An exploration into the phylogenetics of thin, filamentous cyanobacteria: The use and utility of morphological, ecological and molecular data in cyanobacterial systematics.





Paper Type

Master's Thesis


College of Arts and Sciences

Degree Name

Master of Arts in Biology (MA)



College Dean

Dr. Barbara A. Hetrick


My research explored the phylogenetic relationships of thin, filamentous cyanobacteria utilizing morphological, ecological and molecular data. Cyanobacteria are among the oldest, most abundant and ecologically important group of organisms on the planet. They are a group of oxygenic, photosynthetic prokaryotes that have chlorophyll a and phycobilisomes. Currently, the state of cyanobacterial systematics is changing due to the rapid developments in molecular phylogenetic techniques allowing for more accurate relationships to be hypothesized and tested. My research focused on determining how molecular data, combined with tradition morphological and ecological data, could be utilized to help recreate accurate phylogenetic relationships within the Oscillatoriales (a filamentous, non-heterocyst order of cyanobacteria). In particular, my research examined the phylogenetic relationships of the genera Geitlerinema, Limnothrix, and Leptolyngbya. I found that the genera Geitlerinema and Limnothrix are both polyphyletic lineages when utilizing the 16S rRNA gene for phylogeny reconstruction. Additionally, within these circumscriptions are two well supported Operational Taxonomic Units (OTU) that do not correspond to Geitlerinema or Limnothrix sensu stricto, and may be new genera. However, without a clear morphological character, the circumscription of these OTU’s was not possible. In the examination of the genus Leptolyngbya, I found that this genus was polyphyletic based on the 16S rRNA gene sequence data. Additionally, I was able to describe a new genus of cyanobacteria from within the Leptolyngbya based on molecular and morphological data. This new genus was named Nodosolinea for the unique autapomorphy of nodule formation on filaments under conditions of low light.

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