Evolutionary Biology

A graphical summary of my most recent paper

In July 2021, I joined the Lind Lab at Umeå University (Sweden) as a postdoctoral fellow supported generously by the Wenner-Gren Foundation. I am currently working on two distinct projects:


1. To forecast the evolution of antibiotic resistance in pathogenic bacteria by empirically determining mutation biases across diverse resistance mechanisms and mapping them to their fitness effects [model organism: Pseudomonas aeruginosa]

2. To determine if phenotypic plasticity can prime bacteria for the evolution of a multicellular lifestyle [model organisms: Escherichia coli and Staphylococcus aureus]

I am an 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

Curriculum Vitae

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 24, 1943–1954 (2021)


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)
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)

​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)

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)

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