Bar graphs showing the mean dominance indices (DI) as a function of time.

<p>The results shown are: before visual exposure (control) and after visual exposure for three groups of animals up to 1 day (A), up to 3 days (B) and up to 7 days (C). Seeing aggressive acts by the larger conspecific male continuously suppressed the dominant behavior of the subjects. The subjects had decreased dominance indices one hour after seeing the aggressive stimuli in all three groups. The solid bars are subjects that were exposed visually to the larger stimulus male and the hatched bars are control subjects that saw no other fish. Mean values with letters are significantly different from corresponding mean values without letters. The standard errors (SE) of means are shown as error bars.</p

PCR Primers for <i>A. burtoni</i> target genes used in this study

<p>PCR Primers for <i>A. burtoni</i> target genes used in this study</p

Sketch showing the aquarium used for the behavioral paradigm.

<p>An experimental tank (45l.) was divided in half with a watertight, clear divider (gray mid-line) and a removable opaque barrier (black mid-line). The small male fish in the left compartment is the subject and the large male fish (∼ 4 times larger) in the right compartment is the stimulus. A half terra cotta pot was cut in half and placed so that both the stimulus and subject “shared” the same shelter (dark curve). Note that this “shared” shelter was hemisected by both center dividers. A layer of gravel covered the bottom of the tank and the dotted lines identify three zones in each compartment used to record animal position.</p

The CRF, CRFBP, CRF-R1 and CRF-R2 expression levels were significantly correlated with the dominance index (DI).

<p>(A) CRF and (B) CRF-R2 expression in the brains of experimental subjects was correlated with aggression (r = −0.562 and −0.584, <i>p</i>≤0.001, n = 29). (C) The total CRFBP expression levels were related to DI regardless of the visual experience (r = −0.278, <i>p</i> = 0.0347, n = 58). (D) In the control subjects, the CRF-R1 expression in the brain was related to dominance indices (r = 0.469, <i>p</i> = 0.0137, n = 27) and viewing the large conspecific male visually diminished this effect. The black dots represent the subjects, and the white dots represent the controls.</p

Brain gene expression levels were influenced by the visual stimulus after 3 days of exposure.

<p>Expression of stress related mRNAs, including CRF (A), CRFBP (B) and AVT (E) changed significantly. (C) CRF-R1 expression levels decreased following onset of visual threats, but (D) CRF-R2 expression levels increased. (F–H) Expression of the three GnRH mRNA levels increased following onset of visual threats at day 3. Means with superscript letters are significantly different from those without letters. Error bars show the standard error of the mean.</p

Circulating 11-KT concentrations were influenced by visual information and were correlated with dominant behaviors.

<p>(<b>A</b>) The circulating 11-KT concentrations were suppressed in the first 24 hours by the stimulus, and increased after 3 days in the new environment. The bars show the mean 11-KT (± SE) of the subjects (solid) and the controls (hatched) at day 1 (D1), day 3 (D3) and day 7 (D7). (<b>B</b>) The mean DI (± SE) as a function of groups. D1: Day 1 group; D3: Day3 group; D7: Day7 group. Means with no common superscript letters are significantly different. The standard errors of means are shown as error bars. (<b>C</b>) The DI was positively correlated with plasma 11-KT levels (r = 0.509, <i>p</i><0.001, n = 58). The black dots represent the subjects, and the white dots represent the controls.</p

Seeing the larger conspecific male caused the subject to abandon his territory in the shelter.

<p>(<b>A</b>) The subjects reduced visits to the pot shelter (F_{(1, 380)} = 13.535, <i>p</i><0.001) and (<b>B</b>) reduced the percentage of time spent in the pot zone out of total observation time (F_{(1, 370)} = 8.399, <i>p</i> = 0.004). Means with superscript letters are significantly different from those without letters. Error bars are the standard errors of means.</p

The frequency of aggressive behaviors was correlated with androgen concentrations in the plasma.

<p>The x-axis shows the frequency of all aggressive behaviors (chasing and border display). The T concentrations are shown on the left y-axis and were positively correlated with aggression (black circle; solid regression line; r = 0.384, <i>p</i> = 0.0438, n = 28). The 11-KT levels are shown on the right y-axis and were also positively correlated with aggression (gray triangles; dotted regression line; r = 0.506, <i>p</i> = 0.027, n = 19).</p

Overt aggressive acts.

<p>Number of overt aggressive acts (biting and ramming) displayed by signaling males in the presence of different audiences. The number of over aggressive acts varied across all audience types and the letters above the bars represent significant differences at α = 0.05. Differences in the number of aggressive acts performed in the presence of a group of females, size-matched males or smaller males did not differ from the control condition.</p

Correlations between auditory evoked potential hearing threshold, circulating sex steroid levels, and gonadosomatic index (GSI) in the African cichlid fish <i>Astatotilapia burtoni</i>.

<p>11-KT, 11-ketotestosterone; E₂, 17β-estradiol; T, testosterone; <i>r</i>, correlation coefficient; <i>p</i><0.05 are in bold.</p