Evolutionary Biology

A graphical summary of my most recent paper

In July 2021, I joined the Peter Lind Group at the Department of Molecular Biology, Umeå University (Sweden) as a postdoctoral fellow supported generously by the Wenner-Gren Foundations. I'm currently attempting to develop approaches to forecast the evolution of antibiotic resistance in pathogenic bacteria by mapping mutation biases and fitness across diverse resistance mechanisms.

I'm a proud alumnus of the Population Biology Lab (PBL) at IISER Pune (India), where I spent more than a decade under the guidance of Sutirth Dey (I began as an undergrad trainee in 2010, continued as a PhD student, earned my doctorate in 2019, and worked as a postdoc until June 2021). During my time at PBL, I became fascinated by the interactions of mutation, drift and selection in organismal populations. I was (and still am) particularly captivated by the complexity that underlies the process of adaptation in seemingly simple asexual systems.


At PBL, I used combinations of bacterial experimental evolution, population-wide genomics, and agent-based simulations to study the following:

  • The effects of population size on adaptation and fitness trade-offs

  • The population genetics of divergent character evolution in identical environments

  • How and why the costs of adaptation are shaped by the interactions of population size and environmental fluctuations

Peer-reviewed publications

1. Chavhan, Y., Malusare, S. & Dey, S.

Interplay of population size and environmental fluctuations: A new explanation for fitness cost rarity in asexuals

Ecology Letters (2021) [doi.org: 10.1111/ele.13831]

Read-only full-text (PDF)



2. Chavhan, Y., Malusare, S. & Dey, S.

Larger bacterial populations evolve heavier fitness trade-offs and undergo greater ecological specialization.

Heredity 124, 726–736 (2020)
Full-text (downloadable PDF) |
Companion article

3. Chavhan, Y., Karve, S. & Dey, S.

Adapting in larger numbers can increase the vulnerability of Escherichia coli populations to environmental changes.

Evolution 73, 836–846 (2019)

Full-text link (final version on BioRxiv)

​4. Chavhan, Y., Ali, S. I. & Dey, S.

Larger numbers can impede adaptation in asexual populations despite entailing greater genetic variation.

Evolutionary Biology 46, 1–13 (2019)

Read-only full-text (PDF)

5. Karve, S., Daniel, S., Chavhan Y., Anand, A., Kharola, S.S.  & Dey, S.

Escherichia coli populations in unpredictably fluctuating environments evolve to face novel stresses through enhanced efflux activity.

Journal of Evolutionary Biology 28, 1131–1143 (2015)

Full-text link (downloadable PDF)

PhD Thesis

The Effects of Population Size on Adaptation and Trade-offs: Insights from Experimental Evolution with Escherichia coli and Individual-based Models

(Defended on September 6, 2019 under the supervision of Prof. Sutirth Dey at IISER Pune)

The May 2020 Heredity Podcast featuring my work

00:00 / 17:12

My talk at the Indo-Swiss Meeting on Evolutionary Biology (Dec 2019)

Yashraj Chavhan's talk at the Indo-Swiss meeting on Evolutionary Biology