An Integrated View of Metazoan Evolution
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University of Akron / OhioLINK
2015
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ndltd-OhioLink-oai-etd.ohiolink.edu-akron14379588652021-08-03T06:32:21Z An Integrated View of Metazoan Evolution Wain, Ashley R. Biology Ecology Evolution and Development Geology Paleontology Multicellularity Metazoa Experimental Evolution Choanoflagellates Serotonin Plasiticity Evolution Macroevolution 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 2015-09-10 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1437958865 http://rave.ohiolink.edu/etdc/view?acc_num=akron1437958865 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Biology Ecology Evolution and Development Geology Paleontology Multicellularity Metazoa Experimental Evolution Choanoflagellates Serotonin Plasiticity Evolution Macroevolution |
| spellingShingle |
Biology Ecology Evolution and Development Geology Paleontology Multicellularity Metazoa Experimental Evolution Choanoflagellates Serotonin Plasiticity Evolution Macroevolution Wain, Ashley R. An Integrated View of Metazoan Evolution |
| author |
Wain, Ashley R. |
| author_facet |
Wain, Ashley R. |
| author_sort |
Wain, Ashley R. |
| title |
An Integrated View of Metazoan Evolution |
| title_short |
An Integrated View of Metazoan Evolution |
| title_full |
An Integrated View of Metazoan Evolution |
| title_fullStr |
An Integrated View of Metazoan Evolution |
| title_full_unstemmed |
An Integrated View of Metazoan Evolution |
| title_sort |
integrated view of metazoan evolution |
| publisher |
University of Akron / OhioLINK |
| publishDate |
2015 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=akron1437958865 |
| work_keys_str_mv |
AT wainashleyr anintegratedviewofmetazoanevolution AT wainashleyr integratedviewofmetazoanevolution |
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1719438574468726784 |