The paradoxical presence of toxic chemical compounds in ripe fruits represents a balance between plant enemies and allies: chemical traits can defend seeds against antagonistic herbivores, seed predators or fungal pathogens, but also can impose costs by repelling mutualistic seed dispersers, although the costs are often difficult to quantify. Seeds gain fitness benefits from travelling far from the parent plant, as they can escape from parental competition and elude specialized herbivores as well as pathogens that accumulate on adult plants. However, seeds are difficult to follow from their parent plant to their final destination. Thus, little is known about the factors that determine seed dispersal distance. We investigated this potential cost of fruit secondary compounds - reduced seed dispersal distance - by combining two datasets from previous work on a Neotropical bat-plant dispersal system (bats in the genus Carollia and plants in the genus Piper). We used data from captive behavioral experiments, which show how amides in ripe fruits of Piper decrease the retention time of seeds and alter food choices. With new analyses, we show that these defensive secondary compounds also delay the time of fruit removal. Next, with a behaviorally annotated bat telemetry dataset, we quantified post-feeding movements (i.e. seed dispersal distances). Using generalized additive mixed models we found that seed dispersal distances varied nonlinearly with gut retention times as well as with the time of fruit removal. By interrogating the model predictions, we identified two novel mechanisms by which fruit secondary compounds can impose costs in terms of decreased seed dispersal distances: 1) small scale reductions in gut retention time and 2) causing fruits to forgo advantageous bat activity peaks that confer high seed dispersal distances.

中文翻译：

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防御性水果代谢物通过在多个时间尺度上改变蝙蝠的行为和生理机能来阻碍种子传播

成熟果实中有毒化合物的矛盾存在代表了植物敌人和盟友之间的平衡：化学特性可以保护种子免受敌对食草动物、种子捕食者或真菌病原体的侵害，但也可以通过排斥互惠种子传播者来增加成本，尽管成本通常很高难以量化。种子通过远离亲本植物而获得健康益处，因为它们可以逃避亲本竞争并避开专门的食草动物以及积累在成年植物上的病原体。然而，种子很难从它们的亲本植物追踪到它们的最终目的地。因此，关于决定种子传播距离的因素知之甚少。我们通过结合以前在新热带蝙蝠-植物传播系统（Carollia 属的蝙蝠和 Piper 属的植物）上工作的两个数据集，研究了果实次生化合物的这种潜在成本 - 减少了种子传播距离。我们使用了来自圈养行为实验的数据，这些数据显示了 Piper 成熟果实中的酰胺如何减少种子的保留时间并改变食物选择。通过新的分析，我们表明这些防御性次要化合物也延迟了水果去除的时间。接下来，使用行为注释的蝙蝠遥测数据集，我们量化了喂食后的运动（即种子传播距离）。使用广义加性混合模型，我们发现种子传播距离随肠道保留时间以及水果去除时间呈非线性变化。通过询问模型预测，