Female presence promotes male–male aggression among Tanichthys albonubes, a fish species without intense combat
2015
Nagaoka, Erika | Karino, Kenji
Males often compete with other males to acquire mates. When females are present, males of some animals are known to intensify their aggressive behavior against other males. However, studies demonstrating such male–male aggression in the presence of females have been conducted mainly among species with intense aggressive behavior, for example direct combat. In this study, we examined the effect of female presence on male–male aggressive behavior among fish of the species Tanichthys albonubes, among which intense male–male combat is not typically observed. When a female was present, two contesting males performed aggressive displays and chased each other more frequently than in absence of the female. Males also frequently fled from competitors when a female was present. In addition, when a female was present, differences between the aggressive behavior of two males were greater than when the female was absent, suggesting that the presence of females may emphasize male dominance. Irrespective of the female, large males chased small males more often, and small males more frequently fled contests. Inconsistent with theory, however, size-matched male pairs did not increase their aggressive behavior compared with size-mismatched male pairs in the absence or presence of a female.
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