Inter- and intraspecific variation in grass phytolith shape and size: a geometric morphometrics perspective |
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Authors: | Kristý na Hoš ková ,Adé la Pokorná ,Jiř í Neustupa,Petr Pokorný |
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Affiliation: | 1. Department of Botany, Faculty of Sciences, Charles University in Prague, Benátská, Praha, Czech Republic;2. Institute of Archaeology, Czech Academy of Sciences, Letenská, Praha, Czech Republic;3. Center for Theoretical Study, Joint Research Institute of Charles University and Czech Academy of Sciences, Husova, Praha, Czech Republic |
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Abstract: | Background and AimsThe 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.MethodsWe 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.Key ResultsInterspecific 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.ConclusionsOur 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. |
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Keywords: | Phytolith analysis intraspecific variation landmark-based geometric morphometrics generalized Procrustes superimposition paleoecology Brachypodium pinnatum Brachypodium sylvaticum |
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