Genetic and environmental disturbances are expected to increase developmental instability, which may result in higher fluctuating asymmetry (FA), i.e. small random deviations from symmetry. Plant leaves often do not show this pattern, possibly due to high phenotypic plasticity of leaf shape and low adaptive significance of leaf symmetry. In contrast, symmetry in many animal traits but also in flower shape is considered to be under selection, and FA in such traits may better reflect developmental instability. Using geometric morphometrics, I analysed the symmetry of flowers of inbred and outbred Mimulus guttatus (Phrymaceae) plants grown under five stress treatments with and without grass competition. Flower FA was not increased by abiotic stress, but by inbreeding and competition. As inbreeding and competition affected different principal components of flower FA, different mechanisms may be involved in their effects on FA. FA decreased with individual biomass particularly in selfed offspring, which suggests that inbreeding increased FA particularly when growth was limited by environmental or genetic constraints. Increased flower FA of inbred offspring may explain increased flower handling time and reduced pollinator preference for inbred plants in other M. guttatus studies, and could thus have important consequences for plant demography and plant–pollinator interactions.

中文翻译：

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近亲繁殖和竞争，而非非生物胁迫，增加了牙龈花的波动不对称性

预期遗传和环境干扰会增加发育的不稳定性，这可能导致更高的波动不对称性（FA），即与对称性之间的随机偏差较小。植物叶片通常不显示这种模式，可能是由于叶片形状的高表型可塑性和叶片对称性的适应性低。相反，许多动物性状中的对称性以及花朵形状中的对称性都被认为处于选择之下，而这些性状中的FA可能更好地反映了发育的不稳定性。我使用几何形态计量学分析了近交和近交Mimulus guttatus花的对称性（草科）在有和没有草竞争的情况下经过五种胁迫处理后生长的植物。花FA不是由于非生物胁迫而增加，而是由于近亲繁殖和竞争而增加。由于近亲繁殖和竞争影响花FA的不同主要成分，因此它们对FA的作用可能涉及不同的机制。FA随着个体生物量而下降，特别是在自交后代中，这表明近交FA增加，尤其是当生长受到环境或遗传限制时。自交后代的增加花FA可以解释增加花处理时间和其他授粉减少偏爱近交植物M.鱯研究，并因此可能具有植物人口和植物授粉的相互作用产生重要影响。