Persistent Link:
http://hdl.handle.net/10150/578719
Title:
Evolution Of Arthropod Morphological Diversity
Author:
Pace, Ryan M.
Issue Date:
2015
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:
A fundamental problem in developmental and evolutionary biology is understanding the developmental genetic basis of morphological diversity. The current paradigm holds that a genetic and developmental program, or developmental genetic "toolkit", conserved across hundreds of millions of years patterns development in all metazoans. However, outside of a few well-characterized signal transduction pathways and developmental processes, overly broad strokes have been used to paint this "toolkit" metaphor as a hypothesis. Arthropoda, one of the largest groups of metazoans, represent the most morphologically diverse groups of metazoans, making them of particular interest for studies of morphological diversity and its evolution. Arthropoda is also home to one of the most well-understood model systems for developmental and genetic studies, the fruit fly Drosophila melanogaster. However, Drosophila is highly derived among arthropods with respect to the molecular genetic mechanisms that function during its development. As it is expected that all arthropods have access to the same development "toolkit", some changes are expected based on the observable differences in morphology, making arthropods extremely powerful tools for comparative genomic and molecular genetic studies. In this dissertation I characterize how modifications to the developmental "toolkit" contribute to the evolution of morphological diversity using emerging model arthropod systems. First, as part of a collaboration, I show that several genes expected to be conserved in all arthropods, belonging to the Hox family of transcription factors, have been lost from the genome of a phylogenetically basal arthropod, the two-spotted spider mite Tetranychus urticae. Second, I perform a genomic survey and find an overall reduction in the conservation of Drosophila orthologs from several major signal transduction pathways in the Tetranychus genome in comparison with findings from previous insect surveys. Third, I show that arthropod Hox genes, expected to be found in a tightly linked genomic cluster in most arthropod genomes, are not as tightly clustered as previously thought. Fourth, I show that changes in the genomic arrangement of Tetranychus Hox genes correspond with shifts in their expression and morphological change. Finally, I show the terminal Hox gene Abdominal-B is required for proper axial elongation and segment formation (both segment identity and number) during embryogenesis and metamorphosis in the red-flour beetle Tribolium castaneum. Taken together, these findings advance our knowledge of the evolution of morphological change, with a primary focus on Hox genes and their contribution to axial patterning during development.
Type:
text; Electronic Dissertation
Keywords:
development; evolution; Hox genes; morphological diversity; signal transduction; Molecular & Cellular Biology; arthropod
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Molecular & Cellular Biology
Degree Grantor:
University of Arizona
Advisor:
Nagy, Lisa M.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleEvolution Of Arthropod Morphological Diversityen_US
dc.creatorPace, Ryan M.en
dc.contributor.authorPace, Ryan M.en
dc.date.issued2015en
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.abstractA fundamental problem in developmental and evolutionary biology is understanding the developmental genetic basis of morphological diversity. The current paradigm holds that a genetic and developmental program, or developmental genetic "toolkit", conserved across hundreds of millions of years patterns development in all metazoans. However, outside of a few well-characterized signal transduction pathways and developmental processes, overly broad strokes have been used to paint this "toolkit" metaphor as a hypothesis. Arthropoda, one of the largest groups of metazoans, represent the most morphologically diverse groups of metazoans, making them of particular interest for studies of morphological diversity and its evolution. Arthropoda is also home to one of the most well-understood model systems for developmental and genetic studies, the fruit fly Drosophila melanogaster. However, Drosophila is highly derived among arthropods with respect to the molecular genetic mechanisms that function during its development. As it is expected that all arthropods have access to the same development "toolkit", some changes are expected based on the observable differences in morphology, making arthropods extremely powerful tools for comparative genomic and molecular genetic studies. In this dissertation I characterize how modifications to the developmental "toolkit" contribute to the evolution of morphological diversity using emerging model arthropod systems. First, as part of a collaboration, I show that several genes expected to be conserved in all arthropods, belonging to the Hox family of transcription factors, have been lost from the genome of a phylogenetically basal arthropod, the two-spotted spider mite Tetranychus urticae. Second, I perform a genomic survey and find an overall reduction in the conservation of Drosophila orthologs from several major signal transduction pathways in the Tetranychus genome in comparison with findings from previous insect surveys. Third, I show that arthropod Hox genes, expected to be found in a tightly linked genomic cluster in most arthropod genomes, are not as tightly clustered as previously thought. Fourth, I show that changes in the genomic arrangement of Tetranychus Hox genes correspond with shifts in their expression and morphological change. Finally, I show the terminal Hox gene Abdominal-B is required for proper axial elongation and segment formation (both segment identity and number) during embryogenesis and metamorphosis in the red-flour beetle Tribolium castaneum. Taken together, these findings advance our knowledge of the evolution of morphological change, with a primary focus on Hox genes and their contribution to axial patterning during development.en
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectdevelopmenten
dc.subjectevolutionen
dc.subjectHox genesen
dc.subjectmorphological diversityen
dc.subjectsignal transductionen
dc.subjectMolecular & Cellular Biologyen
dc.subjectarthropoden
thesis.degree.namePh.D.en
thesis.degree.leveldoctoralen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineMolecular & Cellular Biologyen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorNagy, Lisa M.en
dc.contributor.committeememberNagy, Lisa M.en
dc.contributor.committeememberAntin, Parkeren
dc.contributor.committeememberGutenkunst, Ryanen
dc.contributor.committeememberTax, Fransen
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