Analysis of variation in lateral asymmetry of fiddler crabs Uca spp. and the ecological factors

雄性招潮蟹是一种Uca物种，有一只扩大的爪子，用于求偶挥手和打架。研究了乳沟蟹复合体和虎尾蟹复合体雄性大爪的利手和蟹的大小的变化。每个复合体的三个亚种也从形态上区分了原始爪子和再生爪子。物种间、亚种间和队列间的左撇子雄性比例的比较表明，UlalacTea复合体的比例在各个水平上都相当稳定。另一方面，在不同亚种中，左撇子雄鸟的比例存在显著差异。确定挥手求偶和打架求偶的代价，对于阐明维持左撇子和右撇子雄性比例的机制至关重要。在自然条件下，通过检测血糖和乳酸水平，估计了雄性攻击性和挥动爪子在中华绒螯蟹中的能量成本。使用不透明和透明围栏的围栏实验结果表明，招手展示招潮和争斗行为是耗费精力的。他们还与试图篡夺他们领土的陌生人作战。陌生人构成的威胁比邻居大得多，因为失去领土可能会危及生命。然而，与陌生人打架的时间比邻居之间的打架时间要短：这与人们普遍报道的“亲爱的敌人”现象相反。与邻居打架的时间比与陌生人打架的时间要长得多，但没有显示出力量测试中预测的模式。它们是根本不同的互动。我们认为，居民利用攻击性作为对侵占邻居的一种惩罚。

Males of fiddler crabs, Uca species, have a single enlarged claw used in courtship waving and fighting. The variation in handedness of the major claws and crab size were investigated for males of U.lactea complex and U.vocans complex. The original and regenerated claws were also distinguished morphologically for three subspecies of each complex. The comparisons in ratios of left-handed males between species, among subspecies, and among cohorts revealed that the ratio for U.lactea complex is quite stable at every level. On the other hand, a significant variation in ratio of left-handed males was detected among subspecies of U.vocans complex.Determining the costs of the courtship waving and fighting is critical to clarifying mechanisms that maintain the ratio of right-/left-handed males. The energy costs of male aggression and claw waving in a fiddler crab U.l.perplexa were estimated by examining blood glucose and lactate levels under natural conditions. The results of an enclosure experiment using opaque and transparent fences indicated that the waving display of the fiddler crab, as well as agonistic behavior, is energetically costly.The territorial males of U.l.perplexa fight their neighbours to demarcate and maintain territory boundaries. They also fight strangers that attempt to usurp their territories. Strangers pose a far greater threat than do neighbours since territory loss can be life threatening. Fights with strangers are, however, shorter than those between neighbours : the opposite of the commonly reported 'dear enemy' phenomenon. Fights with neighbours were significantly longer than those with strangers, but showed none of the patterns predicted for tests of strength. They were fundamentally different interactions. We argue that residents use aggression as a form of punishment against encroaching neighbours.