Arjuna rajakumar
ph.d. student (year 2)


I joined the Abouheif lab in June 2014. Upon completing an MSc focusing on cancer signaling biology, I welcomed the change to the lush, exciting and eternally fascinating world of ecological evolutionary developmental biology; Eco-Evo-Devo. This field is concerned with how genes and the environment interact during development to shape evolutionary processes. I could immediately relate to this; in the three years I had spent studying cancer signaling pathways, I would best describe a tumor cell as a perfect Darwinian model. In response to a multitude of environmental cues and developmental reprogramming, the tumor cell is capable of surviving, adapting, persisting and thriving in its new microenvironmental niche to proliferate and metastasize; survival of the fittest in the truest sense of the word.

My PhD work in the lab will operate within the framework of Eco-Evo-Devo to charter an important question in biology; how genes interact with their social environment during organismal development, and how this interaction affects social evolution. In this respect, I will use ants as a tool to study this interplay; as they have evolved highly organized societies. A key feature of their social organization is the reproductive division of labor within a single colony, where queens reproduce while workers perform most other tasks. This remarkable cooperation carries with it a potential conflict between queens and workers – the workers of most ant species have retained ovaries that can produce male eggs. This conflict occurs when workers selfishly reproduce instead of performing their tasks.

I will be building upon a previous discovery of the Abouheif lab of an adaptive molecular mechanism called “Reproductive Constraint,” which reduces this potential conflict by preventing workers from producing viable male eggs. During queen oogenesis, maternal determinants (mRNAs and proteins) are deposited into the oocyte and localize to the posterior pole, resulting in viable eggs. In contrast, during worker oogenesis, these maternal determinants do not localize properly in a large proportion of oocytes resulting in a large proportion of defective male eggs. Therefore, Reproductive Constraint, which has been found in all species tested, has evolved to reduce the conflict between queens and workers over male-production.

The proximate goal of my research will be to uncover the behavioral and molecular mechanisms underlying Reproductive Constraints in workers, while my ultimate goal will be to examine the interplay between the evolution of Reproductive Constraint and social evolution; particularly the role Reproductive Constraint may have played in the evolution of larger complex ant societies.