- Postdoctoral Fellow, Developmental Biology, Max Planck Institute, 2010-2014
- Ph.D., University of California, Riverside, 2009
Assistant Professor, Biology
Assistant Professor, Biology
Myers Hall 100
Ragsdale Lab website
Alexander von Humboldt Fellowship, 2011-2013
Erasmus Mundus Scholar, 2010
My research focuses on the role of developmental mechanisms in the evolution and diversification of form, using nematode worms as a tractable laboratory model. Nematodes lead virtually every lifestyle known to animals and include microbivores, omnivores, predators, and parasites of insects, vertebrates, and plants. The diversity of nematode mouthparts bears testament to this remarkable ability to specialize. I seek to unravel the mechanisms underlying such morphological diversification by integrating developmental biology, genetics, population genetics, phylogenetics, and natural history.
My lab uses the nematode Pristionchus pacificus as a reference point and model, and we focus on the genetic basis of developmental plasticity (polyphenism) in its mouthparts. After an irreversible decision in larval development, nematodes of this species, and others in its family (Diplogastridae), assume one of two distinct feeding-forms that perform alternative ecological functions. This dimorphism involves an evolutionary novelty: teeth, which enable predatory feeding on other nematodes.
Given the sometimes drastic influence environment has on phenotypes, it is possible that developmental plasticity also plays a role in the evolution of such phenotypes, including novel traits. To question this possibility, my lab studies mouth plasticity in nematodes to identify the genetic program for executing a morphological novelty, and we are testing the significance of such a program in the evolution of plastic traits.
A few goals of this research include:
Specifically, my lab is using forward genetics to reconstruct the genetic pathway for a polyphenism switch and revealing how this switch has appeared and changed across lineages. Furthermore, we are using inference-based and reverse genetics approaches to understand the evolution of "plasticity genes" and their targets. In summary, my lab combines developmental genetics with comparative and phylogenetic approaches to understand the mechanisms and evolution of developmental responses to the environment.
Ledón-Rettig, C.C., Moczek, A.P., and Ragsdale, E.J. (2018). Diplogastrellus nematodes are sexually transmitted mutualists that alter the bacterial and fungal communities of their beetle host. PNAS 115: 10696–10701.
Bui, L.T., Ivers, N.A., and Ragsdale, E.J. (2018). A sulfotransferase dosage-dependently regulates mouthpart polyphenism in the nematode Pristionchus pacificus. Nature Communications 9: 4119.
Projecto-Garcia, J., Biddle, J. F., and Ragsdale, E. J. (2017). Decoding the architecture and origins of mechanisms for developmental polyphenism. Current Opinion in Genetics & Development 47: 1-8.
Ragsdale, E. J. and Ivers, N. A. (2016). Specialization of a polyphenism switch gene following serial duplications in Pristionchus nematodes. Evolution 70: 2155-2166.
Kieninger, M. R., Ivers, N. A., Rödelsperger, C., Markov, G. V., Sommer, R. J., and Ragsdale, E. J. (2016). The nuclear hormone receptor NHR-40 acts downstream of the sulfatase EUD-1 as part of a developmental plasticity switch in Pristionchus. Current Biology 26: 1-6.