Population genomic comparison of Fragilariopsis kerguelensis, a Southern Ocean diatom

In the Southern Ocean, diatoms together with other phytoplankton, are the base of the food webs. Fragilariopsis kerguelensis as the most abundant and truly Antarctic diatom species, might have important effects on organisms that depend on it. Additionally, this species can influence nutrient cycles and global climate. Therefore, Fragilariopsis kerguelensis, can be an important species to predict possible effects of climate change. Recent distribution studies performed in the Laboratory of Hustedt Diatom Study Centre, Polar Biological Oceanography Section at the Alfred-Wegener-Institut, using public taxon observations alongside observations from material housed there, prospected that ocean warming will affect Fragilariopsis kerguelensis around the northern edge of its distribution area. As a result, this species might be developing genotypic adaptations to these changing environmental conditions. According to the data available and ecological relevance, this thesis reviewed sea surface temperature (SST), as well as other environmental parameters such as nitrate, phosphate, and silicate. Northern and southern populations of this species were characterized using dou-ble digest restriction-site associated DNA sequencing (ddRAD). The molecular results ob-tained suggest that these environmental parameters are correlated with the genetic differen-tiation of Fragilariopsis kerguelensis. A particular locus of Fragilariopsis kerguelensis was identified to be seemingly sensitive to the changing conditions in the Southern Ocean. This was “Phaeodactylum tricornutum CCAP 1055/1 predicted protein partial mRNA”, also found in another pennate diatom. Nonetheless, the major challenge was to understand the simultaneous effects of these param-eters