Dominance hierarchies are generally established based on the levels of aggressiveness that animals present. Frequently, animals fight to establish a dominance hierarchy and obtain a disputed resource. The Mexican mojarra Cichlasoma istlanum is a native species of the Balsas river basin and coexists there with four nonnative cichlids: tilapia Oreochromis sp., convict cichlid Amatitlania nigrofasciata, spotcheek cichlid Thorichthys maculipinnis, and green terror Andinoacara rivulatus. These five cichlid species compete for spaces for reproduction, feeding, and shelter and frequently engage in aggressive interactions to obtain these resources. We quantified dominance indices to evaluate the hierarchical structure of dominance among these five cichlids and the duration of aggressive behaviors of the Mexican mojarra during experimental contests between the native species and each of the four nonnative species. The Mexican mojarra was consistently dominant over the other four cichlid species, performing a larger number of aggressive behaviors and investing more time in attacking than the nonnative cichlids, which resulted in a higher hierarchical position. Our results show that the native fish, Mexican mojarra, established dominance over all four nonnative cichlid fish of the Balsas basin. Thus, the establishment of nonnative cichlid species in the Balsas basin is likely associated with factors other than behavioral dominance.

中文翻译：

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巴尔萨斯盆地本地和非本地慈鲷的积极相互作用和优势等级的一致性

支配等级通常是根据动物表现出的攻击性水平建立的。动物经常为建立统治等级和获得有争议的资源而战。墨西哥 mojarra Cichlasoma istlanum是巴尔萨斯河流域的本土物种，并与四种非本土慈鲷共存：罗非鱼Oreochromis sp.、罪犯慈鲷Amatitlania nigrofasciata、斑点慈鲷Thorichthys maculipinnis和绿色恐怖Andinoacara rivulatus. 这五种慈鲷物种争夺繁殖、觅食和庇护的空间，并经常进行积极的互动以获取这些资源。我们量化优势指数以评估这五种慈鲷的优势等级结构以及墨西哥莫哈拉在本地物种与四种非本地物种之间的实验竞赛期间的攻击行为的持续时间。墨西哥 mojarra 在其他四种慈鲷物种中始终占主导地位，与非本地慈鲷相比，表现出更多的攻击行为并花费更多时间进行攻击，从而导致更高的等级地位。我们的研究结果表明，本地鱼类墨西哥 mojarra 在巴尔萨斯盆地的所有四种非本地慈鲷中确立了主导地位。因此，