The study of flowering plant evolution through phylogeny has often included analyses of pollen. Mostly limited to traditional morphometric methods, pollen studies often bin traits and treat features like shape and size using discrete categories.
In this paper, authors present a novel approach to pollen evolution study based on quantitative size and shape variables. They used images of Myrtales pollen grains from two different angles to measure length and width of the grains, while analyzing outlines of the shape and converting these into elliptic transformations used for comparisons.
They analyzed pollen size and shape in a phylogenetic context and found significant differences among Myrtales families when comparing both shape and size. To test for linkages betwen pollen features and climate, the authors used GBIF-mediated occurrences and found that pollen shape was correlated with the mean latitude of a species’ distribution.
The novel morphometric approaches presented in the study prove useful for taxonomic identification and phylogenetic placement of as yet unknown pollen fossils.