Fig. 5.

Species-specific distributions of oxytocin-like binding sites reflect evolutionary convergence and divergence in flocking and territoriality. (A–C) Representative autoradiograms of ¹²⁵I-OT antagonist binding sites in the caudal LS (LSc) in two sympatric, congeneric finches – the territorial violet-eared waxbill (A) and the gregarious Angolan blue waxbill (B), plus the highly gregarious zebra finch (C). (D) Densities of binding sites in the dorsal (pallial) LSc of two territorial species (Melba finch, MF, and violet-eared waxbill, VEW), a moderately gregarious species (Angolan blue waxbill, ABW), and two highly gregarious species (spice finch, SF, and zebra finch, ZF). No sex differences are observed and sexes were pooled. Total n = 23. Different letters above the boxes denote significant species differences (Mann-Whitney P < 0.05) following significant Kruskal-Wallis. (E) Binding densities tend to reverse in the subpallial LSc (P = 0.06), suggesting that species differences in sociality are most closely associated with the relative densities of binding sites along a dorso-ventral gradient, as confirmed in the bottom panel (F) using a dorsal:ventral ratio. Abbreviations: Hp, hippocampus; LSc.d, dorsal zone of the LSc; LSc.v,vl, ventral and ventrolateral zones of the LSc; N, nidopallium; PLH, posterolateral hypothalamus; TeO, optic tectum. Modified from Goodson et al. (2009d).