Figure S1

Methods used to determine the offset between left and right valve data, illustrated with the population HAP_NANI-1. (A) Original data, before any offset is applied. As is typical for many cytheroids, right valves are smaller and more elongate than left valves. Note also that the sex ratios appear to differ between the sexes: most right valves are from the larger, male cluster, whereas the majority of left valves are females. This shifts the mean of right valves towards that of males, and the mean of left valves towards that of females. When valve means are used to determine left-right offsets (B), right valves are now systematically smaller and less elongate because the skewed sex ratios have resulted in an overcorrection for right valves away from male-like values. In contrast, fitting the mixture model while allowing left-right offsets to be freely optimized (C) provides a much better overlay of left and right valve data.