Data from: Water and fish select for fleshy fruits in tropical wetland forests

Adjacent floodplain and upland tropical forests experience the same temperature and precipitation regimes, but differ substantially in plant species composition and biotic interactions because of extensive flooding. We hypothesize that flooded forests filter fruiting traits linked to seed dispersal by water and fishes, such that selection by water and fish led to (1) trees that synchronize the timing of fruiting with annual floods, and (2) the evolution of fleshy tissues on fruits to improve buoyancy and increase fruit consumption rates by fish. To test this hypothesis, we compared plant communities in seasonally flooded forests and adjacent upland forest in terms of fruiting phenology, the frequency of trees bearing fleshy-fruit, and the role of fleshy tissues in buoyancy and seed viability. Beta-diversity in this system is high, with significant differences in species composition across habitats. As predicted, the production of ripe fleshy fruits was significantly greater in flooded than upland forests during the flood season. Furthermore, we found that trees with fleshy fruit were significantly more abundant in flooded forests even though species richness of fleshy-fruit bearing trees was proportionally similar in flooded and upland forests. Additionally, fleshy pulp increased buoyancy. Likewise, time afloat decreased for denser fruit and those with high seed to pulp ratios. In concert, these results suggest that fleshy fruits in Neotropical floodplain forests facilitated hydrochory and ichthyochory. Once established, water and fish became important agents of selection on fruiting traits.毗邻热带泛滥平原森林与周边旱地热带森林具有一致的温降水格局，但因广泛积水，二者在植物物种组成与生物相互作用方面存在显著差异。我们提出假说：泛滥森林会筛选出与水和鱼类介导的种子扩散相关的结实性状，由此水与鱼类施加的选择作用会催生两类特征：（1）树木将结实时间与年度洪水周期同步；（2）果实演化出肉质组织以提升浮力，并提高鱼类取食果实的速率。为验证该假说，我们对比了季节性泛滥森林与毗邻旱地森林的植物群落，分析指标涵盖结实物候、结肉质果树木的占比，以及肉质组织对浮力与种子活力的作用。本研究系统内的β多样性（Beta-diversity）较高，不同生境间的物种组成存在显著差异。正如预测所示，洪水季时泛滥森林中成熟肉质果的产量显著高于旱地森林。此外，尽管结肉质果树木的物种丰富度在泛滥森林与旱地森林中比例相近，但泛滥森林中结肉质果的树木个体丰度显著更高。进一步研究发现，肉质果肉可提升果实浮力；同样，果实密度越高、种子与果肉比越高，其漂浮时间越短。综上，这些结果表明新热带区泛滥平原森林中的肉质果实促进了水媒传播（hydrochory）与鱼媒传播（ichthyochory）。一旦群落构建完成，水与鱼类便成为了作用于结实性状的重要选择因子。