Global species structure, colonization-extinction dynamics and adaptive radiation of the cosmopolitan diatom clade Pinnularia borealis.

Diatoms, unicellular algae with a siliceous cell wall, are ecologically widespread and highly diverse organisms. Until recently, it was believed that most diatom species are worldwide distributed. However, increasing evidence suggests the opposite to be true for many species. Phylogenetic data revealed that our model species Pinnularia borealis consists of morphologically similar forms, which in fact correspond to different species. With this project we aim to test a series of hypotheses based on an in depth study of this species complex. First, we will develop and characterize a culture collection of Pinnularia borealis strains from various regions using a combination of morphology, genetics and ecophysiology. This will allow us to assess to which extend ecophysiological specialization is correlated with species formation and their global distribution during the evolution of the complex since its inferred origin 30-47 mil. years ago. In addition, the project will use targeted sequencing of environmental samples and phylogeographic analysis to document patterns of local and regional diversity of this complex in ice-free regions in Antarctica and the Arctic representing a range of lake provinces differing in age and degree of geographical isolation. This will allow us to test the relative roles of dispersal constraints and local adaptation for understanding species distributions.

Keywords:BIODIVERSITY, MOLECULAR GENETICS

Disciplines:Geology, Aquatic sciences, challenges and pollution

Project type:Collaboration project