Distributions of the orthologous gene groups containing duplicate genes that arose through 3R-WGD (shown as gray boxes) in the network diagrams. Panels A-D: long-term potentiation (LTP), taste transduction (TT), olfactory transduction (OT), and tricarboxylic acid cycle (TCA), respectively. White boxes denote orthologous gene groups with no 3R-WGD-derived duplicates (1:1 orthologous relationship between tetrapods and teleosts). Dashed boxes denote gene groups in which no clear orthologous relationship was identified between tetrapods and teleosts. The network schemes of the LTP, TT, OT, and TCA are based on knowledge in human summarized in KEGG pathway database .