Pollen evolution in the Stryphnodendron clade (Leguminosae, Mimoseae)
Author:
Barduzzi Rafael Fernandes1ORCID, Barros-Souza Yago1, Goicochea Stefany Liau-Kang2, Borges Leonardo Maurici1
Affiliation:
1. UFSCar: Universidade Federal de Sao Carlos 2. Embrapa Recursos Geneticos e Biotecnologia: Empresa Brasileira de Pesquisa Agropecuaria Recursos Geneticos e Biotecnologia
Abstract
Abstract
Pollen morphology is a valuable tool for understanding plant evolution and taxonomy. In the legume family (Leguminosae), tribe Mimoseae exhibits diverse pollen traits, but their taxonomic implications are not consistently considered. The pollen evolution in the Leguminosae family is marked by conservatism, but also suffers influence of evolutionary pressures, which increases diversity. Here we investigated the pollen evolution of the Stryphnodendron clade (Leguminosae, Mimoseae) and how it relates to changes in generic circumscriptions within the clade. We analyzed six morphological traits (three categorical and three continuous) sourced from herbarium specimens and the literature for 44 taxa. Categorical traits comprised number of units in the dispersal unit, outline, and grain pollen ornamentation, while continuous traits encompassed exine thickness, as well as longer and shorter dispersal unit diameters. All characters were mapped over a comprehensive phylogenetic hypothesis for the clade using stochastic character mapping and maximum likelihood estimations. Our results reveal that some traits, such as grain number and outline, are generally more conserved than others, such as pollen ornamentation and continuous traits, which are more labile. Pollen ornamentation is different between two distinct lineages within the Stryphnodendron clade, each including multiple genera. Continuous traits, on the other hand, show a contrasting pattern for the recently described genus Gwilymia. In conclusion, although pollen traits are in general conserved within the Stryphnodendron clade, they support recognition of distinct lineages both above and at the genus level. These findings highlight the importance of incorporating pollen morphology in future assessments of generic delimitation within the legume family.
Publisher
Research Square Platform LLC
Reference52 articles.
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