School of Physics Thesis Dissertation Defense

Presenter:          Thomas Day

Title:                     Biophysical Constraints of Multicellularity: Building a Darwinian Material

Date/Time:         Wednesday, February 22, 2023 at 1:30 p.m.

Location:             EBB Seminar Room 1005 (Children's Healthcare of Atlanta Seminar Room)

Virtual Link:       https://gatech.zoom.us/j/99213799612?pwd=LytLVVFQTW4ranRiL2RWUXhZV1F1dz09

Meeting ID: 992 1379 9612 / Passcode: 422625

Committee:       Dr. Peter Yunker, School of Physics, Georgia Institute of Technology (advisor)

Dr. Jennifer Curtis School of Physics, Georgia Institute of Technology

Dr. Harold Kim, School of Physics, Georgia Institute of Technology

Dr. William Ratcliff, School of Biological Sciences, Georgia Institute of Technology

Dr. Kurt Wiesenfeld School of Physics, Georgia Institute of Technology

Abstract: The evolution of multicellularity fundamentally changed life on Earth, resulting in successful and impactful lineages that continue to permeate and change the planet. Yet its origins, usually buried in the deep past, have remained unclear. For example, it is unknown how multicellular traits arise and emerge as repeatable and heritable. It is also unclear how spatial patterns of cell differentiation arise from undifferentiated origins. However, there is a growing understanding that physical considerations play an outstanding role in shaping incipient multicellularity. Here, we use this biophysical viewpoint to investigate how physical constraints arise in freshly multicellular groups, and how these constraints may enable or limit subsequent adaptation and evolution. We show, through a combination of experiments, simulations, and theory, that some properties of multicellularity, that are historically considered difficult to achieve, can freely emerge without needing group-level genes. We suggest that by considering more biophysical challenges for nascent multicellularity, we may yet find solutions to problems that were previously considered unsolvable.