Joan E. Strassmann, Ph.D.

Charles Rebstock Professor

Evolution, Ecology and Population Biology Program
Molecular Genetics and Genomics Program
Molecular Microbiology and Microbial Pathogenesis Program

  • 314-935-3527

  • 314-935-3505

  • 832-978-5961

  • 314-935-4432

  • 1137

  • Wilson 310

  • strassmann@WUSTL.EDU



  • social evolution; multicellularity; mutualism; symbiosis; experimental evolution; disease; social amoebae; Dictyostelium; science education; birds

  • We work on social interactions and mutualism using a microbial system so we can study cheating, conflict and cooperation at experimental and genomic levels, within and between species, in particular in social amoebae and their farmed bacteria

Research Abstract:

The evolution of life has resulted in the cooperative aggregation of cohesive units that prosper together. These units may be the same, as with the evolution of multicellularity, or they may be different, as with the evolution of the eukaryote cell. For such cooperation to evolve, conflicts at lower levels must be controlled. We study the evolution of cooperation and the control of conflict in a microbial eukaryote, the social amoeba Dictyostelium discoideum. It is uniquely suitable for this work because transitions that are fixed in most organisms are still flexible. This amoeba preys on bacteria but, when starved, aggregates into a multicellular body that moves towards light, and then differentiates into 20% dead stalk cells that support 80% living spore cells. When the multicellular stage is chimeric, the opportunity for one clone to cheat the other arises. We identify genes involved in this process, look at their rates of evolution using 20 resequenced clones and a handful of sequenced closely related species. We use experimental evolution to look at the robustness of the social process and the importance of high genetic relatedness within fruiting bodies in maintaining the altruistic caste. We explore kin recognition and its genetic basis. We study the evolution of development by constructing pseudo-organisms with artificial life cycles where we manipulate things like single-cell bottlenecks. We have found that some clones carry bacteria with them in a farming and defensive mutualism, and use this to experimentally study mutualism. In sum, our group studies what’s crucial to organismality.

Selected Publications:

Inglis, R. F., *Ryu, E., *Asikhia, O., Strassmann, J. E., & Queller, D. C. 2017. Does high relatedness promote cheater-free multicellularity in synthetic life cycles? Journal of Evolutionary Biology, DOI: 10.1111/jeb.13067

Douglas, T. E. Queller, D. C., & Strassmann, J. E. 2017. Social amoebae mating types do not invest unequally in sexual offspring. Journal of Evolutionary Biology DOI:10.1111/jeb.13056

Queller, D. C. & Strassmann, J. E. 2016. Problems of multi-species organisms: endosymbionts to holobionts. Biol Philos DOI 10.1007/s10539-016-9547-x.

Brock, D. A., *Callison, W. E, Strassmann, J. E., & Queller, D. C, 2016. Sentinel cells, symbiotic bacteria and toxin resistance in the social amoeba Dictyostelium discoideum. Proc. R. Soc B 283:2015272,

Ostrowski, E.A., Shen, Y., Tian, X., Sucgang, R., Jiang, H., Qu, J., Katoh-Kurasawa, M., Brock, D.A., Dinh, C., Lara-Garduno, F., Lee, S.L., Kovar, C.L., Dinh, H.H., Korchina, V., Jackson, L., Patil, S., Han, Y., Chaboub, L., Shaulsky, G., Muzny, D.M., Worley, K.C., Gibbs, R.A., Richards, S., Kuspa, A., Strassmann, J.E., and Queller, D.C. 2015. Genomic Signatures of Cooperation and Conflict in the Social Amoeba. Current Biology 25: 1661-1665.

DiSalvo, S., Haselkorn, T. S., Bashir, U., *Jimenez, D. A., Brock, D. A., Queller, D. C., Strassmann, J. E. 2015. Burkholderia bacteria infectiously induce the proto-farming symbiosis of Dictyostelium amoebae and food bacteria. Proc. Nat. Acad. Sci. USA 112 E5029 – E5037 doi: 10.1073/pnas.1511878112

Brock, D.A., Read, S., Bozhchenko, A., Queller, D.C. and Strassmann, J.E. (2013) Social amoeba farmers carry bacterial weapons to protect and privatize their crop. Nature Commumincations 4:2385 | DOI: 10.1038/ncomms3385

Stallforth, P. Brock, D. A., Cantley, A. M., Tian, X. Queller, D. C., Strassmann, J. E., Clardy, J. 2013. A bacterial symbiont is converted from an inedible producer of beneficial molecules into food by a single mutation in the gacA gene. Proc. Natl. Acad. Sci. USA 29:xxx-xxx, doi: 10.1073/pnas.1308199110

Seppa, P., Queller, D. C., Strassmann, J. E. 2012. Why wasp foundresses change nests: Relatedness, dominance, and nest quality. PLoS ONE, 7 e45386, doi:10.1371/journal.pone.0045386.

Queller, D. C. and Strassmann, J. E. 2012. Experimental evolution of multicellularity using microbial pseudo-organisms. Biology Letters doi10.1098/rsbl.2012.0636

Kuzdzal-Fick, J. J., Strassmann, J. E., & Queller, D. C. 2011. High relatedness is necessary and sufficient to maintain multicellularity in Dictyostelium. Science 334: 1548-1550. DOI: 10.1126/science.1213272.

Strassmann, J. E. & Queller, D. C. 2011. Evolution of cooperation and control of cheating in a social microbe. Proc. Natl. Acad. Sci. USA 108:10855-10862.

Last Updated: 12/18/2017 12:26:28 PM

Undergrads getting ready for our group photograph.
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