Data from: Seed dispersal anachronisms: rethinking the fruits extinct megafauna ate

BACKGROUND: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals >103 kg), yet these dispersers were extinct in South America 10–15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. METHODOLOGY/PRINCIPAL FINDINGS: We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4–10 cm in diameter with up to five large seeds, and fruits >10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size) with either a single or few (<3 seeds) extremely large seeds or many small seeds (usually >100 seeds). Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness. CONCLUSIONS/SIGNIFICANCE: Megafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal by relying on frugivores able to disperse enormous seed loads over long-distances. Present-day seed dispersal by scatter-hoarding rodents, introduced livestock, runoff, flooding, gravity, and human-mediated dispersal allowed survival of megafauna-dependent fruit species after extinction of the major seed dispersers. Megafauna extinction had several potential consequences, such as a scale shift reducing the seed dispersal distances, increasingly clumped spatial patterns, reduced geographic ranges and limited genetic variation and increased among-population structuring. These effects could be extended to other plant species dispersed by large vertebrates in present-day, defaunated communities.

BACKGROUND：新热带区肉质果植物中，部分类群的果实结构与由巨型动物群（megafauna，即体重>103千克的哺乳动物）传播的古热带区果实相似，但这类种子传播者已于10~15千年前（Kyr BP）在南美洲灭绝。时代错位的传播系统可通过与已灭绝动物的互作得到最佳解释，该系统会出现传播能力受损，进而改变种子传播动态。

METHODOLOGY/PRINCIPAL FINDINGS：本研究提出了巨型动物传播果实（megafaunal fruits）的可操作定义，并对符合该传播模式的103个新热带区果实物种开展比较分析。基于此前对象传果实的分析，我们定义了两类巨型动物传播果实：一类果实直径4~10厘米，含至多5枚大型种子；另一类果实直径>10厘米，含大量小型种子。巨型动物传播果实广泛分布于多个非近缘的科，如山榄科（Sapotaceae）、豆科（Fabaceae）、茄科（Solanaceae）、夹竹桃科（Apocynaceae）、锦葵科（Malvaceae）、油桃木科（Caryocaraceae）以及棕榈科（Arecaceae），这类果实兼具超量构建的结构特征（果实质量与体积均较大），要么仅含1枚或少数（<3枚）极大型种子，要么包含大量小型种子（通常>100枚）。在科内和属内层面，巨型动物传播果实物种与非该类群物种的对比分析显示，二者在果实直径与果实质量上存在显著差异，但单粒种子质量的差异相对较小；且存在显著趋势：巨型动物传播果实往往拥有更大的种子与更高的多籽性。

CONCLUSIONS/SIGNIFICANCE：巨型动物传播果实使得植物能够规避种子大小与传播能力之间的权衡，其依托的食果动物可将大量种子载荷长距离传播。在主要种子传播者灭绝后，现今依靠分散贮食啮齿类、引入家畜、地表径流、洪水、重力以及人类介导的传播方式，使得依赖巨型动物传播的果实物种得以存续。巨型动物灭绝存在多项潜在后果，例如：种子传播距离的尺度缩减、空间分布愈发聚集、地理范围缩小、遗传变异受限，以及种群间结构分化加剧。上述效应可推广至现今动物区系丧失的群落（defaunated communities）中其他由大型脊椎动物传播的植物类群。