Martínez-Padilla Jesús, Dixon Heather, Vergara Pablo, Pérez-Rodríguez Lorenzo, Fargallo Juan A
Aberdeen Centre for Environmental Sustainability (ACES), University of Aberdeen & The Macaulay Institute, School of Biological Sciences, Tillydrone Avenue, Aberdeen, UK.
Naturwissenschaften. 2010 May;97(5):469-77. doi: 10.1007/s00114-010-0660-4. Epub 2010 Mar 23.
How colouration provides information about individuals in birds has been a central issue in recent decades. Although much information has been derived, little is known about the adaptive significance of egg colouration in birds. A recent idea suggests that biliverdin- and porphyrin-pigmented eggs may act as a post-mating sexual signal for males to assess female quality. In birds, it is common for males to influence prelaying female condition by courtship feeding. Using Eurasian kestrels, a species that lays protoporphyrin-pigmented eggs, we descriptively assessed the influence of male feeding on egg pigmentation by considering female phenotype, condition, breeding parameters and male body condition. We found that older females and females with greyer tails (an index of individual quality) produce highly pigmented eggs. However, male body condition was the only variable that explained egg colouration when considered together with the female-related variables. Therefore, females that mated with males in better condition laid highly pigmented eggs. With the same species, we also explored the cost of producing protoporphyrin-pigmented eggs using a food-supply experiment before the laying period. Food supplementation did not increase egg pigmentation, but hatching success and egg mass were positively related to egg colouration only in food supplied pairs. We suggest that egg colouration might be costly to produce and probably suggests egg quality. However, this cost cannot be explained by female quality, but by male condition instead. In general, our results do not support the theory that egg colouration is a post-mating sexual signal in species where males determine female condition at the time of laying.
近几十年来，鸟类的羽色如何为个体提供信息一直是核心问题。尽管已获取了大量信息，但对于鸟类卵色的适应性意义却知之甚少。最近有一种观点认为，含有胆绿素和卟啉色素的卵可能作为一种交配后的性信号，供雄性评估雌性质量。在鸟类中，雄性通过求偶喂食来影响雌性产卵前的状态是很常见的。我们以欧亚红隼为研究对象，该物种产含原卟啉色素的卵，通过考虑雌性表型、状态、繁殖参数和雄性身体状况，我们描述性地评估了雄性喂食对卵色素沉着的影响。我们发现，年龄较大的雌性以及尾巴颜色较灰（个体质量指标）的雌性会产出色素沉着较高的卵。然而，在与雌性相关变量一同考虑时，雄性身体状况是唯一能解释卵色的变量。因此，与身体状况较好的雄性交配的雌性会产出色素沉着较高的卵。对于同一物种，我们还在产卵期前通过食物供应实验探究了产出含原卟啉色素的卵的成本。食物补充并未增加卵的色素沉着，但仅在提供食物的配对中，孵化成功率和卵重与卵色呈正相关。我们认为，产生卵色可能成本高昂，且可能暗示卵的质量。然而，这种成本无法用雌性质量来解释，而应由雄性状况来解释。总体而言，我们的结果并不支持卵色是雄性在产卵时决定雌性状况的物种中交配后的性信号这一理论。
