Host virus coevolution – demography versus selection in the face of multiple stressors

• Applicant: Professor Dr. Lutz Becks
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: from 2015 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 274696124

There is a continuing interest to characterise the pace of adaptive evolution and a need for a better understanding of the factors influencing the rate of evolution. Especially, we lack a detailed understanding on how evolutionary dynamics at the genomic level relate to the distribution of fitness in populations evolving together in complex environments. In the project proposed here, we aim to identify rapid adaptive genomic changes in coevolving host-virus populations and to determine how multiple stressors for the host and virus alter the rate and trajectory of rapid adaptation. In previous experiments combined with genomic analyses we showed how demographic changes of host and coevolution between the host and virus affected adaptive changes at the genome level of both, host and virus. Using the same experimental system and the bioinformatics tools developed in the previous project, we now aim testing the hypothesis that abiotic stressors and species interactions interactively affect the pace of adaptive evolution. We will follow the dynamics of changes across time at multiple levels, i.e. population dynamics, phenotypic and genomic changes and characterise observed changes across a few hundred (840) algae clones in detail at the phenotype level (time shift experiments) and at the genome level (genome-wide associations). We will explicitly test if additional abiotic stressors for virus and/or host will alter the coevolutionary dynamics directly (i) through altering the strength and directionality of selection, (ii) through interactions between different individuals (clonal interference), (iii) through interactions within the genome (pleitropy, epistasis), or (iv) indirectly through demographic changes. Overall we will identify if and how environmental complexity introduced by abiotic stressors constrains the pace of resistance evolution even when the mutation rate is high.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1819: Rapid evolutionary adaptation: Potential and constraints
• International Connection: Switzerland
• Co-Investigator: Dr. Philine Feulner
• Cooperation Partners: Dr. Sven Künzel; Professor Dr. Daniel Wegmann