{"647168":{"#nid":"647168","#data":{"type":"event","title":"PhD Defense by Seyed Alireza Zamani Dahaj","body":[{"value":"\u003Cp\u003EIn partial fulfillment of the requirements for the degree of\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDoctor of Philosophy in Quantitative Biosciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003Ein the School of Physics\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ESeyed Alireza Zamani Dahaj\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nDefends his thesis:\u003Cbr \/\u003E\r\n\u003Cstrong\u003EDe novo evolution of macroscopic multicellularity and trait heritability in major transitions.\u003C\/strong\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cbr \/\u003E\r\nTuesday, May 4, 2021\u003Cbr \/\u003E\r\n3:00pm Eastern Time\u003Cbr \/\u003E\r\nVia BlueJeans: \u003Ca href=\u0022https:\/\/bluejeans.com\/917049243\u0022\u003Ehttps:\/\/bluejeans.com\/917049243\u003C\/a\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EAdvisor:\u003C\/p\u003E\r\n\r\n\u003Cp\u003EProf. Peter J. Yunker\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Physics\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ECo-Advisor:\u003Cbr \/\u003E\r\nProf. William C. Ratcliff\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cbr \/\u003E\r\nCommittee Members:\u003Cbr \/\u003E\r\nProf. Daniel B. Weissman\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDepartment of Physics\u003C\/p\u003E\r\n\r\n\u003Cp\u003EEmory University\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EProf. Raphael F. Rosenzweig\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EProf. Joshua S. Weitz\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EAbstract:\u003C\/p\u003E\r\n\r\n\u003Cp\u003EEvolutionary Transitions in Individuality (ETIs) describe the history of the increasing complexity of life and the emergence of hierarchical organization in an elegant framework.\u0026nbsp; Each transition is characterized by a group of independent individuals coming together and forming a group that eventually can undergo Darwinian evolution and turns into a new individual level. One of the prominent examples of ETIs is the emergence of multicellularity. In this thesis, I address two key questions about the transition to multicellularity: \u0026nbsp;The emergence of heritability of higher-level traits and its relationship to cell-level traits. First, I discuss how the heritability of newly-formed group traits emerges as groups emerge. \u0026nbsp; We introduce a simple theoretical model for calculating group-level trait heritability, where the trait is the linear function of a cell-level trait. \u0026nbsp;For cases in which the relationship is more complex than a linear function, we developed a statistical simulation to model and explore different kinds of analytical functions based on biological examples of relationship between cell-level traits and collective-level traits. \u0026nbsp;Finally, using the snowflake yeast model system we did an experiment that shows an ecologically relevant, emergent trait in a nascent multicellular organism can have a higher heritability across a range of conditions than the unicellular-level trait on which it is based. The evolution of complex multicellularity presents an apparent paradox: nascent multicellular organisms are thought to require (relatively) large size to evolve complex traits, but at the same time maintaining large size requires complex organization at the cell and group levels. This poses a chicken and egg problem between large size and cellular development. Here, we show that over the course of a year snowflake yeast can increase its size multiple orders of magnitude with minimal change at the cell level by taking advantage of the physical properties of granular entangled materials. \u0026nbsp;These results suggest that in the same way that physically imposed geometric constraints can limit the size of clusters, an-other innovations can lead to the emergence of a new biophysical mechanism that changes the\u0026nbsp;material properties of the clusters.\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"De novo evolution of macroscopic multicellularity and trait heritability in major transitions. "}],"uid":"27707","created_gmt":"2021-05-04 19:52:18","changed_gmt":"2021-05-04 19:52:18","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2021-05-04T16:00:00-04:00","event_time_end":"2021-05-04T18:00:00-04:00","event_time_end_last":"2021-05-04T18:00:00-04:00","gmt_time_start":"2021-05-04 20:00:00","gmt_time_end":"2021-05-04 22:00:00","gmt_time_end_last":"2021-05-04 22:00:00","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":[],"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":""}}}