Fig. 4. Study II: gonadotropin-releasing hormone 1 (GnRH1) gene expression increases within 3 days following removal of suppressive tactile cues from dominant conspecifics. Mean GnRH1 mRNA levels (A), plotted as normalized optical density (see Materials and methods), and gonosomatic indices (GSIs) (B) are plotted for males undergoing a 3- or 7-day transition from non-territorial (NT) to territorial (T) and are compared with those of the NT and T males of stable social status (2 weeks) from study I. Values are means + S.E.M. (N=6 NT, 8T for 3- and for 7-day transmissions; N=6 NT, 5 T for >2 weeks). Open columns show control NT values. Filled columns show NTT and undisturbed T male values. (C) Gonad size, plotted as the gonosomatic index (GSI; see Materials and methods) and GnRH1 gene expression (plotted as normalized optical density) are positively correlated. The strength of the correlation (Spearman ) increased with the time spent in the T state. Asterisks indicate P-values: ^*P<0.05; ^**P<0.0005.

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