A new story told by herbarium collections – unraveling the patterns of clonal diversity

• Applicant: Dr. Juraj Paule
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 508233416

Although natural history collections were typically not established with the aim of capturing population level variability, invaluable information can now be retrieved. Next Generation Sequencing (NGS) facilitates comprehensive analyses and makes for the first time detailed assessments of genetic change at the population-level feasible. NGS allows for thorough investigation of genetic makeup of numerous specimens, even for fragmented and poorly preserved DNA typically found in collection specimens. Understanding the mechanisms of evolution requires information on the rate of appearance of new mutations and their effects at the molecular and phenotypic levels. The major challenge is that genetic changes have rarely been observed directly. Direct observations of genetic change are restricted to very few short-term lab studies, or to analyses of historical samples that typically suffer from low sample sizes and restrictions with respect to genetic markers and studies covering entire population and assessing a large part of their genomes are lacking. Hence, the museum specimens significantly help to bridge the gap between traditional ancient DNA studies (long-time, low genome coverage, low sample size) and lab observations (short-time, good genome coverage, high specimen numbers). Based on previous research, apomictic Potentilla praecox F.W.Schultz has been chosen as a model to study the effect of mutation accumulation and its evolutionary consequences in a single presumably clonal population. Preliminary studies on the collection density over time identified one locality (Hohfluh, Switzerland) from which more than 100 specimens spanning the last 150 years are available in the central European herbaria. Such a comprehensive collection creates a unique opportunity to study a well-documented apomictic lineage in a timeframe beyond the standard field experiment. Hence, the project aims to test the following hypotheses: 1. Mutations accumulated over time are distributed unequally in the genome 2. Other phenomena enhancing the effect of the mutational load are active over short time scales. 3. Within last 150 year mutation accumulation led to extinction of particular lineages of P. praecox Additionaly, the results of the study might have an impact on conservation biology, by better understanding of past changes and guiding future conservation efforts in clonal lineages.

• DFG Programme: Research Grants