Fig. 1

C. elegans differences in a phoretic behavior map to chromosome IV. a The mean nictation fractions of 12 divergent wild isolates are shown (from left, CB4856 (blue), EG4725, ED3017, JT11398, N2 (orange), JU258, JU775, DL238, LKC34, CX11314, MY16, and MY23). Twenty-four replicates of CB4856 and three replicates of all other strains were measured to calculate the means. Error bars are standard deviations. b A histogram of the normalized nictation fractions of 186 N2xCB4856 recombinant inbred advanced intercross lines (RIAILs) is shown. c Linkage-mapping results of normalized nictation fraction are shown with genomic position (Mb) on the x-axis and logarithm of odds (LOD) score on the y-axis. The tick marks on the x-axis denote every 5 Mb. Each chromosome is in its own box labeled on top. The gray line is the LOD threshold for 5% genome-wide error rate obtained by permuting the phenotype data and mapping 1000 times. The red triangle denotes the peak QTL marker. d Tukey box plots of N2 (orange) and CB4856 (blue) are shown with data points plotted behind. The horizontal line in the middle of the box is the median, and the box denotes the 25th to 75th quantiles of the data. The vertical line represents the 1.5 interquartile range