shown that key parameters, including photosynthetic rate and leaf hydraulic capacity, are determined and controlled by the morphology and arrangement of plant vascular tissues and apertures on leaves, called stomata. The most interesting of these studies have shown that these relationships are quantitatively robust across all clades of vascular plants; that is, a fern, conifer, and angiosperm leaf that all happen to have the same vein density and distribution and size of stomata would all have similar photosynthetic rates, despite the great evolutionary distance between them. The implications for the study of extinct plants are vast: plant physiological traits in leaves can therefore be reconstructed quantitatively from leaf anatomy alone.
Past projects
Life in a low-oxygen world: geobiology of the ~1.8 billion year old Duck Creek Dolomite, Western Australia
Several years ago, we investigated the geochemical, sedimentological, mineralogical, and stratigraphic context for a deposit of iron-coated bacteria from the Duck Creek Dolomite, a ~1.8 billion year old carbonate platform. By measuring the stable carbon and oxygen isotope composition of these rocks (at 2-meter intervals over >1km of section) and localizing the microbiota within their mineralogical and paleoenvironmental distribution, we were able to demonstrate that the Duck Creek Dolomite preserves a unique geobiological window into the low-oxygen world following the evolution of oxygenic photosynthesis. This project was published in Precambrian Research in 2010.
Paleoenvironmental distribution of early animal burrows: Treptichnus pedum in Namibia
With this project, we were able to demonstrate that Treptichnus pedum, the trace fossil that marks the global transition from the Ediacaran Period to the Cambrian Period, can be found in high abundance in a relatively narrow paleoenvironmental window within incised valley deposits in southern Namibia. This project was published in Palaios in 2012.
Recent and forthcoming publications
- Jonathan P. Wilson, Isabel P. Montañez, Joseph D. White, William A. DiMichele, Jennifer C. McElwain, Christopher J. Poulsen, Michael T. Hren (2017). Dynamic Carboniferous tropical forests: new views of plant function and potential for physiological forcing of climate. New Phytologist, v. 215(4) p. 1333–1353.
- Isabel P. Montañez, Jennifer C. McElwain, Christopher J. Poulsen, Joseph D. White, William A. DiMichele, Jonathan P. Wilson, Galen Griggs, Michael T. Hren (2016). Linked shifts in glacial–interglacial CO2, climate, and terrestrial carbon cycling during Earth's last icehouse. Nature Geoscience, v. 9 p. 824–828.
- Highlighted in: Timothy S. Myers (2016). Palaeoclimate: CO2 and late Palaeozoic glaciation. Nature Geoscience, v. 9 p. 803–804.
- Jonathan P. Wilson (2016). Evolutionary trends in hydraulic conductivity after land plant terrestrialization: from Psilophyton to the present. Review of Palaeobotany and Palynology, v. 227 p. 65–76.
- Jarmila Pittermann, Jonathan P. Wilson, Timothy J. Brodribb (2016). Plant water transport and clade diversification: examples from extinct and extant taxa. Encyclopedia of Evolutionary Biology, v. 4 p. 358–366.
- Jennifer C. McElwain, Isabel P. Montañez, Joseph D. White, Jonathan P. Wilson, Charilaos Yiotis (2016). Was atmospheric CO2 capped at 1000 p.p.m. over the past 300 million years? Palaeogeography, Palaeoclimatology, Palaeoecology, v. 444 (4), p. 653–658. Doi: 10.1016/j.palaeo.2015.10.017
- Jonathan P. Wilson, Joseph D. White, Jennifer C. McElwain, William DiMichele, Christopher Poulsen, Michael Hren, Isabel P. Montañez (2015). Reconstructing extinct plant water use for understanding vegetation-climate feedbacks: methods, synthesis, and a case study using the Paleozoic Era medullosan seed ferns. Paleontological Society Papers, v. 21 p. 167-195.
- Elizabeth Trembath-Reichert, Jonathan P. Wilson, Shawn E. McGlynn, Woodward W. Fischer (2015). 400 million years of silica biomineralization in land plants. Proceedings of the National Academy of Sciences, v. 112 (17) 5449-5454. Doi: 10.1073/pnas.1500289112
- Highlighted in: Daniel J. Conley and Joanna C. Carey (2015). Silica cycling in geologic time. Nature Geoscience, v. 8 431-432.
- Jonathan P. Wilson (2013). Modeling 400 million years of plant hydraulics. Paleontological Society Papers, v. 19 p. 1–20.
- A. Hope Jahren, Brian A. Schubert, Leszek Marynowski and Jonathan P. Wilson (2013). The carbon isotope organic geochemistry of Early Ordovician rocks from the Annascaul Formation, County Kerry. Irish Journal of Earth Sciences, v. 31 p. 1–12.
- Taylor S. Feild and Jonathan P. Wilson (2012). Evolutionary voyage of the angiosperm vessel: comparative xylem hydraulic innovation and its significance for early angiosperm success. International Journal of Plant Sciences, v. 173 p. 596–609.
- Jonathan P. Wilson and 11 others (2012). Deep-water incised valley deposits at the Ediacaran-Cambrian boundary in southern Namibia contain abundant Treptichnus pedum. Palaios, v. 27(4) p. 252–273.
- Jonathan P. Wilson and Woodward W. Fischer (2011). Geochemical support for a climbing habit within the Paleozoic seed fern genus Medullosa. International Journal of Plant Sciences, v. 172(4) p. 586–598.
- Jonathan P. Wilson and Woodward W. Fischer (2011). Hydraulics of Asteroxylon mackei, an early Devonian vascular plant, and the early evolution of water transport tissue in terrestrial plants. Geobiology, v. 9 p. 121–130.
Teaching
I teach a broad range of classes at all levels of the curriculum, from introductory courses to supervised research. In 2018, I was recognized by Haverford for excellence in teaching and was given the Lindback Distinguished Teaching Award, awarded to one faculty member every other year.
Here are brief summaries of my courses, listed from the introductory level to advanced courses:
- Environmental Studies 101 ("Case Studies in Environmental Issues"): A case-studies-based, co-taught, multidisciplinary approach to the study of the environment. Case studies have included climate, coal, natural gas, water, extreme weather, and more. Taught every year.
- Biology 201 (Introduction to Molecular Biology): The introductory course in the molecular biology sequence. Topics include phylogenetics, biochemistry, evolutionary biology, and biophysics, with an emphasis on plants as a case study.
- Biology 300/301 (Third-year Lab): The third-year “superlab” course in molecular biology. Investigation of the plant microbiome using molecular, ecological, and environmental tools.
- Biology 314 ("Photosynthesis"): A half-semester course on the biochemistry and evolution of photosynthesis, from its origin in the ocean more than 2.5 billion years ago to the fate of Earth’s vegetation in response to climate change. Taught frequently.
- Biology 318 and 118 ("Economic Botany" and "Plants and People"): A joint majors (Biology 318) and nonmajors (Biology 118) course on plant biology, physiology, evolution, and biodiversity through the lens of economically important plants. Taught every year.
- Environmental Studies 397 (Environmental Studies Senior Capstone): The capstone experience for Environmental Studies students. Supervised, applied, and project-based.
- Environmental Studies/Biology 413 (Senior Research): Senior research in my lab. Focused on research questions at the intersection of plant biology and evolution.