Flow cytometry YFP and CFP data and deep sequencing data of populations evolving in galactose Tomanek, Isabella ; https://orcid.org/0000-0001-6197-363X Guet, Calin C ; https://orcid.org/0000-0001-6220-2052 ddc:570 Copy-number and point mutations form the basis for most evolutionary novelty through the process of gene duplication and divergence. While a plethora of genomic sequence data reveals the long-term fate of diverging coding sequences and their cis-regulatory elements, little is known about the early dynamics around the duplication event itself. In microorganisms, selection for increased gene expression often drives the expansion of gene copy-number mutations, which serves as a crude adaptation, prior to divergence through refining point mutations. Using a simple synthetic genetic system that allows us to distinguish copy-number and point mutations, we study their early and transient adaptive dynamics in real-time in Escherichia coli. We find two qualitatively different routes of adaptation depending on the level of functional improvement selected for: In conditions of high gene expression demand, the two types of mutations occur as a combination. Under low gene expression demand, negative epistasis between the two types of mutations renders them mutually exclusive. Thus, owing to their higher frequency, adaptation is dominated by copy-number mutations. Ultimately, due to high rates of reversal and pleiotropic cost, copy-number mutations may not only serve as a crude and transient adaptation but also constrain sequence divergence over evolutionary time scales. Dryad 2022 info:eu-repo/semantics/other doc-type:other text http://purl.org/coar/resource_type/c_ddb1 https://research-explorer.ista.ac.at/record/12339 Tomanek I, Guet CC. Flow cytometry YFP and CFP data and deep sequencing data of populations evolving in galactose. 2022. doi:<a href="https://doi.org/10.5061/dryad.rfj6q57ds">10.5061/dryad.rfj6q57ds</a> info:eu-repo/semantics/altIdentifier/doi/10.5061/dryad.rfj6q57ds info:eu-repo/semantics/openAccess