Environmental heterogeneity is considered a general explanation for phenotypic
diversification, particularly when heterogeneity causes populations to diverge via local …

Building a genotype-phenotype-fitness map of adaptation is a central goal in evolutionary
biology. It is difficult even when adaptive mutations are known because it is hard to …

Experimental evolution is a method in which populations of organisms, often microbes, are
founded by one or more ancestors of known genotype and then propagated under …

Biased mutation spectra are pervasive, with wide variation in the magnitude of mutational
biases that influence genome evolution and adaptation. How do such diverse biases …

Evolutionary adaptation to a constant environment is driven by the accumulation of
mutations which can have a range of unrealized pleiotropic effects in other environments …

Historical contingency and diminishing returns epistasis have been typically studied for
relatively divergent genotypes and/or over long evolutionary timescales. Here, we use …

Epistasis is caused by genetic interactions among mutations that affect fitness. To
characterize properties and potential mechanisms of epistasis, we engineered eight double …

The ability to design synthetic genes and engineer biological systems at the genome scale
opens new means by which to characterize phenotypic states and the responses of …

Modifications to transcriptional regulators play a major role in adaptation. Here, we
compared the effects of multiple beneficial mutations within and between Escherichia coli …

Microbial evolution experiments provide a powerful tool to unravel the molecular basis of
adaptive evolution but their outcomes can be difficult to interpret, unless the selective forces …