Hasegawa Masaru
Department of Environmental Science Ishikawa Prefectural University Nonoichi Ishikawa Japan.
Ecol Evol. 2024 Jan 14;14(1):e10850. doi: 10.1002/ece3.10850. eCollection 2024 Jan.
The cost of ornamentation is often measured experimentally to study the relative importance of sexual and viability selection for ornamentation, but these experiments can lead to a misleading conclusion when compensatory trait is ignored. For example, a classic experiment on the outermost tail feathers in the barn swallow explains that the concave (or U-shaped) aerodynamic performance cost of the outermost tail feathers would be the evolutionary outcome through viability selection for optimal tail length, but this conclusion depends on the assumption that compensatory traits do not cause reduced performance. Using a simple "toy model" experiment, I demonstrated that ornamentation evolved purely though sexual selection can produce a concave cost function under the presence of compensatory traits, which was further reinforced by a simple mathematical model. Therefore, concave cost function (and the low performance of individuals with reduced ornaments) cannot be used to infer the evolutionary force favoring ornamentation, due to a previously overlooked concept, "overcompensation," which can worsen the whole body performance.
人们常常通过实验来衡量装饰的成本，以研究性选择和生存选择对装饰的相对重要性，但当忽略补偿性性状时，这些实验可能会得出误导性的结论。例如，一项关于家燕最外侧尾羽的经典实验表明，最外侧尾羽的凹形（或U形）空气动力学性能成本将是通过对最佳尾长的生存选择而产生的进化结果，但这一结论取决于补偿性性状不会导致性能下降的假设。通过一个简单的“玩具模型”实验，我证明了在存在补偿性性状的情况下，纯粹通过性选择进化而来的装饰可以产生一个凹形成本函数，这一点通过一个简单的数学模型得到了进一步强化。因此，凹形成本函数（以及装饰减少的个体的低性能）不能用于推断有利于装饰的进化力量，因为一个先前被忽视的概念“过度补偿”会使整体性能恶化。
