Background and Academic Interests
I joined the Plant Evolution and DNA Metabarcoding group in 2015 and I work on speciation genetics in Arctic plants as a part of the SpArc team. My background is in Arctic plant ecology and conservation genetics and I have my master’s degree from the University Center in Svalbard (UNIS) and the University of Oslo. In my master project I worked with some of Svalbard’s rarest plant species and became fascinated by their biology. Arctic plants have to survive in an extreme environment with short growing seasons and a risk of subzero temperatures even in summer. Furthermore, many Arctic plant species are highly self-fertilizing resulting in diploid populations with little genetic variation. Recently, researchers at NHM made the surprising discovery that crosses between populations of the same Arctic plant species frequently result in partial hybrid sterility. In my PhD project I examine why Arctic plant populations evolved reproductive isolation so rapidly to form new "biological species." In addition, I will investigate the molecular evolution of cold tolerance in several species of Arctic Brassicaceae.
Project description: Speciation genetics and molecular evolution of cold tolerance in Arctic plants and searching for cryptic species in the Mediterranean flora
The SpArc project (Speciation genetics in Arctic plants and searching for cryptic species in the Mediterranean flora) follows from recent findings in arctic diploid plants, revealing high biological speciation rates in the Arctic flora. Based on the surprising discovery that interpopulational crosses of Draba fladnizensis were entirely sterile (Brochmann et al. 1993), it has subsequently been demonstrated that postzygotic reproductive barriers are remarkably common within several well-defined Arctic species. We posit that this pattern may be related to the existence of small effective population sizes due to a predominantly selfing mating system in these plants (Grundt et al. 2006; Gustafsson et al. submitted). Understanding the underlying genetic architecture of this kind of “cryptic speciation” will yield valuable insights into the earliest stages of species formation. In addition, the findings contradict the traditional view of the Arctic as an “evolutionary freezer”, i.e. having relatively low rates of species formation due to extreme environmental constraints and repeated glaciations (Brochmann & Brysting 2008; Mittelbach et al. 2007). If comparatively reduced rates of cryptic speciation formation are found in more southern floras, these results could even challenge the latitudinal diversity gradient - one of the oldest recognized patterns in ecology. The main aims of the SpArc project are therefore to i) characterize the genetic architecture and mechanisms of postzygotic reproductive isolation in the Arctic species Draba nivalis and Coechlaria groenlandica; and ii) to test whether the Mediterranean flora contains similarly high, but hitherto undetected biological species diversity and whether this pattern is correlated with mating system. Expanding on these aims, my PhD research projects will also iii) examine the various modes of gene action contributing to differences in hybrid fitness in a set of predominantly selfing species; and iv) investigate the molecular evolution of cold tolerance in the Brassicaceae family, as adaptation to low temperatures likely has been important in Arctic plant speciation.
- Birkeland, Siri; Skjetne, Idunn Elisabeth Borgen; Brysting, Anne Krag & Alsos, Inger Greve (2017). Living on the edge: conservation genetics of seven thermophilous plant species in a high Arctic archipelago. AoB Plants. ISSN 2041-2851. 9(plx001) . doi: 10.1093/aobpla/plx001
- Alsos, Inger Greve; Ehrich, Dorothee; Eidesen, Pernille Bronken; Solstad, Heidi Merethe; Westergaard, Kristine Bakke; Schonswetter, Peter; Tribsch, Andreas; Birkeland, Siri; Elven, Reidar & Brochmann, Christian (2015). Long-distance plant dispersal to North Atlantic islands: colonization routes and founder effect. AoB Plants. ISSN 2041-2851. 7(1), s 1- 19 . doi: 10.1093/aobpla/plv036 Full text in Research Archive
- Westengen, Ola Tveitereid; Okongo, Mark Atam; Onek, Leo; Berg, Trygve; Upadhyaya, Hari; Birkeland, Siri; Khalsa, Siri-Dharma Kaur; Ring, Kristoffer Hofaker; Stenseth, Nils Christian & Brysting, Anne Krag (2014). Ethnolinguistic structuring of sorghum genetic diversity in Africa and the role of local seed systems. Proceedings of the National Academy of Sciences of the United States of America. ISSN 0027-8424. 111(39), s 14100- 14105 . doi: 10.1073/pnas.1401646111
- Cerca de Oliveira, José; Birkeland, Siri; Magnussen, Trude & Kistenich, Sonja Daniela (2017). Forskere krangler om kryptiske arter. Forskning.no : nettavis med nyheter fra norsk og internasjonal forskning.
- Gustafsson, A Lovisa S; Birkeland, Siri; Gizaw, Abel; Rieseberg, LH; Slotte, Tanja; Nowak, Michael & Brochmann, Christian (2017). Searching for genetic mechanisms of plant speciation in the Arctic.
- Brysting, Anne Krag; Birkeland, Siri & Kaur Khalsa, Siri-Dharma (2012). Eksotiske frukter.