Data from: Temporal dynamics of seed excretion by wild ungulates: implications for plant dispersal

Dispersal is a key process in metapopulation dynamics as it conditions species' spatial responses to gradients of abiotic and biotic conditions and triggers individual and gene flows. In the numerous plants that are dispersed through seed consumption by herbivores (endozoochory), the distance and effectiveness of dispersal is determined by the combined effects of seed retention time in the vector's digestive system, the spatial extent of its movements, and the ability of the seeds to germinate once released. Estimating these three parameters from experimental data is therefore crucial to calibrate mechanistic metacommunity models of plant–herbivore interactions. In this study, we jointly estimated the retention time and germination probability of six herbaceous plants transported by roe deer (Capreolus capreolus), red deer (Cervus elaphus), and wild boar (Sus scrofa) through feeding experiments and a Bayesian dynamic model. Retention time was longer in the nonruminant wild boar (>36 h) than in the two ruminant species (roe deer: 18–36 h, red deer: 3–36 h). In the two ruminants, but not in wild boar, small and round seeds were excreted faster than large ones. Low germination probabilities of the excreted seeds reflected the high cost imposed by endozoochory on plant survival. Trait-mediated variations in retention time and germination probability among animal and plant species may impact plant dispersal distances and interact with biotic and abiotic conditions at the release site to shape the spatial patterns of dispersed plant species.

扩散（Dispersal）是集合种群动态（metapopulation dynamics）中的关键过程，它调控物种对非生物与生物条件梯度的空间响应，并驱动个体流动与基因流。在众多通过草食动物取食种子实现体内传播（endozoochory）的植物类群中，扩散距离与扩散效能由三项因素共同作用决定：种子在传播媒介消化系统内的滞留时间、媒介活动的空间范围，以及种子被排出后的萌发能力。因此，基于实验数据估算这三项参数，对于校准植物-草食动物互作的机制性元群落模型至关重要。本研究通过饲喂实验与贝叶斯动态模型（Bayesian dynamic model），联合估算了由狍（Capreolus capreolus）、马鹿（Cervus elaphus）及野猪（Sus scrofa）携带的6种草本植物的种子滞留时间与萌发概率。分析结果显示，非反刍动物野猪的种子滞留时长（>36小时）长于两种反刍动物（狍：18~36小时；马鹿：3~36小时）。在两种反刍动物中（而非野猪），小型圆形种子的排出速率快于大型种子。被排出种子的低萌发率，反映了体内传播对植物存活所施加的高昂代价。不同动物与植物物种间，由性状介导的种子滞留时间与萌发概率差异，可能会影响植物扩散距离，并与释放位点的生物及非生物条件产生互作，进而塑造传播植物物种的空间分布格局。