Date of Degree
PhD (Doctor of Philosophy)
Budd, Ann F.
First Committee Member
Second Committee Member
Third Committee Member
Fourth Committee Member
Reef-building corals (Order: Scleractinia) are undergoing rapid taxonomic revision after molecular systematics disputed the relationships at all taxonomic levels within traditional classification. New morphological characters are being used to produce evolutionary relationships supported by molecular phylogenetics. While these characters are providing more congruent taxonomic relationships, their variation has not been fully explored. Additionally, phenotypic plasticity (changes in morphology resulting from environmental factors influencing the expressed phenotype despite a shared genotype) is prevalent amongst Scleractinia. In order to better understand the nature of these characters and explore their variation, I created a series of aquaria-based experiments designed to test the stability of these new morphological characters in response to differing environmental conditions. Light intensity and temperature were chosen as the environmental factors varied in these experiments on the basis of being a known trigger for environmentally-driven plasticity and their importance in calcification rate. In addition to aquaria-based phenotypic plasticity experiments I also examined a group (Family: Euphylliidae) within Scleractinia that had been divided by molecular phylogeny into two disparate groups. My research focused on morphological features viewed at magnifications observable by scanning electron microscopy (SEM) called micromorphology. Although variation in the skeletal micromorphology is observable, the new morphological characters that are used in taxonomy display only small amounts of variation caused by changing environmental conditions and were found to be stable for use in taxonomic studies. Additionally, I found a few micromorphological features distinguishing the two groups previously assigned to Euphylliidae including the shape of the septal margins and the fine-scale skeletal texture.
Climate change, Micromorphology, Microstructure, Phenotypic plasticity, Reef ecology, Scleractinia
xiii, 207 pages
Includes bibliographical references (pages 165-171).
Copyright 2016 Matthew A. Tibbits
Tibbits, Matthew Alan. "Scleractinian micromorphology : taxonomic value vs. phenotypic plasticity." PhD (Doctor of Philosophy) thesis, University of Iowa, 2016.
Additional FilesCaulastraea Temp 3D.zip (266 kB)
Caulastraea Temp 3D.zip
Dipsastraea light 3D.zip (267 kB)
Dipsastraea Light 3D.zip
Dipsastraea Temp 3D.zip (535 kB)
Dipsastraea Temp 3D.zip
Euphylliidae specimen macro photos.pdf (654 kB)
Euphylliidae Specimen Macro Photos.pdf
Galaxea Temp 3D.zip (27 kB)
Galaxea Temp 3D.zip
Micromussa light 2D.zip (200 kB)
Micromussa Light 2D.zip
Micromussa light 3D.zip (349 kB)
Micromussa Light 3D.zip
Caulastraea 2D light.zip (136 kB)