Percy FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, Department of Biological Sciences, University of Cape Town, Rondebosch, Cape Town, 7701, South Africa.
Ecol Lett. 2016 Jun;19(6):679-86. doi: 10.1111/ele.12606. Epub 2016 May 2.
Detectability of different colour morphs under varying light conditions has been proposed as an important driver in the maintenance of colour polymorphism via disruptive selection. To date, no studies have tested whether different morphs have selective advantages under differing light conditions. We tested this hypothesis in the black sparrowhawk, a polymorphic raptor exhibiting a discrete white and dark morph, and found that prey provisioning rates differ between the morphs depending on light condition. Dark morphs delivered more prey in lower light conditions, while white morphs provided more prey in brighter conditions. We found support for the role of breeding season light level in explaining the clinal pattern of variation in morph ratio across the species range throughout South Africa. Our results provide the first empirical evidence supporting the hypothesis that polymorphism in a species, and the spatial structuring of morphs across its distribution, may be driven by differential selective advantage via improved crypsis, under varying light conditions.
不同颜色形态在不同光照条件下的可检测性被认为是通过非连续性选择来维持颜色多态性的一个重要驱动因素。迄今为止，还没有研究测试不同形态在不同光照条件下是否具有选择优势。我们在黑色雀鹰中检验了这一假设，这是一种表现出明显白色和深色形态的多态猛禽，结果发现，形态之间的猎物提供率因光照条件而异。深色形态在光照较弱的情况下提供更多的猎物，而白色形态在光照较强的情况下提供更多的猎物。我们发现，繁殖季节光照水平在解释南非整个物种范围内形态比例的渐变模式方面具有重要作用。我们的研究结果为以下假设提供了第一个经验证据，即在物种的多态性以及形态在其分布范围内的空间结构可能是由在不同光照条件下通过改善伪装而产生的差异选择优势所驱动的。
