Effects of a Female Audience on Male Aggression in Siamese Fighting Fish, Beta splendens Dan Rauch 12-4-01 ANSC 455

Males perform behaviors to gain attention of females Linked to reproduction and natural selection Prove potency and vigor of genetic material Competition for the right to reproduce between males Examine the effects a female audience has on aggression between males

Methods: 12 male Beta splendens selected randomly from subjects 2 female Beta splendens selected for audience Stage I: Male presented with mirror for 5 minutes Tank with algae and water on opposite side Stage II: Male still presented with mirror for 5 minutes Algae tank replaced with tank of female A Stage III: Tank with female A replaced with algae tank

Four display behaviors are recorded in each stage: BS – Broadside display Perpendicular position to mirror with fins extened FD – Frontal display Facing mirror with gills and pectoral fins extended TS – Tail swish Tail is beat to push water in the direction of image BA – Bite attempt Attacking of reflected image with mouth

Same female was used for all experiments to maintain consistency of reaction to reproductive status Data from males who did not display during a stage was discarded subject KK15 was removed Control: 6 randomly selected males Subjected to mirror for 15 minutes with behaviors grouped in 5 minute intervals Compare with experimental data for warm-up effect

Results: Number of displays increased when female was introduced 5 subjects had 1-5 display increase in Stage II 5 subjects doubled Stage I displays 1 subject tripled number of displays Types of behaviors changed with introduction of female, but varied between individuals

Controls:

Experimental group vs Control group Average number of displays Subjects Control Stage I 26.5 21.0 Stage II 39.6 17.0 Stage III 27.8 17.3

Conclusion: Female audience may increase the intensity and number of displays of male aggression There was not an apparent warm up effect in displaying males