Research Group Experimental Taxonomy
Head: Dr. Frank Blattner
In the working group Experimental Taxonomy we use a broad and inclusive definition of taxonomy. It consists of nomenclature (putting the correct name on a taxon), phylogenetics (determining the evolutionary history and relationships of organisms) and systematics (grouping organisms in meaningful units). Thus, we work on fundamental questions of phylogenetic reconstruction of taxon relationships, the evolution of characters, and on the influence of geological and ecological parameters on stability of species and on speciation. We perform these analyses in wild species as well as crops and their closest relatives. The aim of our research is the understanding of mechanisms and processes of speciation (through split of species or via hybridization), cohesion of species (why does speciation not occur?), and the basics of ecological adaptation. As molecular markers contribute today very importantly to plant systematics and genetic processes play a major role in speciation, our work interconnects more and more with genome research. Thus, we are interested in evolutionary processes occurring at the levels from families to genera, species and populations, and the genomic changes accompanying these processes.
Depending on the topics of our studies we use different molecular, microscopic and morphological methods. These include sequence comparisons of chloroplast and nuclear DNAs obtained from Sanger sequencing of single genes and next-generation sequencing (NGS) of many such genes (multilocus analysis). NGS approaches are also used to develop microsatellite markers, arrive at a better understanding of the evolution of microsatellites (SSR-seq), to analyze the genome-wide variation of single-nucleotide polymorphisms (GBS, RAD-seq) and gene expression differences (RNA-seq), or to get insights in genome composition of our study objects (sequence capture, whole-genome shotgun sequencing). These methods are supplemented by optical or electron microscopy, karyotype analysis and genome size estimations (through flow cytometry).
For the analysis of speciation processes we use population genetic and phylogeographic methods (including gene genealogies and network approaches) together with phylogenetic analyses, comparative cultivation of taxa in the field and greenhouse (competition and stress experiments), and field studies during expeditions to the distribution areas of our study taxa (currently mainly in the steppes of the Northern and Southern Hemisphere). These data are supplemented by modeling the potential extant climatic niche of species as well as niche extension during the last glacial maximum about 21,000 years ago. Together with the data of molecular population analyses these data allow estimations of ages of species or species groups, possible ice-age refugia, reconstruction of colonization routes and the evolution of a diverse set of plant characters, as well as changes of stability of ecological niches through time.
Our research objects are currently the wild species of the grass tribe Triticeae (particularly the barley genus Hordeum, the genera of the wheat group Aegilops and Triticum, and polyploid grass species and genera). Moreover, we work on crocuses (about 200 species, among them saffron, Crocus sativus), onions (Allium with about 950 species was for decades a major research topic at IPK; results, publications and databases can be accessed here), St. John’s wort (Hypericum with about 500 species), plants of the Patagonian and Eurasian steppe, and different genera of African cucurbits (Cucurbitaceae). Our studies often result in nomenclatural changes like descriptions of new species (e.g., we recognized and newly described about 70 Allium and 30 Crocus species during the last years), monographs (e.g., for Allium subgenus Melanocrommyum) or new systematic groupings within genera (e.g., for Hordeum) always based on the phylogenetic relationships we inferred.
Within the working group also the herbarium (GAT) of the IPK is currated. This collection currently consists of 600,000 specimens (particularly crop plants and their wild relatives). Parts of this collection are already digitized and can be accessed through the Internet-searchable JACQ Virtual Herbaria site. Digitizing of herbarium vouchers is going on so that large parts of the collection will become available through JACQ.
Research projects of the working group (mostly funded by DFG):
- Vegetation dynamics and climate history of the Euasian steppe belt: Genes documenting history (joint project together with working groups in Osnabruck, Vienna and Barnaul)
- Phylogeny and new classification of Nothoscordum (Alliaceae)
- Determining the influence of polyploidy on the secondary compounds of saffron (Crocus sativus)
- Towards a reference genome of saffron (joint project together with working groups in Dresden and Julich)
- New classification of the genus Crocus based on NGS of multi-locus datasets
- Clarifying relationships among Triticeae grasses using multi-locus analyses and NGS
Finished (selected projects only)
- Species relationships in Hordeum polyploids
- Mechanisms underlying rapid radiations in South American Hordeum species
- Comparative phylogeography of woody plant species of the Patagonian steppe
- The evolutionary history of Hypericum (continued by Nico Nürk, Bayreuth)
- Speciation in SE Asian ant plants of the genus Macaranga associated with Crematogaster ants (continued in Kurt Weising's group at Kassel University)