Selection increased flight speed of fruit flies and wheel walking in mice

Results of long-term selection experiments. (a) Selection for an increase in flight speed of fruit flies. Speed was tested in a wind tunnel in which flies flew against the wind to reach a light source. (b) Selection for an increase in the amount of voluntary wheel walking done by mice.

[(a) Data from K. E. Weber, Genetics 144, 1996, 205–213, (b) Data from J. G. Swallow et al., Behav. Genet. 28, 1998, 227–237.]