School of Biological Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, U.K.
Emerg Top Life Sci. 2022 Sep 9;6(3):285-294. doi: 10.1042/ETLS20210273.
Studies of shape asymmetry have become increasingly abundant as the methods of geometric morphometrics have gained widespread use. Most of these studies have focussed on fluctuating asymmetry and have largely obtained similar results as more traditional analyses of asymmetry in distance measurements, but several notable differences have also emerged. A key difference is that shape analyses provide information on the patterns, not just the amount of variation, and therefore tend to be more sensitive. Such analyses have shown that apparently symmetric structures in animals consistently show directional asymmetry for shape, but not for size. Furthermore, the long-standing prediction that phenotypic plasticity in response to environmental heterogeneity can contribute to fluctuating asymmetry has been confirmed for the first time for the shape of flower parts (but not for size). Finally, shape analyses in structures with complex symmetry, such as many flowers, can distinguish multiple types of directional asymmetry, generated by distinct direction-giving factors, which combine to the single component observable in bilaterally symmetric structures. While analyses of shape asymmetry are broadly compatible with traditional analyses of asymmetry, they incorporate more detailed morphological information, particularly for structures with complex symmetry, and therefore can reveal subtle biological effects that would otherwise not be apparent. This makes them a promising tool for a wide range of studies in the basic and applied life sciences.
随着几何形态测量学方法的广泛应用，对形状不对称性的研究变得越来越丰富。这些研究大多集中在波动不对称性上，并且与距离测量的不对称性的传统分析大致上得到了相似的结果，但也出现了一些值得注意的差异。一个关键的区别是，形状分析提供的是关于模式的信息，而不仅仅是变化的数量，因此往往更敏感。此类分析表明，动物中那些表面上对称的结构在形状上存在方向性不对称，而在大小上则没有。此外，长期以来一直预测，对环境异质性的表型可塑性可以导致波动不对称性，这一预测首次在花部形状上得到了证实（但在大小上没有）。最后，对于具有复杂对称性的结构（如许多花）的形状分析，可以区分由不同定向因素产生的多种类型的方向性不对称性，这些因素结合起来形成了在双侧对称结构中观察到的单一成分。虽然形状不对称性的分析与传统的不对称性分析广泛兼容，但它们包含了更详细的形态信息，特别是对于具有复杂对称性的结构，因此可以揭示出细微的生物学效应，否则这些效应是不明显的。这使得它们成为基础和应用生命科学中广泛研究的有前途的工具。
