Biology and biodiversity of tardigrades in the world and in Sweden : Current status and future visions

Abstract: Tardigrades are small water-dwelling invertebrates that can live almost anywhere in the world. Even though they are well-known our knowledge about them is still scarce. The aim of this study was therefore to explore our current knowledge about tardigrades by: (1) explore their global phylogeny and biogeography based on bioinformatics (2) screen for tardigrades in select locations of northern Sweden and compare with other Swedish locations, and (3) identify at least one tardigrade from northern Sweden and explore the published biomarkers for further identification. The bulk of this thesis was based on evaluation of the Silva database for analyzing SSU (small subunit) and LSU (large subunit) tardigrade sequences and create phylogenetic trees. Some initial lab work was performed using samples of moss and lichen from Piteå, Vindeln and Öland. Results show that only few countries have been explored with regard to tardigrades, and in Sweden more research have been performed in the south compared to the north. The phylogenetic trees give a rough overview of tardigrade relatedness but many of the sequences need to be improved and more sequence work from additional environments is needed. In the lab tardigrades were only found from the Piteå samples, and one of those was identified as Macrobiotus hufelandi, for which a new biomarker was created. Overall, tardigrade research need to continue and expand to other regions in order to understand how these organisms differ between different environments, and more work is needed to ensure higher quality of sequences added to databases.