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Live 2 tell: 400 years of diatom responses to mining pollution

Mid way seminar

Björn Andersson will give his half-time Ph.D. seminar. He is continuing the work of Anna Godhe, studying evolution and ecology of the chain-forming diatom Skeletonema marinoi in the Baltic Sea. Specifically, he is looking at the possibility of heavy metal pollution to drive these processes.

Summary Microalgae have short generation times, flexibility in reproductive strategies, and high standing genetic diversity. This should facilitate rapid evolution, although genetic structure in natural populations is hard to study because blooms are often difficult to predict and monitor through time and space. Several species of microalgae form resting stages that remains viable in the sediments for hundreds of years, which offers an alternative route to study evolution through past events. In my Ph.D. project, I use the two diatom species Skeletonema marinoi and Thalassiosira baltica to follow genetic and phenotypic changes in response to pollution at a copper mine situated by the Baltic sea. In the first Chapter, I develop a high-throughput protocol to determine metal tolerance and find that standardization of the growth conditions is crucial to the reproducibility of the test. Specifically, I show that growth limitation needs to be avoid since it modulates metal sensitivity. In Chapter II, I apply the method to screen 17 individual strains of S. marinoi and T. baltica against 7 metals present in the mining ore. I find noticeable species differences in tolerance, with T. baltica being overall more tolerant to Cu and Ag, and S. marinoi to Cd and Pb. The differences in Cu sensitivity may explain why the copper mining activity coincide with decreased abundance of S. marinoi in the historical sediment record. Chapter III, focuses on evolution of copper tolerance in S. marinoi at the copper mine location. I assemble artificial populations in the lab and test their capacity to evolve tolerance through long-term selection under Cu stress. Only two out of four population have been tested, but preliminary results suggest that there is larger variability in tolerance at the mining exposed site, with fifteen percent of strains being significantly more tolerant then any strain from a reference site. In the last Chapter (IV) I will try to elucidate the physiological and evolutionary mechanism behind Cu tolerance in S. marinoi. I will do so by correlating the phenotypic data of >100 strains screened for Cu tolerance against variation in their genetic code, using a Genome Wide Association Study approach. In the end, my Ph.D. research will enhance our understanding of the evolutionary potential of microalgae in general, and metal tolerance in diatoms specifically.

Supervisors: Kerstin Johannsson, Mats Töpel, Karin Rengefors
Examiner: Helle Ploug
Ph.D. opponent: Ellika Faust

The seminar will also be broadcasted via Zoom.

Lecturer: Björn Andersson

Date: 10/9/2019

Time: 1:00 PM - 2:00 PM

Categories: Science, Research, Sustainable development

Organizer: Institutionen för marina vetenskaper

Location: Botanhuset, Carl Skottsbergs gata 22B, 413 19 Göteborg, sal 11

Contact person: Kerstin Johannesson

Page Manager: Annika Wall|Last update: 6/30/2015

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