The Evolution of Cell Cycle Regulation, Cellular Differentiation, and Sexual Traits during the Evolution of Multicellularity

Persistent Link:
http://hdl.handle.net/10150/626165
Title:
The Evolution of Cell Cycle Regulation, Cellular Differentiation, and Sexual Traits during the Evolution of Multicellularity
Author:
Hanschen, Erik Richard
Issue Date:
2017
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
During the evolution of multicellularity from unicellular ancestors, cells transition from being evolutionary individuals to components of more complex, multicellular evolutionary individuals. The volvocine green algae provide a powerful model system for understanding the genetic and morphological changes that underlie and are caused by the evolution of multicellularity. This dissertation concerns the role of cell cycle regulation, cellular differentiation, and sexual traits during the evolution of multicellularity. While some of these are shown to be causally important in the origins of multicellularity (Appendix B), others are driven by the evolution of multicellularity (Appendix D). We provide a review of recent mathematical models on the evolution of multicellularity, which are found to focus heavily on the later, subsequent stages of the evolution of multicellular complexity. We found that many of these models assume multicellular ancestors and instead evolve cellular differentiation, bringing attention to a gap in our understanding of the events in the initial stages of the evolution of multicellularity. We show that a focus on the early stages of the evolution of multicellularity reveals a powerful and critical role for regulation of the cell cycle at the origins of multicellularity (Appendix B). We further find that the genetic basis for cellular differentiation evolved sometime after the evolution of cell cycle regulation. We find that while the genetic basis for cellular differentiation evolved after cell cycle regulation, it also evolved earlier than previously predicted in the volvocine green algae, suggesting an important role in undifferentiated species (Appendix C). Lastly, having elucidated the origins and evolution of multicellularity, we find that multicellularity causes the evolution of sexual traits including anisogamy, internal fertilization, and subsequently sexual dimorphism (Appendix D). This work emphasizes the important role that multicellularity plays in driving the evolution of sexual diversity seen across the eukaryotic tree and well as informs critical hypotheses on the evolution of anisogamous sex, among the most challenging problems in evolutionary theory.
Type:
text; Electronic Dissertation
Keywords:
anisogamy; genomics; green algae; multicellularity; sex; volvocine
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Ecology & Evolutionary Biology
Degree Grantor:
University of Arizona
Advisor:
Michod, Richard E.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleThe Evolution of Cell Cycle Regulation, Cellular Differentiation, and Sexual Traits during the Evolution of Multicellularityen_US
dc.creatorHanschen, Erik Richarden
dc.contributor.authorHanschen, Erik Richarden
dc.date.issued2017-
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.abstractDuring the evolution of multicellularity from unicellular ancestors, cells transition from being evolutionary individuals to components of more complex, multicellular evolutionary individuals. The volvocine green algae provide a powerful model system for understanding the genetic and morphological changes that underlie and are caused by the evolution of multicellularity. This dissertation concerns the role of cell cycle regulation, cellular differentiation, and sexual traits during the evolution of multicellularity. While some of these are shown to be causally important in the origins of multicellularity (Appendix B), others are driven by the evolution of multicellularity (Appendix D). We provide a review of recent mathematical models on the evolution of multicellularity, which are found to focus heavily on the later, subsequent stages of the evolution of multicellular complexity. We found that many of these models assume multicellular ancestors and instead evolve cellular differentiation, bringing attention to a gap in our understanding of the events in the initial stages of the evolution of multicellularity. We show that a focus on the early stages of the evolution of multicellularity reveals a powerful and critical role for regulation of the cell cycle at the origins of multicellularity (Appendix B). We further find that the genetic basis for cellular differentiation evolved sometime after the evolution of cell cycle regulation. We find that while the genetic basis for cellular differentiation evolved after cell cycle regulation, it also evolved earlier than previously predicted in the volvocine green algae, suggesting an important role in undifferentiated species (Appendix C). Lastly, having elucidated the origins and evolution of multicellularity, we find that multicellularity causes the evolution of sexual traits including anisogamy, internal fertilization, and subsequently sexual dimorphism (Appendix D). This work emphasizes the important role that multicellularity plays in driving the evolution of sexual diversity seen across the eukaryotic tree and well as informs critical hypotheses on the evolution of anisogamous sex, among the most challenging problems in evolutionary theory.en
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectanisogamyen
dc.subjectgenomicsen
dc.subjectgreen algaeen
dc.subjectmulticellularityen
dc.subjectsexen
dc.subjectvolvocineen
thesis.degree.namePh.D.en
thesis.degree.leveldoctoralen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineEcology & Evolutionary Biologyen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorMichod, Richard E.en
dc.contributor.committeememberMichod, Richard E.en
dc.contributor.committeememberBarker, Michaelen
dc.contributor.committeememberFerrières, Régisen
dc.contributor.committeememberOlson, Bradley J. S. C.en
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