DSSS - The hidden world of evolutionary novel genes

During evolution genes are continuously gained and lost, contributing to the adaptation of the organism to a changing environment. New genes can originate from already existing genes or gene parts, one prime mechanism being gene duplication followed by sequence divergence. But they can also arise de novo from previously non-genic parts of the genome. Recent studies indicate that de novo gene origination is much more prevalent than previously thought. For example, in humans, there are thousands of novel small proteins detected by ribosome profiling that have probably originated de novo. CRISPR-Cas9 screening indicates that, despite their recent origin, a large fraction of them are likely to be functional. De novo originated proteins have completely new sequences, and this might affect their early evolution and stability when compared to other types of proteins. To shed light into this question we have compared the evolutionary trajectories of recently formed duplicated and de novo genes, in yeasts and flies. We have found that, unexpectedly, both kinds of genes follow similar trajectories over time, with a peak of new genes at the species level, and much lower numbers in more ancestral branches. This implies that the majority of new genes that are important at the population level will tend to be lost at some point during the evolution of the species, leaving no traces in the conserved proteome. We will discuss the recent developments in the field of de novo gene birth and the challenges ahead.