NSF Postdoctoral Fellowship in Biology: The Eco-Evolutionary Tradeoffs of Aggregative Multicellularity

Stoy Kayla, Mableton GA

Investigators

Abstract

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2022, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment and Phenotypes. The fellowship supports research and training of the Fellow that will contribute to the area of Rules of Life in innovative ways. This research will advance understanding of how complex life has evolved. Many living organisms, including plants and animals, depend on cooperative interactions between many cells that carry out specific and important functions. These complex organisms are referred to as multicellular. In contrast, other organisms have remained unicellular and do not depend on cooperative cellular interactions to persist. Previous research suggests complex multicellularity has not evolved for some organisms because cells choose to act selfishly rather than cooperate with one another. The conditions that favor and inhibit the evolution and persistence of cooperative multicellular interactions remains an outstanding question in the field of evolutionary biology. This research will address this knowledge gap by determining the conditions under which more complex organisms evolve. Addressing this question is important to improving our understanding of how multicellular life arose on Earth, and why there is so much variation in multicellular complexity across the tree of life. The Fellow will mentor students from underrepresented groups in research as well as through public outreach activities. This research will test the hypothesis that integration in aggregative multicellular organisms is limited by an eco-evolutionary trade-off: unstable environments favor social generalism, which limits the evolution of genotype-specific multicellular integration. The research will use synthetic biology to generate a laboratory model system of aggregative multicellularity, engineering the yeast Saccharomyces cerevisiae to require obligate metabolic cross-feeding. Aggregative yeast will be experimentally coevolved to examine how the fidelity of their mutualistic partners affects the evolution of genotype-genotype specialization. The ecological implications of specialization will then be assessed by testing for fitness tradeoffs associated with specialists and generalists. These results will be placed in a broader context by using a theoretical model to evaluate the effect of environmental heterogeneity on the evolution of multicellularity. The Fellow predicts that increased complexity will evolve when there are increased opportunities for specialization between coevolved cells. Fellow training includes metabolomics, microscopy, and mathematical modeling at Georgia Tech. The Fellow will also broaden participation in science by mentoring first-generation and low-income undergraduates in scientific research and by developing hands-on scientific activities for underrepresented elementary school students. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.