Data for Rodrigues et al. 2025. Flower size in the Pantanal

Flower size plays a crucial role in the reproduction of animal-pollinated plants. Larger flowers usually increase pollinator visitation and reproductive success, but they are also associated with higher water investment for production and maintenance. Thus, water availability is a relevant factor in determining flower size, which may be consequently reduced in hot and dry environments. However, the phylogenetic relationships across plants may limit the variation of flower size, a strongly conserved trait among closely related species. We tested this hypothesis across 97 animal-pollinated species in the Pantanal, the world's largest tropical wetland. To determine how phylogeny and water availability affect community-level flower size, we quantified the variation of this trait between seasons (dry and rainy), substrates (terrestrial and aquatic) and species (phylogenetic signal). We observed a high variability in flower size, which showed a significant phylogenetic signal. Conversely, we did not detect a significant influence of season and substrate on flower size, although we observed a trend towards larger flowers in aquatic species, especially during the rains. Our results demonstrate that phylogeny mostly determines flower size variation in the Pantanal. Our findings also suggest that water availability may still exert evolutionary pressures on flower size, even in a context of phylogenetic conservatism. This study highlights the need to investigate the multiple interacting factors shaping flower size and contributes to a deeper understanding of its variation in response to environmental factors and phylogeny.

花的大小在动物传粉植物的繁殖中起着至关重要的作用。较大的花通常会提高传粉者的访花率和繁殖成功率，但它们的生成和维持也需要更多的水分投入。因此，水分可利用性是决定花大小的一个相关因素，在炎热干燥的环境中，花的大小可能会随之减小。然而，植物间的系统发育关系（phylogenetic relationships）可能会限制花大小的变异——这是近缘物种间高度保守的性状。我们在世界最大的热带湿地——潘塔纳尔湿地中，对97种动物传粉植物进行了这一假设的验证。为了确定系统发育（phylogeny）和水分可利用性如何影响群落水平的花大小，我们量化了该性状在季节（干旱季和雨季）、生境类型（陆地和水生）以及物种间（系统发育信号，phylogenetic signal）的变异。我们观察到花大小具有高度变异性，且表现出显著的系统发育信号。相反，我们未检测到季节和生境类型对花大小的显著影响，尽管观察到水生物种的花有变大的趋势，尤其是在雨季期间。我们的结果表明，在潘塔纳尔湿地中，系统发育是决定花大小变异的主要因素。我们的研究结果还表明，即使在系统发育保守性（phylogenetic conservatism）的背景下，水分可利用性仍可能对花大小施加进化压力。本研究强调了探究影响花大小的多种相互作用因素的必要性，并有助于深入理解花大小对环境因素和系统发育的响应变异。