Molecular-assisted investigations of evolutionary relationships, species diversity and biogeography for selected species of the red algal genera: Antithamnionella, Ceramium, Hollenbergia, Neoptilota, Ptilota and Scagelia (Ceramiales, Rhodophyta)

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University of New Brunswick


In this thesis I have applied a contemporary molecular-assisted approach to resolve outstanding uncertainty surrounding diversity, distributions and evolutionary relationships for species within six red alga genera reported for Canadian waters: Antithamnionella, Ceramium, Hollenbergia, Neoptilota, Ptilota and Scagelia. This investigation has uncovered numerous inconsistencies with published accounts for these taxa. In my second chapter I presented the first genetically confirmed records of Antithamnionella floccosa for the Canadian Pacific. As well, I presented evidence that the three species of Scagelia reported for Canada, S. americana, S. occidentale and S. pylaisaei, are synonymous. In my third chapter the results of my multi-gene phylogenetic analyses demonstrated that the currently held hypothesis of evolutionary relationships among species of Neoptilota and Ptilota are inaccurate. Furthermore, species diversity for this group was previously under estimated, thus I have described five new taxa: Ptilota gwaiihaanasica nom. prov.; Ptilota haidarum nom. prov.; Ptilota pseudohypnoides nom. prov.; Ptilota sloanii nom. prov.; and Ptilota subita nom. prov.; as well as reinstated Ptilota tenuis. In my fourth chapter I identified a cryptic species complex for Ceramium virgatum in the northwest Atlantic and employed population genetic analyses that established one of the species within this complex, C. secundatum, is not native to this region. Collectively, these results have further emphasized that the incorporation of molecular tools into systematic investigations of red algae is imperative in order to achieve a greater understanding of species diversity and distributions.