Population size shapes trade-off dilution and adaptation to a marginal niche unconstrained by sympatric habitual conditions

How does niche expansion occur when the habitual (high-productivity) and marginal (low-productivity) niches are simultaneously available? Without spatial structuring, such conditions should impose fitness maintenance in the former while adapting to the latter. Hence, adaptation to a given marginal niche should be influenced by the identity of the simultaneously available habitual niche. This hypothesis remains untested. Similarly, it is unknown if larger populations, which can access greater variation and undergo more efficient selection, are generally better at niche expansion. We tested these hypotheses using a large-scale evolution experiment with Escherichia coli. While we observed widespread niche expansion, larger populations consistently adapted to a greater extent to both marginal and habitual niches. Owing to diverse selection pressures in different habitual niches (constant versus fluctuating environments; environmental fluctuations varying in both predictability and speed), f..., This data was collected on laboratory populations of E. coli subjected to experimental evolution., , # Population size shapes trade-off dilution and adaptation to a marginal niche unconstrained by sympatric habitual conditions

The dataset consists of an .xlsx file with six tabs, as described below.

## Description of the data and file structure

We founded E. coli MG1655 populations from a single common ancestral clone and cultured them in eight different environmental conditions at two distinct population sizes, large (L) and small (S). All eight environments offered Acetate as the low productivity carbon source that constituted the marginal niche. Out of the eight environments, four offered a single distinct high productivity carbon source (constant habitual niche) for bacterial growth (one of thymidine (Thy), galactose (Gal), sorbitol (Sor) or arabinose (Ara)). In the other four environments, the habitual niche (high productivity carbon source) fluctuated over time in all combinations of predictable versus unpredictable and fast (switching every ~13.3 generations) versus slow (sw...