Figure 2From: Insights into the role of differential gene expression on the ecological adaptation of the snail Littorina saxatilisDetermination of the optimal number of reference genes for data normalization. Bar values indicate the magnitude of change in the normalization factor after the inclusion of an additional reference gene. GeNorm authors' suggest that V > 0.15 should be considered as the threshold to include an extra reference gene into the assay.Back to article page