Inter- and intraspecific variation in grass phytolith shape and size: a geometric morphometrics perspective

Area of Science:

• Paleobotany
• Morphometrics
• Plant Science

Background:

• Understanding phytolith variation is crucial for identifying fossil grasses and reconstructing past environments.
• Limited studies have explored inter- and intraspecific contributions to phytolith shape and size variation.

Purpose of the Study:

• To quantify sources of phytolith shape and size variation using geometric morphometrics.
• To assess the taxonomic significance of phytolith shape in closely related grass species.

Main Methods:

• Landmark-based geometric morphometrics applied to phytoliths of two grass species (Brachypodium pinnatum and B. sylvaticum).
• Analysis of 1200 phytoliths per species from multiple populations and plants.
• Multivariate statistical analyses including Procrustes ANOVA, regression, PCA, and LDA.

Main Results:

• Interspecific variation in phytolith shape was substantially greater than intraspecific variation.
• Phytolith shapes allowed for 83% accurate classification into their respective species.
• Intraspecific variation among populations was low, suggesting limited environmental influence on shape.

Conclusions:

• Phytolith shape strongly correlates with taxonomic identity in closely related grass species.
• The applied geometric morphometric approach effectively quantifies and separates variation sources.
• Grass phytoliths are valuable for reconstructing past vegetation dynamics.