Synzoochory selects for interannual variation in reproduction in perennial plants

<strong>Aim:</strong> Reproduction in perennial plants varies from relatively constant among years to production of massive and synchronous seed crops at irregular intervals, a reproductive strategy called mast seeding. The sources of that interspecific differences in the extent of interannual variation in seed production are largely unknown. <strong>Location:</strong> Interannual variation in seed production of 340 plant species located world-wide. <strong>Methods:</strong> We conducted a global meta-analysis of 340 animal-dispersed species to quantify how the interannual variability of seed crops of plants can be explained by seed mass, dispersal mode, phylogeny and climate. <strong>Results:</strong> Phylogenetic analysis indicated that interannual variation in seed production and seed mass tend to be similar in related species owing to their shared evolutionary. Interannual variation in seed production was 1.22 times higher in synzoochorous compared to endozoochorous species. Moreover, production of small seeds was associated with higher interannual variation in seed production although synzoochorous species produce larger seeds than endozoochorous species. Precipitation rather than temperature showed significant positive effect on interannual variation in seed production. Seed mass and dispersal mode contribute more to interannual variation in seed production than phylogeny, climate and fruit type. <strong>Main conclusion:</strong> Our study lends support to a long-standing notion that interspecific variation in masting intensity is largely shaped by the interactions of plants with animals. Masting is avoided when interannual variation in seed production can harm mutualists and promoted when satiation can decrease predation and increase seed dispersal.

**研究目的：** 多年生植物的繁殖模式在年度间存在广泛差异，从每年相对稳定的结实模式，到间隔不规则的大规模同步结种，这种生殖策略被称为**集中结实（mast seeding）**。目前学界对造成不同物种间种子生产年际变化程度差异的核心原因仍知之甚少。
**研究区域：** 本次研究覆盖全球范围内340种植物的种子生产年际变异性数据。
**研究方法：** 我们针对340种动物传播植物开展了一项全球荟萃分析，旨在量化植物种子生产的年际变异性可通过种子质量、传播方式、系统发育以及气候得到何种程度的解释。
**研究结果：** 系统发育分析显示，由于近缘物种共享演化背景，其种子生产的年际变异性与种子质量往往表现出相似性。体外动物传播（synzoochorous）物种的种子生产年际变异性较体内动物传播（endozoochorous）物种高出1.22倍。此外，尽管体外动物传播物种的种子质量高于体内动物传播物种，但小型种子的生产往往与更高的种子生产年际变异性相关联。降水而非温度对种子生产的年际变异性具有显著的正向影响。相较于系统发育、气候以及果实类型，种子质量与传播方式对种子生产年际变异性的解释贡献度更高。
**主要结论：** 本研究为学界长期以来的观点提供了实证支撑：即不同物种间集中结实强度的差异，主要由植物与动物的相互作用所塑造。当种子生产的年际变异性会损害互利共生伙伴时，植物会规避集中结实策略；而当通过种子饱和捕食者能够降低捕食压力并提升种子传播效率时，植物则会倾向于演化出集中结实的策略。