least one other region. In no region was selection associated with a change in expression of >2-fold and in most cases, selection was associated with small changes in expression (<30%) among the genes included in the DE analyses (see above). The number of significantly DE genes, common to all three regions was small (N = 5) and the genes appear to have no common function(s). Only in the CeA, did the analyses reveal that the DE genes were associated with significant GO annotations (neuron part, structural constituent of myelin sheath and axon ensheathment). Among the genes in the neuron part category were several that have been implicated in excessive ethanol consumption, including Adora1, Crhr1, Gal, and Syt2 (Belfer et al., 2006; Enoch et al., 2013; Barbier et al., 2015; Clark et al., 2017). However, in the CeA as well as the SH and PL, the DE genes had on average a low intramodular connectivity, i.e., these genes were “leaf” nodes. This observation is consistent with the observation that the degree of DE was generally quite small and to detect such small changes requires that the variance for these genes must be relatively low. Connectivity requires sufficient variance to accurately detect
