Taxon recruitment and evolution of the arctic flora - the synthesis

• Applicant: Dr. Matthias H. Hoffmann
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: from 2010 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 167692306

• Final Report Year: 2018

Final Report Abstract

The Arctic is a very young ecosystem dating about 3.2 myr ago, although first regional patches of arctic tundra vegetation appeared earlier in the history of the Earth. In spite of its recent origin of arctic vegetation and virtually no predecessor in terms of ecosystems, the Arctic harbours about 2,800 species of higher plants. The origins of these species were almost unknown. We wanted to reveal the origins of the arctic species in terms of ecology, biogeography, molecular phylogenetic background, and time. Explicitly, we focussed on species level inferences and methods instead of phylogeographic analyses that cover usually more recent time frames. Species-rich genera of the Arctic were selected as representatives for the northernmost ecosystem. For almost all arctic species and many non-arctic relatives molecular phylogenetic trees were calculated and subsequently analysed with respect to systematics and taxonomy, distribution, ecology, as well as morphology and karyology. The species assembly of the Arctic is a highly dynamic and very complex process that shows, however, some recurrent patterns. Arctic plants may had their origins in almost all more or less adjacent areas and ecosystems, from lowlands to high mountains. Arctic plants have seemingly evolved from almost all ecosystems, i.e. vegetation units of the adjacent areas. These were predominantly different kinds of temperate to boreal forests, bogs and swamps, high mountain tundra but also subalpine vegetation, steppes and coastal vegetation. An origin in very dry areas was, however, rarely observed. Arctic species evolved usually many times in parallel, although radiations in the North were comparatively rare. Some plant lineages of the Arctic may have evolved earlier than the circumarctic ecosystem appeared, others very recently, probably in postglacial times. No clear morphological adaptations for the life in the Arctic were observed.

Publications

• (2012): Not across the North Pole: Plant migration in the Arctic. New Phytologist 193: 474-480
  Hoffmann, M. H.
  
• (2013): Rapid and recent worldwide diversification of bluegrasses (Poa, Poaceae) and related genera. PLoS One 8: e60061
  Hoffmann, M. H., Schneider, J., Hase, P., Röser, M.
  
• (2014): High mountain origin, phylogenetics, evolution, and niche conservatism of arctic lineages in the hemiparasitic genus Pedicularis (Orobanchaceae). Molecular Phylogenetics and Evolution 76: 75-92
  Tkach, N., Ree, R. H., Kuss, P., Röser, M., Hoffmann, M. H.
  
• (2014): Parallel and convergent diversification in two northern hemispheric species-rich Carex lineages (Cyperaceae). Organisms Diversity and Evolution 14: 247-258
  Gebauer, S., Starr, J. R., Hoffmann, M. H.
  
• (2015): Making Carex monophyletic (Cyperaceae, tribe Cariceae): a new broader circumscription. Botanical Journal of the Linnean Society 179: 1-42
  Global Carex Group
  
• (2015): Molecular phylogenetics, character evolution and systematics of the genus Micranthes (Saxifragaceae). Botanical Journal of the Linnean Society 178: 47-66
  Tkach, N., Röser, M., Hoffmann, M. H.
  
• (2015): Molecular phylogenetics, morphology and a revised classification of the complex genus Saxifraga (Saxifragaceae). Taxon 64: 1159-1187
  Tkach, N., Röser, M., Miehe, G., Muellner-Riehl, A. N., Ebersbach, J., Favre, A., Hoffmann, M. H.
  
• (2015): Molecular phylogeny of the species-rich Carex sect. Racemosae (Cyperaceae) based on four nuclear and chloroplast markers. Systematic Botany 40: 433-447
  Gebauer, S., Röser, M., Hoffmann, M. H.
  
• (2016): Footprints of the Last Glacial: Past competition may have shaped strongly disjunct distribution ranges in Artemisia rupestris and A. laciniata. Flora 224: 203-210
  Hochheimer, J., Hoffmann, M. H.
  
• (2016): Megaphylogenetic specimen-level approaches to the Carex (Cyperaceae) phylogeny using ITS, ETS, and matK sequences: Implications for classification. Systematic Botany 41: 500-518
  Global Carex Group
  
• (2016): Quantitative morphological and molecular divergence in replicated and parallel radiations in Carex (Cyperaceae) using Symbolic Data Analysis. Systematic Botany 41: 552-537
  Hoffmann, M. H., Gebauer, S.
  
• (2017): Assembly of the arctic flora - highly parallel and recurrent pattern in sedges (Carex). American Journal of Botany 104: 1334-1343
  Hoffmann, M. H., Gebauer, S., von Rozycki, T.