Fig. 2

Overall change in geotaxis score after 15 generations of selection. Y1 male geotaxis score (filled circle) increased significantly after selection, while Y25 male geotaxis score (filled square) did not. No overall change in Y1 female (open circle) or Y25 female (open square) was detected. Sex-specific significant differences between Y1 and Y25 geotaxis scores are marked by an asterisk and based on t-tests adjusted for multiple comparisons (k = 2). Data points represent the grand means of each sex-specific treatment (n = 3) and error bars represent standard errors. See methods for LS grand means calculation