A genomic study of the invasive red alga Bangia atropurpurea (Mertens ex Roth) C. Agardh

Abstract

The phylum Rhodophyta comprises the red algae, which are morphologically diverse organisms present in marine and freshwater environments. The red algae order, Bangiales, is an ancient lineage and molecular studies have focused on elucidating the phylogenetic relationships and differentiating species within this group, which is complicated by their known phenotypic plasticity. The genus Bangia (Bangiales) has been observed in both marine coastal environments and in freshwater, and for many years it was thought that the organisms in these habitats were conspecific. Studies showed that the species could acclimate well when transitioning from one habitat to another, with preservation of morphology. Molecular research, however, has shown that the species are not conspecific, and that the freshwater species, Bangia atropurpurea (Mertens ex Roth) C. Agardh, is more closely related to species from the genus Porphyra than to the marine Bangia. This discovery points out other curiosities about B. atropurpurea: it is the only known freshwater Bangiales, it is considered an invasive species of the Great Lakes, is strictly asexual, and has a filamentous thallus while its closest relative has a foliose thallus. To understand the similarities and differences of B. atropurpurea when compared to other Rhodophyta genomes, this thesis investigates the species at a genomic level using high-throughput sequencing and bioinformatics approaches.