Are morphological characteristics of Parrotia (Hamamelidaceae) pollen species diagnostic?

Benjamin Adroit, Fridgeir Grimsson, Jean-Pierre Suc, Gilles Escarguel, Reinhard Zetter, Johannes M. Bouchal, Séverine Fauquette, Xin Zhuang, Morteza Djamali

Parrotia persica is one of the most notable endemic relict tree species growing in the Hyrcanian forest at the southern Caspian Sea. The recent discovery of sibling species Parrotia subaequalis, occurring in the temperate forests of south-eastern China, offers the opportunity to compare their morphology and ecological preferences and to dig deeper into the paleophytogeographic history of the genus from a perspective. Since pollen morphology of these species would be essential to unravel the origin and evolution of these Arcto-Tertiary species, the present study aimed to investigate whether it is possible to segregate pollen from these two species. Therefore, a detailed combined light- and scanning electron microscopy-based pollen-analysis of each taxon was conducted, the pollen was described, measured, and compared using statistical approaches and principal component analyses to establish unbiased results. The correlation-based principal component analysis achieved for each species shows an overall good superposition of pollen grains measured in equatorial and polar views in the first principal plane, revealing that the P. persica pollen is morphometrically as homogeneous as that of P. subaequalis. Then, the significant difference, mainly driven by lumen density, has been highlighted between the two species. Ultimately, the cross-validation of the resulting two-species linear discriminants classifier shows that based upon this reference dataset, (sub)fossil pollen grain can now be confidently assigned to either of the two species with an 85.8% correct-assignment rate. This opens new doors in the affiliation of fossil Parrotia pollen and suggests that previous pollen records need to be revised.

Department für Botanik und Biodiversitätsforschung, Institut für Paläontologie
Externe Organisation(en)
Swedish Museum of Natural History, Sorbonne Université, Université Claude-Bernard-Lyon-I, Institut des Sciences de l'Evolution de Montpellier (ISEM), University of Helsinki, Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale (IMBE)
Review of Palaeobotany and Palynology
Anzahl der Seiten
ÖFOS 2012
105117 Paläobotanik, 106008 Botanik
ASJC Scopus Sachgebiete
Ecology, Evolution, Behavior and Systematics, Palaeontology
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