Ramos A, Gonçalves D
Institute of Science and Environment, University of Saint Joseph, Rua de Londres 16, Macao, China.
Front Zool. 2019 Aug 8;16:34. doi: 10.1186/s12983-019-0333-x. eCollection 2019.
In Southeast Asia, males of the Siamese fighting fish have been selected across centuries for paired-staged fights. During the selection process, matched for size males fight in a small tank until the contest is resolved. Breeders discard losing batches and reproduce winner batches with the aim of increasing fight performance. We assessed the results of this long-term selection process by comparing under standard laboratory conditions male and female aggressive behaviour of one strain selected for staged fights ("fighters") and one strain of wild-types. The aggressive response of adult fish was tested against their mirror image or a size-matched conspecific. Fighter males were more aggressive than wild-type males for all measured behaviours. Differences were not only quantitative but the pattern of fight display was also divergent. Fighter males had an overall higher swimming activity, performing frequent fast strikes in the direction of the intruder and displaying from a distance. Wild-type males were less active and exhibited aggressive displays mostly in close proximity to the stimuli. Females of the fighter strain, which are not used for fights, were also more aggressive than wild-type females. Aggressive behaviours were correlated across male and female fighter siblings, suggesting common genetic and physiological mechanisms to male and female aggression in this species. The study further shows that results were largely independent of the stimulus type, with the mirror test inducing similar and less variable responses than the live conspecific presentation. These results suggest that selection for male winners co-selected for high-frequency and metabolic demanding aggressive display in males and also enhanced female aggression, opening a wide range of testable hypothesis about the ultimate and proximate mechanisms of male and female aggression in .
在东南亚，暹罗斗鱼的雄性个体经过了数百年的筛选用于分阶段的配对打斗。在筛选过程中，体型相当的雄性斗鱼在一个小水箱中打斗，直至分出胜负。饲养者淘汰失败的批次，繁殖获胜的批次，目的是提高打斗表现。我们通过在标准实验室条件下比较一个为分阶段打斗而选育的品系（“斗士”）和一个野生型品系的雄性和雌性攻击行为，评估了这一长期筛选过程的结果。成年鱼的攻击反应是针对它们的镜像或体型相当的同种个体进行测试的。对于所有测量的行为，斗士雄性比野生型雄性更具攻击性。差异不仅体现在数量上，打斗表现的模式也有所不同。斗士雄性总体游泳活动水平更高，频繁朝着入侵者方向快速攻击，并在一定距离外展示。野生型雄性活动较少，大多在靠近刺激源的地方表现出攻击行为。不用于打斗的斗士品系雌性也比野生型雌性更具攻击性。斗士品系的雄性和雌性同胞之间的攻击行为存在相关性，这表明该物种中雄性和雌性攻击行为具有共同的遗传和生理机制。该研究还表明，结果在很大程度上与刺激类型无关，与活体同种个体呈现相比，镜像测试诱导出的反应相似且变异性更小。这些结果表明，对雄性获胜者的选择同时也选择了雄性中高频且消耗代谢的攻击展示，并且增强了雌性的攻击性，这为关于该物种中雄性和雌性攻击行为的终极和近端机制打开了一系列可测试的假设。
