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UBC Theses and Dissertations
Transcriptome sequencing of Trichonympha from Reticulitermes hesperus and multi-protein phylogenetic analysis of selected Spirotrichonymphids, Cristamonads, and Trichonymphids Cooper, Caryn
Parabasalid protists include may obligate termite gut symbionts that play important ecological roles, permitting their hosts to digest cellulose. One of the earliest-identified groups of parabasalids is the hypermastigote Trichonymphids, of which Trichonympha is the type species. The purpose of my thesis was to illustrate deep phylogenetic relationships between selected species of Trichonymphids and the other parabasalid groups Spirotrichonymphids and Cristamonads, and to compare the results of using multiple sequences against a single sequence for phylogenetic analyses in these groups. To this end, I sequenced the transcriptomes of Trichonympha cells isolated from a Pacific Coast population of Reticulitermes hesperus, and I used multi-sequence phylogenetic techniques to resolve the phylogeny of Trichonymphida and other Parabasalian groups beyond what has previously been done with the use of SSU-based phylogenetic analyses. I successfully isolated two Trichonympha cells via single-cell picking techniques and sequenced their transcriptomes. I annotated these transcriptomes for protein-coding genes and used the subsequent translated protein sequences, along with translated transcriptomes of other Trichonymphids, to construct a 14-sequence dataset for a multi-gene phylogenetic analysis. I also constructed a SSU sequence dataset for comparison. I used maximum-likelihood algorithms to construct phylogenetic trees from each dataset to illustrate the deep phylogeny of trichonymphids. The phylogeny thus generated agreed with previous phylogenies of Parabasalia, recovering Trichonymphids, Spirotrichonymphida, and Cristamonads as monophyletic. Additionally, I used SSU sequence data to confirm that the single Trichonympha species present in R. hesperus is phylogenetically distinct from Trichonympha agilis, despite previous literature claiming that T. agilis was present both in R. flavipes and R. hesperus and was the only Trichonympha in the latter. Therefore, the R. hesperus Trichonympha requires a full taxonomic description as a novel species, and the epithet T. agilis should be restricted to the species of Trichonympha in R. flavipes. I also confirmed, using COX-2 sequence data, a 2005 report from Austin et. al. synonymizing R. flavipes and R. santonensis.
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