Date of Award
Master of Science (M.S.)
First Committee Member
Second Committee Member
Model organism studies have been fundamental in understanding evolutionary and developmental biology. However, non-model organisms present opportunities to study unique characteristics and as comparisons to model organisms, leading us toward broader and more relevant perspectives on diversity. The Euphilomedes genus of ostracods is an example of a non-model group with potential for evolutionary and developmental studies.
Ostracoda is an ancient, basally branching lineage of Crustaceans with a complete and prodigious fossil record. Despite the group’s promise for evolutionary studies, much remains unknown about the basic biology of this clade. There are a limited number of embryogenesis studies in Ostracoda; here, I study development in Euphilomedes.
In Chapter 1, I study the main events in Euphilomedes’ embryology, focusing on cleavage and cell migration. I describe the general embryology of Euphilomedes, and devise a visual staging scheme for their development. Using fluorescent nuclear staining and microscopy, I visualize nuclei in cleavage throughout development of nuclear divisions and migrations during development. The meroblastic cleavage observed in Euphilomedes resembles that of another Myodocopid ostracod, Vargula hilgendorfii.
Finally, immunostaining for acetylated-alpha tubulin and phalloidin staining are used to visualize the general anatomy of the embryonic brain. This provides new protocols for visualizing the nervous system, enabling more detailed nervous system studies in the future.
In Chapter 2, I explore differential gene expression patterns in the developing eyes of juvenile Euphilomedes. Euphilomedes have sexually dimorphic eye types – males have lateral compound eyes, while females instead have eye rudiments. Previous studies in E. carcharodonta show that genes in the retinal determination and phototransduction gene networks have differential expression in males and females during eye development. In this thesis, we attempt to compare these patterns to expression in a sister species, E. morini.
Koyama, Kristina. (2017). Studies on development in Euphilomedes ostracods: Embryology, nervous system development, and the genetics of sexually dimorphic eye development. University of the Pacific, Thesis. https://scholarlycommons.pacific.edu/uop_etds/2978