Neat FC, Huntingford FA, Beveridge MMC
Fish Biology Group, Division of Environmental & Evolutionary Biology, I.B.L.S., University of Glasgow
Anim Behav. 1998 Apr;55(4):883-91. doi: 10.1006/anbe.1997.0669.
In fights between animals over limited resources, the larger contestant often wins. Game theoretical models of animal fighting predict that relative body size is assessed during the fight and thus determines fight duration and intensity. In addition, if the contestants differ in the value they place on the disputed resource, this can also influence the outcome, duration and intensity of the fight. We studied territorial fighting in a cichlid fish, Tilapia zillii, in relation to relative body size and gonad weight. Relative gonad weight was a much stronger predictor of fight outcome than relative body size, even when body weight asymmetries were as large as 30%. This suggested that males with large gonads were fighting harder to defend their territory, perhaps because the value of a territory correlates with the gonadal state of the individual. A detailed analysis of mouth wrestling observed during fighting suggested that relative body size is assessed. However, contestants smaller than their opponent often continued to fight in spite of their size disadvantage. Weight disadvantaged winners appeared to fight more fiercely as suggested by a negative correlation between weight asymmetry and the proportion of bites inflicted by the winner. During escalated fighting, winners and losers differed consistently with regard to a behaviour termed mouth locking. Although neither biting nor persistence in mouth locking was related to gonad weight, we propose that the fish may have been assessing asymmetries unrelated to relative body size and possibly more related to levels of cost and the motivation to persist. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.
在动物为争夺有限资源而进行的争斗中，体型较大的竞争者往往会获胜。动物争斗的博弈论模型预测，在争斗过程中会评估相对体型大小，进而决定争斗的持续时间和强度。此外，如果竞争者对争议资源的重视程度不同，这也会影响争斗的结果、持续时间和强度。我们研究了丽鱼科鱼类齐氏罗非鱼的领地争斗与相对体型大小和性腺重量的关系。即使体重不对称高达30%，相对性腺重量对争斗结果的预测能力也远强于相对体型大小。这表明性腺大的雄性为保卫领地会更加拼命，也许是因为领地价值与个体的性腺状态相关。对争斗过程中观察到的口部扭打进行的详细分析表明，相对体型大小是会被评估的。然而，比对手体型小的竞争者尽管处于体型劣势，却常常继续争斗。体重处于劣势的获胜者似乎争斗得更激烈，体重不对称与获胜者造成撕咬的比例呈负相关就表明了这一点。在升级的争斗中，获胜者和失败者在一种名为口锁的行为方面始终存在差异。虽然撕咬和口锁的持续时间都与性腺重量无关，但我们认为，这些鱼可能一直在评估与相对体型大小无关的不对称性，可能更多地与代价水平和坚持争斗的动机有关。版权所有1998动物行为研究协会。版权所有1998动物行为研究协会。
