Peters A, Denk A G, Delhey K, Kempenaers B
Reproductive Biology and Behaviour Group, Max-Planck Institute for Ornithology, Seewiesen, Starnberg, Germany.
J Evol Biol. 2004 Sep;17(5):1111-20. doi: 10.1111/j.1420-9101.2004.00743.x.
Female mate choice is often based on exaggerated sexual traits, signals of male qualities that females cannot assess directly. Two such key qualities are male immune and/or sexual competence, whereby honesty in signalling could be maintained by physiological trade-offs. Carotenoid-based ornaments likely constitute such honest signals, as there is direct competition for (limited) carotenoids between ornament deposition and anti-oxidant support of immune or sperm functioning. Using spectrometry, we assessed the potential signalling function of the yellow, carotenoid-based colour of the bill of male mallards, a target of female mate choice. Here we demonstrate that bill reflectance varied with plasma carotenoid level, indicating antioxidant reserves. Moreover, lower relative UV reflectance during autumn pairing predicted immune responsiveness and correlated positively with sperm velocity during breeding, a trait that affects fertility. Our data provide support for current theories that females could use carotenoid-based sexual signals to detect immune vigour and fertilizing ability of prospective mates.
雌性配偶选择通常基于夸张的性特征，这些特征是雌性无法直接评估的雄性品质信号。两个这样的关键品质是雄性的免疫能力和/或性能力，通过生理权衡可以维持信号传递的诚实性。基于类胡萝卜素的装饰可能构成这样的诚实信号，因为在装饰沉积与免疫或精子功能的抗氧化支持之间存在对（有限的）类胡萝卜素的直接竞争。我们使用光谱法评估了雄性绿头鸭喙部基于类胡萝卜素的黄色的潜在信号功能，绿头鸭是雌性配偶选择的对象。在这里，我们证明喙部反射率随血浆类胡萝卜素水平而变化，表明抗氧化储备。此外，秋季配对期间较低的相对紫外线反射率预示着免疫反应性，并与繁殖期间的精子速度呈正相关，精子速度是影响生育能力的一个特征。我们的数据为当前的理论提供了支持，即雌性可以利用基于类胡萝卜素的性信号来检测潜在配偶的免疫活力和受精能力。
