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An Integrated View of Metazoan Evolution

Wain, Ashley R.
http://rave.ohiolink.edu/etdc/view?acc_num=akron1437958865

Abstract Details

2015, Doctor of Philosophy, University of Akron, Integrated Bioscience.
Complexity of organisms is ultimately dependent upon the number of cells present within an organism. Single-celled organisms are arguably the least complex of all living things with complexity increasing as cells are gained. The first major step in this process was achieving coloniality. The choanoflagellate species, Salpingoeca rosetta, used primarily in this study has a colonial life stage. Following that, organisms transitioned to true multicellularity with cell specialization being one of the requirements for that distinction. This transition, from colonial to multicellular animal life, is the topic of investigation in this dissertation. Multicellular animals evolved ~700 million years ago in the late Proterozoic, 1.4 billion years after the evolution of the eukaryotic cell. Investigations into the transition typically cite at least one of three major causes of the end to stasis in the animal lineage: Nursall's "Oxygen Control Hypothesis", the evolution of macrophagous predation, and changes in the chemical environment. Without direct fossilized evidence recorded and because the metazoan ancestor cannot be studied directly, a close relative, Salpingoeca rosetta was used in neontological tests of the roles of dissolved oxygen, predation, and the presence of serotonin, an ancient signaling molecule, in multicellular development. This is the first study to include long term experimental evolution of choanoflagellates to investigate the impacts of environment on the transition to multicellularity in animals. The combined evidence from the following studies indicates that the transition may have been brought about by a combination of the factors with a strong dependence on the common ancestor of unicellular and multicellular animals being pre-adapted for multicellular life. Genes for cell adhesion and intercellular communication are two of those pre-adaptations possessed by a close relative of the common ancestor, the choanoflagellates. Both were included in the following investigations and responded to experimental manipulation of environments to test the impacts of abiotic and ecological changes thought to have led to the evolution of multicellular animal
Francisco Moore (Advisor)
Richard Londraville (Committee Member)
Stephen Weeks (Committee Member)
Tom Leeper (Committee Member)
Joel Duff (Committee Member)
Lisa Park (Committee Member)
188 p.
Biology; Ecology; Evolution and Development; Geology; Paleontology
Multicellularity; Metazoa; Experimental Evolution; Choanoflagellates; Serotonin; Plasiticity; Evolution; Macroevolution

Recommended Citations

Citations

  • Wain, A. R. (2015). An Integrated View of Metazoan Evolution [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1437958865

    APA Style (7th edition)

  • Wain, Ashley. An Integrated View of Metazoan Evolution. 2015. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1437958865.

    MLA Style (8th edition)

  • Wain, Ashley. "An Integrated View of Metazoan Evolution." Doctoral dissertation, University of Akron, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1437958865

    Chicago Manual of Style (17th edition)

akron1437958865
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This open access ETD is published by University of Akron and OhioLINK.