Data from: Tadpole begging reveals high quality

Parents can benefit from allocating limited resources non-randomly among offspring, and offspring solicitation (i.e., begging) is often hypothesized to evolve because it contains information valuable to choosy parents. We tested the diagnostic predictions of three ‘honest begging’ hypotheses –Signal of Need, Signal of Quality, and Signal of Hunger – in the tadpoles of a terrestrial frog (Oophaga pumilio). In this frog, mothers provision tadpoles with trophic eggs, and when mothers visit, tadpoles perform a putative begging signal by stiffening their bodies and vibrating rapidly. We assessed the information content of intense tadpole begging with an experimental manipulation of tadpole condition (need/quality) and food-deprivation (hunger). This experiment revealed patterns consistent with the Signal of Quality hypothesis and directly counter to predictions of Signal of Need and Signal of Hunger. Begging effort and performance were higher in more developed and higher condition tadpoles and declined with food-deprivation. Free-living mothers were unlikely to feed tadpoles of a non-begging species experimentally cross-fostered with their own, and allocated larger meals to more developed tadpoles and those that vibrated at higher speed. Mother O. pumilio favour their high quality young, and because their concurrent offspring are reared in separate nurseries, must do so by making active allocation decisions. Our results suggest that these maternal choices are based at least in part on offspring signals, indicating that offspring solicitation can evolve to signal high quality.亲本可通过在子代间非随机分配有限资源而获益，子代乞食行为（begging）被广泛推测能够演化，原因在于其携带了对具有选择偏好的亲本极具价值的信息。本研究以陆生性蛙类箭毒蛙（Oophaga pumilio）的蝌蚪为研究对象，对三项“诚实乞食”假说的诊断性预测展开检验，这三项假说分别为：需求信号假说（Signal of Need）、质量信号假说（Signal of Quality）与饥饿信号假说（Signal of Hunger）。该蛙类的母体会以营养卵为蝌蚪提供食物；当母体到访抚育池时，蝌蚪会通过身体僵直并快速振动的方式呈现疑似乞食的信号行为。我们通过操控蝌蚪的身体状态（需求/质量）与食物剥夺程度（饥饿水平），评估了高强度蝌蚪乞食行为的信息含量。本实验结果与质量信号假说相符，却与需求信号假说和饥饿信号假说的预测直接相悖。发育程度更高、身体状态更佳的蝌蚪，其乞食投入与行为表现均更强，且该表现随食物剥夺程度的增加而下降。野生母体几乎不会对实验中与自身蝌蚪交叉寄养的非乞食物种蝌蚪进行投喂，且会向发育程度更高、振动速度更快的蝌蚪提供更多食物。箭毒蛙（Oophaga pumilio）的母体会偏好高质量子代，由于其同期繁育的子代被安置于不同抚育池内，因此母体必须通过主动的资源分配决策来实现这一偏好。本研究结果表明，这类母本选择至少部分基于子代发出的信号，这意味着子代乞食行为可演化出传递高质量个体信号的功能。