Multi-tasking as an ancient skill: When one gene does many things well.

Multi-tasking is in our DNA. Many genes perform more than one function, and the question is how well it can do them all. Pleiotropy is frequently considered to be an adaptive constraint that prevents optimal phenotypes from evolving because of antagonistic indirect selection acting on genetically correlated traits. However, as geneticists increasingly study the effects of genes under more realistic natural environments, even the most well studied genes are expressing fascinating pleiotropic effects. Pleiotropy appears to be utterly common. The genes involved in the regulation of flowering time in Arabidopsis thaliana, such as FLOWERING LOCUS C (FLC), offer case examples of such pleiotropy. Studying an ortholog of FLC in Arabis alpina, PERPETUAL FLOWERING 1 (PEP1), Hughes, Soppe and Albani (2019) present evidence that such pleiotropy in flowering-time genes persists through taxonomic diversification, albeit the precise function of the genes has evolved in response to taxon-specific natural selection. Their observation that trait-specific function can evolve even in highly pleiotropic genes suggests that pleiotropy may not constrain adaptation as much as is commonly assumed.