Handicap principle implies emergence of dimorphic ornaments

Species spanning the animal kingdom have evolved extravagant and costly ornaments to attract mating partners. Zahavi's handicap principle offers an elegant explanation for this: ornaments signal individual quality, and must be costly to ensure honest signalling, making mate selection more efficient. Here, we incorporate the assumptions of the handicap principle into a mathematical model and show that they are sufficient to explain the heretofore puzzling observation of bimodally distributed ornament sizes in a variety of species.

动物界中形形色色的物种演化出了华丽且代价高昂的装饰性特征，以吸引交配伴侣。扎哈维的累赘原理（handicap principle）为此提供了简洁优雅的解释：装饰性特征是个体品质的信号，且必须具备代价才能确保信号的诚实性，从而提升配偶选择的效率。本文将累赘原理的假设纳入数学模型，结果表明这些假设足以解释此前在多种物种中观察到的装饰性特征尺寸呈双峰分布这一令人困惑的现象。