Limits on the evolution of tail ornamentation in birds
Limits on the evolution of tail ornamentation in birds
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DOI：
10.1086/381770
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发表时间：
2004-03-01
影响因子：
2.9
通讯作者：
Evans, MR
中科院分区：
文献类型：
--
作者：
Evans, MR
在鸟类中，细长的尾巴是最常见和研究最多的装饰品之一。不过，尾翼还具有空气动力学功能，起到转弯和慢速飞行的作用。如果一个尾巴是作为一个装饰品，那么将有一个不可避免的冲突之间的空气动力学的作用和信号的作用。空气动力学理论已经发展到可以预测不同尺寸和形状的装饰性尾翼的空气动力学和机械后果的程度。尾翼伸长将影响许多不同的机械和气动参数。对于这些参数中的至少一些并且可能全部，将存在由鸟的解剖学、形态学或生理学对尾部伸长的影响可以被容忍的程度设置的限制。例如，如果一个特定的尾巴形态意味着飞行所需的力量超过了飞行肌肉的力量，那么这种鸟显然无法用这样的尾巴飞行。为了检验这些考虑是否会限制装饰性尾翼的发展，研究了不同形状的长尾对三个参数的影响：静平衡、升阻比和飞行成本。所有这三个参数被发现限制了鸟类可能发展的尾巴形态的范围。这些限制对小鸟来说是最严重的，它们可能无法用任何形状的长尾巴进行操作。稍大一点的鸟可以长出细长的飘带和分叉的尾巴，但不能长出针尾或楔形的尾巴。中型到大型鸟类的限制较少，可以比小型鸟类发展更广泛的尾巴，但可以发展的尾饰的大小总是有限的。因此，自然界中观察到的一些自然现象可能是由自然现象对生态和行为的物理影响造成的。
In birds, elongated tails are one of the most common and most studied ornaments. However, the tail also has an aerodynamic function, playing a role in turning and slow flight. If a tail is to function as an ornament, then there will be an inevitable conflict between the aerodynamic role and the signaling role. Aerodynamic theory has developed to the point where it is possible to predict the aerodynamic and mechanical consequences of ornamental tails of different sizes and shapes. Tail elongation will influence many different mechanical and aerodynamic parameters. For at least some and possibly all of these parameters, there will be limits that are placed by the bird's anatomy, morphology, or physiology on the extent to which the effect of tail elongation could be tolerated. For example, if a particular tail morphology meant that the power required to fly exceeded the power available from the flight muscles, then the bird would obviously be unable to fly with such a tail. To examine whether these considerations could limit the development of ornamental tails, the effect of long tails of different shapes was examined on three parameters: static balance, lift-to-drag ratio, and the cost of flight. All three of these parameters were found to limit the range of possible tail morphologies that could be developed by birds. These limits were most acute for small birds, which may not be able to operate with a long tail of any shape. Slightly larger birds would be able to develop elongated streamers and forked tails but not pintails or wedge-shaped tails. Medium to large birds are less constrained and could develop a much wider range of tails than small birds, but there will always be limits to the sizes of tail ornament that could be developed. Thus the physical consequences of ornamentation on ecology and behavior are likely to be responsible for some of the patterns of ornamentation observed in nature.