Figure 3: Variation in longevity within labs for each replicate plate for eight natural isolates of C. briggsae.

It is noteworthy that in many cases a given natural isolate tends to display distinct patterns of responses under identical laboratory conditions rather than a continuous distribution of ‘error’ among replicates. Among-replicate variation within each lab was a much larger barrier to reproducibility than variation in the average response of a strain across labs (Table 2). Each plate was initiated with n=35 animals.