Department of Botany, Faculty of Sciences, Charles University in Prague, Benátská, Praha, Czech Republic.
Institute of Archaeology, Czech Academy of Sciences, Letenská, Praha, Czech Republic.
Ann Bot. 2021 Jan 7;127(2):191-201. doi: 10.1093/aob/mcaa102.
The relative contributions of inter- and intraspecific variation to phytolith shape and size have only been investigated in a limited number of studies. However, a detailed understanding of phytolith variation patterns among populations or even within a single plant specimen is of key importance for the correct taxonomic identification of grass taxa in fossil samples and for the reconstruction of vegetation and environmental conditions in the past. In this study, we used geometric morphometric analysis for the quantification of different sources of phytolith shape and size variation.
We used landmark-based geometric morphometric methods for the analysis of phytolith shapes in two extant grass species (Brachypodium pinnatum and B. sylvaticum). For each species, 1200 phytoliths were analysed from 12 leaves originating from six plants growing in three populations. Phytolith shape and size data were subjected to multivariate Procrustes analysis of variance (ANOVA), multivariate regression, principal component analysis and linear discriminant analysis.
Interspecific variation largely outweighed intraspecific variation with respect to phytolith shape. Individual phytolith shapes were classified with 83 % accuracy into their respective species. Conversely, variation in phytolith shapes within species but among populations, possibly related to environmental heterogeneity, was comparatively low.
Our results imply that phytolith shape relatively closely corresponds to the taxonomic identity of closely related grass species. Moreover, our methodological approach, applied here in phytolith analysis for the first time, enabled the quantification and separation of variation that is not related to species discrimination. Our findings strengthen the role of grass phytoliths in the reconstruction of past vegetation dynamics.
种内和种间变异对植硅体形状和大小的相对贡献仅在有限数量的研究中进行了调查。然而，详细了解种群内甚至单个植物标本中的植硅体变异模式对于正确鉴定化石样本中草类分类群以及重建过去的植被和环境条件至关重要。在这项研究中，我们使用几何形态测量分析来量化植硅体形状和大小的不同来源。
我们使用基于地标点的几何形态测量方法分析了两种现存的草种（短柄草和林地短柄草）中的植硅体形状。对于每个物种，从生长在三个种群中的六株植物的 12 片叶子中分析了 1200 个植硅体。将植硅体形状和大小数据进行多元 Procrustes 方差分析（ANOVA）、多元回归、主成分分析和线性判别分析。
种间变异大大超过了种内变异对植硅体形状的影响。个体植硅体形状以 83%的准确率被归入各自的物种。相反，种内但种群间的植硅体形状变异可能与环境异质性有关，相对较低。
我们的结果表明，植硅体形状与密切相关的草类物种的分类身份相对接近。此外，我们在这里首次在植硅体分析中应用的方法学方法，能够量化和分离与物种鉴别无关的变异。我们的发现加强了草类植硅体在重建过去植被动态方面的作用。
