Abstract Detail

Biogeography

Bradican, John Paul [1], Karbstein, Kevin [2], Tomasello, Salvatore [1], Dunkel, Franz [3], Pätzold, Claudia [4], Hodač, Ladislav [5], Hörandl, Elvira [1].

Species delimitation at marginal areas: Range expansion of the apomictic polyploid Ranunculus auricomus complex following the Last Glacial Maximum.

The delimitation of species within evolutionarily young plant complexes poses a substantial challenge to taxonomists. Knowledge gleaned from the development of such complexes can provide keen insights into rapid speciation processes. Here the palearctic Ranunculus auricomus species-complex is investigated in order to gain such insights. Characteristic of this group are the frequent occurrence of polyploidy, facultatively asexual reproduction via seed (apomixis), morphological complexity, hybridization and shallow divergence of lineages leading to highly reticulate relationships. Recent work has elucidated that this species-complex has originated from five sexual progenitor species via extensive hybridization between these progenitors as well as between their apomictic descendants. However, previous research has largely focused on the central-European populations of this group. Reproductive and phylogenetic characteristics of R. auricomus inhabiting its range margins (comprising southern-Europe and the Arctic into western-Alaska) have remained largely undescribed, resulting in a dearth of understanding of species-relationships in these areas. Interestingly, some morphologically distinct members of this complex occur primarily in alpine habitats, the Arctic and central-Asia (e.g. Ranunculus monophyllus s.l,) whose relationship to other members of the complex remains largely unclear. The evolutionary origin of these tetra- to hexaploid lineages, as well as their diversification in time and space remain to be studied. Research into such marginal populations may also inform our understanding of the considerable expansion of this complex from the southern Alps following the Last Glacial Maximum (LGM). Utilizing target enrichment of 736 nuclear genes combined with somatic-tissue ploidy determination, phylogenetic analyses of over 100 populations throughout Europe, primarily consisting of representatives from both the northern and southern-European climatic margins are underway. Sequence data informed by ploidy level of individual specimens has allowed for allele-phasing techniques to be applied, enhancing the phylogenetic resolution. Using these methods, sub-genomic elements may be identified, and the contribution of different sub-genomes may be tracked in space. Additionally, data on the mode of reproduction using flow cytometric seed screening suggest predominantly obligate apomixis in populations at the northern climatic margins of the species-complex. In this talk, I will present results from these analyses pertaining to the biogeography, molecular dating, and reproductive characteristics of this group at its range margins, whereby geographic clustering of lineages is observed, as well as describing the workflow and future applications. I will also compare non-ploidy informed phylogenies and results obtained utilizing allele-phasing methods. Such techniques are applicable towards other shallowly-divergent species complexes with broad climatic ranges.

Related Links:
Home Page John Paul Bradican

1 - Georg-August Universität Göttingen, Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Untere Karspüle 2, Göttingen, NI, 37073, Germany
2 - University of Göttingen, Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Untere Karspüle 2, Göttingen, Lower Saxony, 37073, Germany
3 - Am Saupurzel 1, Karlstadt, BY, 97753, Germany
4 - Senckenberg Research Institute and Natural History Museum, Botany and Molecular Evolution, Senckenberganlage 25, Frankfurt am Main, HE, 60325, Germany
5 - Max Planck Institute for Biogeochemistry, Department of Biogeochemical Integration, Ehrenbergstraße 29, Ilmenau, Th, 98693, Germany

Keywords:
biogeography
polyploidy
Ranunculus auricomus
Target Enrichment
apomixis
arctic
Subarctic.

Presentation Type: Oral Paper
Number: BIOG I005
Abstract ID:246
Candidate for Awards:None