Evolution, ecology and genomics of the Great Lakes invader, the red algal species Bangia atropurpurea.

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The red algae (Rhodophyta) are an ancient lineage in the fossil record dating 1.2 and 1.7 Ga; both of these fossils have pushed back the evolution of multicellularity in eukaryotes and the evolution of sexual reproduction. Furthermore, the red algae are a critical group in the evolution of photosynthetic life on earth containing primary chloroplasts and have also contributed chloroplasts through secondary and tertiary endosymbiosis to other eukaryotic lineages. Despite the obvious importance of this group, little is still known about many red algal lineages, in particular, the more basal classes within the phylum. Only recently, has genomic sequencing been used to examine members of this phylum and have noted differences among the red algae and other eukaryotes, as well as unique stress tolerances. In this proposal, we aim to sequence the genome and selected transcriptomes of the species Bangia atropurpurea. This research proposal would be the first to sequence the genome of a strictly freshwater red algal species, and this species is also an invader in the Laurentian Great Lakes. It is important to note that Bangia is the only genus in the red algae to have a species solely in freshwater (not brackish) and others in the marine environment and it is the only red alga to have been shown to experimentally transition from marine to freshwater or vice versa. Hence, this genus is an excellent model organism to examine transcriptomic changes due to osmotic stress and we will be able to identify genes that are involved in the process of acclimation and osmotic stress and predict the limits that control invasion into new habitats. In addition, the 1.2 Ga red algal fossil is morphologically indistinguishable from Bangia and hence is the oldest taxonomically resolved eukaryote fossil. This fossil provided the first evidence for sexual reproduction in the fossil record for eukaryotes and as a result, this genus is ideal to study the evolution of sexual reproduction as well as the expression of genes in different stages of the life history. Bangia atropurpurea is known to only reproduce asexually, and this particulary mode of reproduction enables it to be an effective invader into new habitats.