Leonie Johanna Jahn

Project title

EVOLOOP: untangling phenotype, epigenetics and genetic feedback mechanisms in environmental adaptation

What is your project about?

Why does life on Earth look and behave the way it does? This is one of the most fundamental questions in biology, addressed by evolutionary theory. Currently, we assume that genetic variation, the raw material for evolution, arises largely through random mutations and genomic rearrangements, while natural selection determines which variants persist. We also know that many organisms can adapt to environmental change in the short term through changes in gene expression, mediated by epigenetics, the molecular mechanisms that regulate gene activity without changing the DNA sequence itself. Recently, some epigenetic modifications have been shown to affect where and how often mutations and genomic rearrangements occur. I will test whether environmental conditions can, through these mechanisms, bias genetic adaptation, making it not entirely random but environmentally guided. Using the filamentous fungus Aspergillus flavus and its domesticated form Aspergillus oryzae, I will combine laboratory evolution experiments with analyses of real-world populations to uncover how environments shape genetic adaptation.

How did you become interested in your particular field of research?

From an early age, I have felt a strong connection to nature and a desire to understand life better. This curiosity led me to study biology, where I became particularly interested in epigenetics, as it links the external environment with the internal being, connecting ecology, evolution, and genetics. Alongside fundamental questions, I have also been motivated by applied research that addresses societal challenges. For example, during my PhD, I studied the evolution of antibiotic resistance and how understanding these processes can inform better treatment strategies. Since then, I shifted my focus toward climate change and learned that our food system is the single most important driver of planetary and human health. This led me to work with Aspergillus oryzae, an important organism in traditional fermentation and food innovation. This project therefore combines my interest in fundamental evolutionary biology with applications in sustainable food systems.

What are the scientific challenges and perspectives in your project?

A key challenge in studying evolution is that different approaches each have limitations. Laboratory evolution experiments allow precise control over environmental conditions and selective pressures, but they are typically restricted to short timescales, making it unclear how well they reflect long-term evolutionary processes in nature. In contrast, studying natural populations captures real evolutionary outcomes, but the historical and environmental forces shaping them are often unknown and difficult to reconstruct.      

My model system helps bridge this gap. It consists of a fast-growing microorganism with a short generation time that can be evolved and genetically manipulated in the laboratory, allowing causal mechanisms to be tested directly. In parallel, domesticated populations of Aspergillus oryzae provide a unique record of evolution under partially known and human-influenced conditions over hundreds of years. Together, this enables direct comparison between controlled experiments and real-world evolutionary histories. This integrated approach offers the opportunity to validate experimental findings in natural contexts. This offers the perspective to test theoretical hypothesis proposed by the extended modern synthesis of evolutionary more robustly to refine our understanding of evolutionary theory.

What is your estimate of the impact, which your project may have to society in the long term?

If this project demonstrates that environmental conditions can influence genetic adaptation through epigenetic mechanisms in both laboratory and real-world settings, it would improve our ability to predict the emergence and adaptation of Aspergillus flavus as a plant and human pathogen. In addition, this knowledge could be used to guide the development of novel starter cultures with improved traits for fermentation and other applications relevant to the green transition. Finally, validating these findings in additional model systems would help determine how general these mechanisms are, potentially contributing to a more refined understanding of evolutionary theory.

Which impact do you expect the Sapere Aude programme will have on your career as a researcher?

It is a great honor for me to have received a Sapere Aude grant. I also see it as recognition of the work already carried out leading up to this project, not only by me but also by current and former members of my group, my mentors, our collaboration partners and my research environment. The grant provides an important opportunity to further develop, refine, and strengthen my independent research profile. I hope it will lead not only to scientific advances in Aspergillus flavus/oryzae biology, new approaches to developing starter cultures, and contributions to a more refined understanding of evolutionary theory, but also to new networks, collaborations, career opportunities for my team members, new ideas, and future projects.