No mutual mate choice for quality in zebra finches: time to question a widely-held assumption

Studies of mate choice typically assume that individuals prefer high quality mates and select them based on condition-dependent indicator traits. In species with bi-parental care, mutual mate choice is expected to result in assortative mating for quality. When assortment is not perfect, the lower quality pair members are expected to compensate by increased parental investment to secure their partner (positive differential allocation). This framework has been assumed to hold for monogamous species like the zebra finch (Taeniopygia guttata), but progress has been hampered by the difficulty to define individual quality. By combining multiple measures of causes (inbreeding, early nutrition) and consequences (ornaments, displays, fitness components) of variation in quality into a single principal component, we here show that quality variation can be quantified successfully. We further show that variation in quality indeed predicts individual pairing success, presumably because it reflects an...

配偶选择（mate choice）领域的经典研究通常假定，个体偏好高质量配偶，并基于依赖于个体状态的指示性状完成择偶筛选。在存在双亲抚育（bi-parental care）的物种中，双向配偶选择（mutual mate choice）理论上会导致基于个体质量的选型交配（assortative mating）。当交配配对的选型性未达完美时，质量较低的配偶个体可通过提升双亲抚育投入弥补自身劣势，以稳固伴侣联结，该策略被称为正向差异投入（positive differential allocation）。这一理论框架曾被认为适用于斑胸草雀（Taeniopygia guttata）等单配制物种，但相关研究进展长期受限于个体质量难以准确定义的难题。本研究将个体质量变异的多项成因指标（近交程度、早期营养状况）与多项结果指标（装饰性状、展示行为、适合度组分（fitness components））整合为单一主成分（principal component），成功实现了个体质量变异的有效量化。研究进一步证实，个体质量变异确实能够预测个体的配对成功率，推测其原因在于质量变异反映了……