RESEARCH
Geneticist
Nitin Phadnis Uncovering genomic conflicts to solve the ‘mystery of mysteries’ High-density housing in Nitin Phadnis’s lab: fruit flies live and breed in thousands of vials. Photo: Michael Schoenfeld
T
he first thing one notices on a tour of the Nitin Phadnis lab in the South Biology Building is the distinctive scent of cornmeal and molasses: room and board in thousands of plastic, numbered vials for the millions of fruit flies (Drosophila pseudoobscura) which are the subject of his research. Back in his office it’s more of a visual that you notice: a floor-toceiling white board with curious hieroglyphics at the bottom that look distinctively like that of child’s. These are not the markings of flies but of other small individuals. Phadnis is a father of a daughter and the white board has clearly been a tempting tabula rasa while visiting dad away from home … temptation with limited reach, at any rate.
Above these intriguing chicken scratches from tiny hands, there are formulas and graphs detailing the work of this geneticist who is asking, “how do new species evolve, anyway?” It’s a question that has driven his research since his arrival at the School of Biological Sciences in 2014 and is underscored by the energizing fact that the principles of biology, unlike mathematics and physics, are relatively young. “It’s been relatively recent that we even learned the structure of DNA,” Phadnis reminds you. “We didn’t have CRISPR gene-editing technologies or some of the advanced sequencing technologies even five years ago. There are a lot of unknowns still.” 10
Unknowns are what inspire this thirty-eight-year-old native of India who initially wanted to be an astrophysicist but found the questions in evolutionary genetics more interesting, and personally motivating. His lab attempts to answer questions about how new species arise and how silent but powerful evolutionary conflicts inside genomes drive cryptic changes. Speciation, the process by which one species splits into two, involves the evolution of reproductive isolating barriers such as the sterility or inviability (when an individual is unable to survive or develop normally) of hybrids between previously interbreeding populations. Cracking the code of how new species split from existing species hinges on understanding how and why such hybrids break down. Phadnis is quick to recall Darwin’s On The Origin of Species, in which the father of evolutionary science could find no satisfactory solution to the apparent paradox of why natural selection would tolerate the onset of these genetic barriers. Think of the mule: a cross between a horse and a donkey, but never able to sexually reproduce. The question of why mules and other hybrids are unfit has been pondered over since the days of Aristotle. Darwin called this problem the “mystery of mysteries.” Uncovering the molecular and evolutionary basis of speciation involves, first, the identification of genes that cause hybrid sterility
