Herrera Javier
Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain.
Ann Bot. 2009 May;103(7):1119-27. doi: 10.1093/aob/mcp046. Epub 2009 Mar 2.
While pollinators may in general select for large, morphologically uniform floral phenotypes, drought stress has been proposed as a destabilizing force that may favour small flowers and/or promote floral variation within species.
The general validity of this concept was checked by surveying a taxonomically diverse array of 38 insect-pollinated Mediterranean species. The interplay between fresh biomass investment, linear size and percentage corolla allocation was studied. Allometric relationships between traits were investigated by reduced major-axis regression, and qualitative correlates of floral variation explored using general linear-model MANOVA.
Across species, flowers were perfectly isometrical with regard to corolla allocation (i.e. larger flowers were just scaled-up versions of smaller ones and vice versa). In contrast, linear size and biomass varied allometrically (i.e. there were shape variations, in addition to variations in size). Most floral variables correlated positively and significantly across species, except corolla allocation, which was largely determined by family membership and floral symmetry. On average, species with bilateral flowers allocated more to the corolla than those with radial flowers. Plant life-form was immaterial to all of the studied traits. Flower linear size variation was in general low among conspecifics (coefficients of variation around 10 %), whereas biomass was in general less uniform (e.g. 200-400 mg in Cistus salvifolius). Significant among-population differences were detected for all major quantitative floral traits.
Flower miniaturization can allow an improved use of reproductive resources under prevailingly stressful conditions. The hypothesis that flower size reflects a compromise between pollinator attraction, water requirements and allometric constraints among floral parts is discussed.
虽然传粉者通常会选择大型、形态均匀的花表型，但干旱胁迫被认为是一种破坏稳定的力量，可能有利于小花和/或促进物种内的花变异。
通过调查38种昆虫传粉的地中海物种的分类学多样性阵列，检验了这一概念的普遍有效性。研究了新鲜生物量投资、线性大小和花冠分配百分比之间的相互作用。通过主轴回归研究性状之间的异速生长关系，并使用一般线性模型多变量方差分析探索花变异的定性相关性。
在不同物种中，花在花冠分配方面完全呈等比缩放（即较大的花只是较小花的放大版本，反之亦然）。相比之下，线性大小和生物量呈异速生长变化（即除了大小变化外，还有形状变化）。除花冠分配外，大多数花变量在不同物种间呈显著正相关，花冠分配在很大程度上由所属科和花的对称性决定。平均而言，两侧对称花的物种比辐射对称花的物种在花冠上的分配更多。植物生活型与所有研究性状无关。同种植物间花的线性大小变化通常较低（变异系数约为10%），而生物量通常不太均匀（例如， salvifolius岩蔷薇中为200 - 400毫克）。在所有主要的花数量性状上都检测到了显著的种群间差异。
在普遍存在压力的条件下，花的小型化可以更好地利用生殖资源。讨论了花大小反映传粉者吸引力、水分需求和花各部分之间异速生长限制之间折衷的假说。
