Summary of the increase in body size over time for experimental fish.

<p>(a) Illustration of the method used to estimate average family-based body size. A 1×1 mm grid was attached to the bottom of a standardized plastic container, where the water level was kept at 1.5 cm. Panels b and c show the average body size over time for lake and stream populations under either b) lake-like or c) stream-like food treatment. Dots represent the mean standard length (SL) of all families per source population (±1 SE).