Data from: Angiosperm fleshy fruits and seed dispersers: a comparative analysis of adaptation and constraints in plant-animal interactions

Variation in phenotypic traits of angiosperm fleshy fruits has been explained as the result of adaptations to their mutualistic seed dispersers. By analyzing the information available on fleshy fruit characteristics of 910 angiosperm species, I assess the hypothesis of evolutionary association between fruit phenotypic traits and type of seed disperser (birds, mammals, and mixed dispersers) and address explicitly and quantitatively alternative null hypotheses about phylogenetic effects. Phylogenetic affinity among plant taxa is accounted for by comparative methods including nested ANOVA, phylogenetic autocorrelation, and independent contrasts. Averaging over the 16 fruit traits examined, phylogenetic effects down to genus level explain 61% of total variance. Phylogenetic autocorrelations are strong among close relatives, reaching significance for 11 of the 16 fruit traits examined. When assessed by independent contrast methods, correlated evolution between type of disperser and fruit traits is confined to fruit diameter. Differences among dispersal syndromes in other traits vanish after accounting for phylogenetic effects. These analyses reveal that seed dispersal syndromes are not entirely interpretable as current adaptations to seed dispersers. Their status as exaptations can be assessed by combining experimental studies of natural selection on fruit size and rigorous comparative and cladistic tests of adaptational hypotheses.

被子植物肉质果实的表型性状变异，历来被归因于对其互利共生种子传播者（mutualistic seed dispersers）的适应。本研究通过分析910种被子植物的肉质果实特征数据，检验了‘果实表型性状与种子传播者类型（鸟类、哺乳类及混合传播者）间存在进化关联’这一假说，并明确且定量地探讨了有关系统发育效应的备选零假说。研究采用嵌套方差分析（nested ANOVA）、系统发育自相关分析及独立对比法（independent contrasts）等比较分析方法，纳入植物类群间的系统发育亲缘关系。对所考察的16个果实性状取平均后发现，至属级阶元的系统发育效应可解释总变异的61%。近缘类群间的系统发育自相关强度较高，在所考察的16个果实性状中，有11个性状的自相关达到显著水平。通过独立对比法分析可知，传播者类型与果实性状间的协同进化仅局限于果实直径这一性状。在考虑系统发育效应后，其他果实性状在不同种子传播综合征（seed dispersal syndromes）间的差异便不复存在。本研究揭示，种子传播综合征并非完全可被解释为当前对种子传播者的适应。若要评估其作为外适应（exaptations）的属性，需结合果实大小相关自然选择的实验研究，以及对适应假说的严谨比较分析和支序分类检验。