Towards a resolved phylogeny for a new classification of Crocus L. (Irididaceae)

• Applicant: Dr. Dörte Harpke
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 327155231

The genus Crocus, comprising about 200 species, requires a taxonomic revision as several infrageneric and even intraspecific units were shown to be para- or polyphyletic and over 50 new species were described recently but, in most cases, not assigned to existing taxonomical groups. Moreover, as up to now phylogenetic investigations failed to produce a resolved phylogeny also the affiliation of several species and infrageneric groups is still unclear and it is not possible to establish a new classification. To obtain a resolved phylogeny, 25 chloroplast and nuclear markers will be sequenced using high-throughput technologies and analyzed with coalescent-based methods. Combined with our ongoing thorough morphological investigations we will be able to evaluate the most useful combination of morphological characters for (i) a new classification of the genus and to set the framework for the new monograph of the genus we are already working on. The obtained phylogeny will also be used to (ii) to clarify the geographical origin of the genus and its main lineages as well as getting insight into speciation/radiation processes by reconstructing the historical biogeography of the genus and divergence time estimations. In Crocus, it is evident by widely varying chromosome numbers (2n = 6 to 70) that dysploidy played an important role in differentiation processes. To (iii) get more insights on the impact of dysploidy on speciation process in Crocus genome sizes and chromosome numbers will be obtained and considered in a phylogenetic context. Generally, although common in angiosperms, dysploidy was studied in an evolutionary context only in few genera. Therefore, with Crocus an additional system could be studied to more generally infer the possible role of dysploidy in plant evolution. In addition to geographical isolation and reproductive isolation by dysploid chromosome numbers, speciation processes seem to be partly driven by hybridization in Crocus. Therefore, (iv) polyploid as well as homoploid hybridization events will also be inferred through the multi-locus analysis.

• DFG Programme: Research Grants