Greetings!  I am an evolutionary biologist who uses evolution experiments with bacteria to examine a variety of fundamental questions. My foremost interest is in the role of history in evolution. Unlike most natural phenomena, evolution involves a complex interaction between chance and necessity that makes it subject to what is called "contingency". Essentially, this means that evolving lineages of organisms will experience unique histories, and those histories can affect how they evolve. Contingency affects evolutionary repeatability, so we need to understand its effects if we are to fully understand or predict evolution. I am interested in how contingency affects, among other things, speciation, the origin, evolution, and consequences of novel traits, evolutionary potential, and the origins of biodiversity. Most of my work is focused on a population of E. coli that evolved to grow aerobically on citrate during the Long-term Evolution Experiment, which has studied the evolution of twelve, initially identical populations of E. coli in the lab for more than 75,000 generations since it began on February 24, 1988. This system provides me with a highly flexible model with which I can investigate contingency (and much more) because it lets me directly access and study its evolutionary history, not to mention manipulate it to examine how evolution would have gone under counterfactual "what if" scenarios. 
The LTEE was recently featured in a video produced by the YouTube science channel, Veritasium! Thank you to Derek Muller for bringing the LTEE to a larger audience, and for all his hard work in advancing science communication!
Veritasium: The Longest-Running Evolution Experiment 

I was a guest on the Knowledge Archives podcast:
November 27, 2020 Episode: Evolutionary Contingency: Does History Repeat Itself?

Most recent publications:  
Evolution of a Cross-feeding Interaction Following a Key Innovation in a Long-Term Evolution Experiment with Escherichia coli. Turner CB, Blount ZD, Mitchell DH, Lenski RE. Microbiology, 169:001390. https://doi.org/10.1099/mic.0.001390

Genotypic and Phenotypic Evolution of Escherichia coli in a Novel Citrate-Only Resource Environment
Blount ZD, Maddamsetti R, Grant NA, Ahmed ST, Jagdish T, Baxter JA, Sommerfeld BA, Tillman A, Moore J, Slonczewski JL, Barrick JE, Lenski RE. 

Jagdish T, Morris JJ, Wade BD, Blount ZD. Probing the Deep Genetic Basis of a Novel Trait in Escherichia coli. Pp. 107 – 122 in Banshaf W, Cheng B, Deb K, Holekamp K, Lenski R, Ofria C, Pennock R, Punch B, Whittaker D (eds). Evolution in Action: Past, Present, and Future. New York, NY: Springer Nature. 2020.
August 31, 2023: Microbiology just published a paper spearheaded by my wonderful colleague, Caroline Turner (now of Loyolla University, Chicago), which details the nifty cross-feeding interaction that evolved between the Cit- lineage of cells that persisted in the Ara-3 population after aerobic growth on citrate evolved and the Cit+ cells that stems from the unusual physiology of the transporter used to acquire citrate from the medium. The interaction is an excellent example of how evolutionary innovations can have unexpected consequences owing to their jury-rigged natures. After all, evolution doesn't build new traits and functions from scratch, but more often than not by repurposing old materials lying around in the proverbial genomic junk drawer left by past evolution. The resulting novelties work, but with knock on effects that have important consequences. Read it for yourself: Evolution of a cross-feeding interaction following a key innovation in a long-term evolution experiment with Escherichia coli 
July 26, 2023:  My great mentees, Claire "Spends" Spender and Max Halliday, had their first poster session today. They presented on work they have been helping me that goes into how the fitness value of access to different resources is changing in the Cit+ lineage as it is ecologically diverging from its ancestor and undergoing incipient speciation. They have helped to show that the Cit+ lineage is gaining fitness on both citrate, a resource the lineage discovered, and C4-dicarboxylates, a resource it creates itself as a byproduct of growth on citrate, while also losing fitness on glucose. They did an excellent job in this first outing, reflecting their altogether great work in the lab!
The members of Biol 191: Not Just Darwin, Fall 2018
Back: Shara Morgan, Adam Brown, Maleah Miller, Emma Wolfe Raible, Miles Crawford
Middle: Eli Rocke, Dylan Manning, Jane Zisman, Ana Inciardi
Front: Kate Zibas, Me, Schuyler Stupica, Sutton Amthor, Jess Karan
During my first semester as a visiting professor at Kenyon college, I got my first opportunity to develop my own course. I called it "Not Just Darwin". The idea was to cover the history of the idea of evolution as it morphed and changed through history, bloomed into a full theory with Darwin, went through a turbulent adolescence during the Eclipse of Darwinism, to emerge into vigorous adulthood with the Modern Synthesis and subsequent developments. The course also dipped into topics like the misuse of evolutionary theory for odious ideas like Social Darwinism, eugenics, and scientific racism and sexism, as well as the essentials of human evolution before wrapping up with a unit on the flavors and developments of creationism. It ended up being a spectacularly fun course that let me indulge my interests in not only science, but also philosophy and history. I learned a great deal, and generally had the best teaching experience of my life - indeed one of my best life experiences thus far. Much of this owes to the wonderful, brilliant, enthusiastic, and talented students I was fortunate enough to have in the class, not a one of whom was a biology major. They allowed me to experiment and grow as the class went on, indulged me in my tangents, and forgave me my mistakes. I am a better teacher because of them. I can only hope that they learned as much from me as I did from them. Take note of their names, for they will make the future.
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