Fig. 4

Differences in variance of expression of gene models in the eggs from different crosses in relation to maternal embryonic heat stress. Frequency of log₁₀(CV²_H/CV²_C) values of gene models in eggs from individuals heat treated as embryos (H) divided by values from control individuals (C) in (a), BB conspecific cross, and (b), AB hybrid cross. In (c), ABB cross, the heat shock (H) had been administered to the embryo that became the AB mother of the individual producing the eggs. For each gene model the value of eggs from heat stressed individuals was divided by the corresponding value of the eggs from the same lineage but without heat shock. Red dotted lines indicate a log ratio of zero (CV² values equal). d-g Distribution of genes (coloured dots) showing more than five times increase (shown in red in d, in purple in f) or decrease (shown in blue in e, shown in dark green in g) in CV² between eggs from a heat-treated and a control individual in AB (d, e) or between eggs from an individual with a heat-treated mother and one with a control mother in ABB (f-g). X-axis shows average expression level (TPM) in eggs from control (C) mother, and y-axis average expression level (TPM) from heat-shocked (H) mother in each batch. Note that the genes showing a five-fold increase or decrease of CV.² were not limited to genes with low expression levels. ABC (n = 37 eggs); ABH (n = 36); ABCB (n = 32); ABHB (n = 43)