{"660134":{"#nid":"660134","#data":{"type":"event","title":"PhD Defense by Pedro Marquez Zacarias ","body":[{"value":"\u003Cp\u003EIn partial fulfillment of the requirements for the degree of Doctor of Philosophy in Quantitative\u0026nbsp;\u003Cbr \/\u003E\r\nBiosciences\u003Cbr \/\u003E\r\nin the School of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EPedro Marquez Zacarias\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDefends his thesis:\u003Cbr \/\u003E\r\nTitle: Life cycles and nascent multicellularity\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWednesday, August 17, 2022 3:30pm Eastern Time\u003Cbr \/\u003E\r\nhttps:\/\/gatech.zoom.us\/j\/97899556958 Open to the Community\u003Cbr \/\u003E\r\nAdvisor:\u003Cbr \/\u003E\r\nWilliam Ratcliff (School of Biological Sciences, Georgia Tech)\u003Cbr \/\u003E\r\nCommittee Members:\u003Cbr \/\u003E\r\nPeter Yunker (School of Physics, Georgia Tech)\u003Cbr \/\u003E\r\nSamuel Brown (School of Biological Sciences, Georgia Tech)\u003Cbr \/\u003E\r\nEric Smith (Earth-Life Science Institute at Tokyo Tech, and Santa Fe Institute) David Murrugarra\u0026nbsp;\u003Cbr \/\u003E\r\n(Department of Mathematics, University of Kentucky)\u003Cbr \/\u003E\r\nAbstract:\u003Cbr \/\u003E\r\nLife is organized hierarchically. From cells to societies, the levels of biological organization\u0026nbsp;\u003Cbr \/\u003E\r\nshape evolutionary trajectories. These hierarchies are traditionally studied through the lens of\u0026nbsp;\u003Cbr \/\u003E\r\nthe Major Evolutionary Transitions (MET) framework. One such major transition is the evolution of\u0026nbsp;\u003Cbr \/\u003E\r\nmulticellularity, which gave rise to the evolution of complex life forms like animals, plants, and\u0026nbsp;\u003Cbr \/\u003E\r\nfungi.\u003Cbr \/\u003E\r\nFirst, I will discuss how multicellular organisms differ in their ecology and evolutionary\u0026nbsp;\u003Cbr \/\u003E\r\ntrajectories, particularly depending on whether they develop via aggregation (cells coming\u0026nbsp;\u003Cbr \/\u003E\r\ntogether) or by clonal development (cells staying together). This will lead up to a more general\u0026nbsp;\u003Cbr \/\u003E\r\nquestion about life cycles, and how are these organized differently in multicellular organisms\u0026nbsp;\u003Cbr \/\u003E\r\ncompared to their unicellular counterparts. To give clarity on this matter, I developed a\u0026nbsp;\u003Cbr \/\u003E\r\ncompositional algebra to serve as a formal language to represent and analyze life cycles of\u0026nbsp;\u003Cbr \/\u003E\r\narbitrary complexity. With this algebra, I was able to describe the life cycles of complex and\u0026nbsp;\u003Cbr \/\u003E\r\nsimple multicellular organisms and found that organisms that develop via aggregation are more\u0026nbsp;\u003Cbr \/\u003E\r\nsimilar to unicellular organisms than even simple multicellular organisms. I provide some criteria\u0026nbsp;\u003Cbr \/\u003E\r\nto distinguish between hierarchical levels of reproduction, which I\u003Cbr \/\u003E\r\ndistinguish from the levels in MET by the features of their life cycles.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThen, I present a simple model of clonal multicellular development that explicitly accounts for\u0026nbsp;\u003Cbr \/\u003E\r\nspatial constraints. In this model, cells have a specific pattern of cell division that can account\u0026nbsp;\u003Cbr \/\u003E\r\nfor simple morphological features observed in nascent multicellular organisms. Using this model, I\u0026nbsp;\u003Cbr \/\u003E\r\nwas able to directly query the effects of aspect ratio and lateral cell growth, or \u0026lsquo;side-budding\u0026rsquo;.\u0026nbsp;\u003Cbr \/\u003E\r\nThese are two traits known to be important for organismal size in snowflake yeast, which is the\u0026nbsp;\u003Cbr \/\u003E\r\nexperimental system we use in the lab to study multicellular evolution. Further, I show how simple\u0026nbsp;\u003Cbr \/\u003E\r\ngenetic disruptions to the machinery that controls the patterns of growth in single cell yeast can\u0026nbsp;\u003Cbr \/\u003E\r\nhave important effects when applied to snowflake yeast.\u003Cbr \/\u003E\r\nFinally, I present a novel method to measure spatial structure in biofilms, which leverages methods\u0026nbsp;\u003Cbr \/\u003E\r\nand concepts from network theory. This method relies on the network representation of a biofilm,\u0026nbsp;\u003Cbr \/\u003E\r\nwhich gives us flexibility and scalability while preserving as much detail as needed. I show how\u0026nbsp;\u003Cbr \/\u003E\r\nthis method is applied to real data, by analyzing microbial communities with cooperative or\u0026nbsp;\u003Cbr \/\u003E\r\ncompetitive interactions, and showing the detailed spatial information recovered with the proposed\u0026nbsp;\u003Cbr \/\u003E\r\nmethod.\u003Cbr \/\u003E\r\nAltogether, in my thesis work I explored the theme of biological organization: the organization of\u0026nbsp;\u003Cbr \/\u003E\r\nlife cycles, the morphological organization of simple multicellularity, and the spatial\u0026nbsp;\u003Cbr \/\u003E\r\norganization of\u003Cbr \/\u003E\r\nmicrobial communities.\u003Cbr \/\u003E\r\n\u0026nbsp;\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Life cycles and nascent multicellularity"}],"uid":"27707","created_gmt":"2022-08-15 13:27:03","changed_gmt":"2022-08-15 13:27:03","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2022-08-17T16:30:00-04:00","event_time_end":"2022-08-17T18:30:00-04:00","event_time_end_last":"2022-08-17T18:30:00-04:00","gmt_time_start":"2022-08-17 20:30:00","gmt_time_end":"2022-08-17 22:30:00","gmt_time_end_last":"2022-08-17 22:30:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78771","name":"Public"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}