Taxonomy and phylogenetics of coralline algae

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University of New Brunswick


Understanding species richness and abundance is fundamental to the study of biological systems, however, recent studies suggest that 80-90% of species still await description. This thesis examines the species diversity of an under-explored group of red algae in Canada, the Corallineae (Corallinales, Rhodophyta). Species identification is difficult in this group, largely due to morphological characters that are subject to phenotypic plasticity and morphological convergence. In order to gain a more thorough understanding of species diversity for the Corallineae, I incorporated molecular markers into a modem taxonomic assessment. In particular, the 5' end of the mitochondrial cytochrome c oxidase subunit 1 (COI-5P) DNA barcode was used to assess species boundaries, and additional molecular markers were compared in order to assess congruence to plastid and nuclear DNA regions. Overall I found that instead of the 16 species currently recognized for the Corallineae in Canada there are 36 species in this lineage - more than doubling the number of species for this region. From this unexpected diversity the new species Bossiella robusta K. Hind & G.W. Saunders, sp. nov. and Chiharaea rhododactyla K. Hind & G.W. Saunders, sp. nov. are described here. Additionally, a multigene molecular phylogeny was constructed to determine which morphological characters were useful for classification. I determined that traditional reliance on conceptacle position to discriminate genera in the Corallineae is no longer valid. Two new genera, Ellisolandia K. Hind & G.W. Saunders, gen. nov. and Johansenia K. Hind & G.W. Saunders, gen. nov., were established to accommodate polyphyletic taxa and ensure monophyly at the genus level. In addition, my molecular phylogeny indicated that non-articulated (i.e., crustose) taxa resolved within the subfamily Corallinoideae. This is the first evidence of crustose taxa within this lineage and indicates that a re-examination of distinguishing morphological characters at the subfamily level is warranted. This thesis illustrates the taxonomic complexities inherent in examining cryptic and pseudo-cryptic taxa and suggests that the incorporation of multiple molecular markers in combination with thorough morphological assessments are required for the adequate discovery and description of coralline taxa.