Format: ORAL

Marco Dorfner1, Sarah Eder1, Johannes Gssele1, Tankred Ott1, Robert Vogt2 Christoph Oberprieler1

1 University of Regensburg, Regensburg, Germany. 2 Freie Universität Berlin, Berlin, Germany.

Gene flow at the diploid and polyploid level, multiple formation of polyploid species, often under reciprocal parentage, and the young age of polyploid species radiations account for the taxonomy of polyploid complexes being the ultimate challenge for a DNA-based, phylogenetic species-delimitation approach. Additionally, reconstructions of the evolutionary history of polyploid complexes are still hampered by the lack of explicit methods for the reconstruction of reticulate (species) phylogenies. The present contribution summarizes the state-of-the-art of our project aiming at the establishment of a methodological pipeline for species delimitation and phylogenetic reconstructions in the polyploid complex of the genus Leucanthemum Mill. (ox-eye daisies; Compositae-Anthemideae), which comprises around 43 species with ploidy levels between 2x and 22x. At the diploid level, species discovery and validation methods based on genetic, ecological, geographical, and morphometric datasets were applied to test the currently accepted diploid morphospecies, i.e., hitherto morphologically delimited taxa. Novel approaches were taken in the analyses of RADseq data (consensus clustering), morphometrics of reconstructed leaf silhouettes from digitized herbarium specimens, and quantification of species-distribution overlaps. We show that 17 of the 20 Leucanthemum morphospecies are supported by genetic evidence. At the tetraploid level, the same methodological approach revealed the evolutionary relationships among additional eight morphospecies and resulted in an adequate taxonomic treatment of these taxa. Further results are presented for species-delimitation and phylogenetic studies in the L. atratum-group, which comprises diploid and hexaploid taxa, and in the decaploid L. pachyphyllum-group. While in the former double-digest Genotyping-by-Sequencing (ddGBS) was used for genetic fingerprinting, the latter study was based on a newly established Nanopore-based AFLPseq procedure and bioinformatic analysis pipeline.