Genomic and Transcriptomic Insights on the -Orbicella- Species Complex
Open Access
- Author:
- Gonzalez Angel, Ana Maria
- Graduate Program:
- Biology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- July 11, 2019
- Committee Members:
- Monica Medina, Dissertation Advisor/Co-Advisor
James Harold Marden, Committee Chair/Co-Chair
Stephen Wade Schaeffer, Committee Member
Istvan Albert, Outside Member
Stephen Wade Schaeffer, Program Head/Chair - Keywords:
- Coral Reefs
Orbicella
genomics
transcriptomics
speciation
reproductive isolation - Abstract:
- In this dissertation I explore different aspects of the ecological speciation and genomics of marine organisms. First, I review the literature and explore different factors, particularly, depth, that isolate marine populations. These factors can be sufficiently strong to enhance divergence among populations, and so, lead to reproductive isolation. I discuss numerous examples but focus on the well documented case of Orbicella, a Caribbean coral genus that is environmentally segregated and has evolved at least two mechanisms of reproductive isolation, temporal isolation and gamete recognition. In Chapter 2, I explore the genomes of these corals to infer how different their protein coding ortholog groups are and if gene content is reflected in the differentiation in these taxa. Overall, I found the genomes of Orbicella sister species are extremely similar and other factors may be responsible for their differentiation such as gene expression, gene silencing, differential transcription factor activity or SNP presence. In Chapter 3, I study the temporal isolation by assessing the gene expression profiles of two sister Orbicella species during and after the moment of spawning, which occurs only one time per year. Although their genomes are very similar, gene expression profiling suggests these species use their genetic toolkit very differently. Minimal overlap was found in the differentially expressed genes (DEG) involved in the spawning behavior, and the ones that do not overlap have different identities and putative functions while many others are remain uncharacterized and unknown. Further studies including more timepoints are need to address the rhythmicity of the DEG putatively responsible for the allochronic assortative mating (or timing of gamete release) that occurs in Orbicella. Other aspects of the reproductive barriers such as gamete recognition and hybrid inviability also require attention. Overall, the studies of the genomic and cellular elements responsible for the prezygotic isolation in Orbicella are still nascent and warrant more work to unravel their complexity and consequences in ecology and evolutionary history of this group.