Evolution, morphology, and gene expression of functionally specialized zooids in Siphonophora

Munro, Catriona

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Year:: 2019
Contributor:: Munro, Catriona (creator); Kellner, James (Reader); Rand, David (Reader); Edwards, Erika (Reader); Dunn, Casey (Advisor); Brown University. Biology and Medicine: Ecological and Evolutionary Biology (sponsor)
Genre:: theses
Subject:: Gene expression; Cnidaria; Siphonophores; Anatomy, Comparative; Animal colonies; Functional specialization
Extent:: xxviii, 203 p.
DOI: https://doi.org/10.26300/5aaw-fp72

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Abstract:: Siphonophores are colonial marine hydrozoans (Cnidaria) that are composed of many bodies (zooids) that are each functionally specialized for a particular task, including feeding, swimming and reproducing. Functionally specialized zooids differ from one another not only in function, but also in their cellular composition. In this dissertation, I investigate functional specialization in siphonophore zooids, with a particular emphasis on differences in gene expression. In my first chapter, I provide a description of the morphology and development of the Portuguese man of war, Physalia physalis. Using new photographs and 3D microscopical images, I provide insight into development, colony growth, and the evolutionary origins of a unique functionally specialized zooid — the tentacular palpon. In my second chapter, I investigate the evolutionary relationships of siphonophores, building a phylogeny using transcriptome data from 33 siphonophore species and 10 outgroups. This new phylogeny finds strong support for many previously identified groups, but also resolves many deep relationships. The products of this chapter, including the species phylogeny, de novo transcriptomes, and gene phylogenies, provide an important foundation for subsequent chapters. In my third chapter, I investigate gene expression patterns across different zooids in seven siphonophore species. Gene expression patterns are used to understand which genes show zooid-specific expression in particular species and also which genes are conserved across all species. Expression patterns are also used to investigate the function of novel zooid types. In my fourth and final chapter, I apply phylogenetic methods to compare expression patterns across species. Expression patterns are mapped directly onto gene phylogenies, and speciation and duplication nodes are labelled. I was able to investigate evolutionary changes in expression by isolating branches in gene trees that correspond to branches in the species tree. Through each of these chapters I was able to apply modern methods and techniques to address old questions about the evolution of functional specialization. Optical projection tomography enabled new insights into the 3D branching of Physalia physalis, while gene expression data enabled totally new perspectives on the function and evolution of specialized zooids, most notably palpons.
Notes:: Thesis (Ph. D.)--Brown University, 2019

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Rights: In Copyright
Restrictions on Use: Collection is open for research.

Citation

Munro, Catriona, "Evolution, morphology, and gene expression of functionally specialized zooids in Siphonophora" (2019). Ecological and Evolutionary Biology Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.26300/5aaw-fp72

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Ecological and Evolutionary Biology Theses and Dissertations

Theses and Dissertations for the Ecological and Evolutionary Biology department.
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