Articles

author1Julien Massoni
Laboratoire Ecologie, Systématique, Evolution
Université Paris-Sud
CNRS UMR 8079
91405 Orsay
France
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Julien Massoni is finishing his PhD at Université Paris-Sud. He is studying the evolutionary history of Magnoliidae, a large clade of angiosperms. During the last three years, he gained skills in molecular phylogeny reconstruction, molecular dating, diversification dynamic studies, reconstruction of ancestral traits, and placement of fossil species in extant phylogenies.

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author2James Doyle
Department of Evolution and Ecology
University of California
Davis, California 95616
USA
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James A. Doyle is a paleobotanist and plant evolutionist interested in the origin and early evolution of angiosperms. He received his PhD from Harvard University in 1971 and has held faculty positions at the University of Michigan and the University of California, Davis. His research has ranged from studies of Early Cretaceous fossil pollen and leaves to phylogenetic analyses of living and fossil seed plants and “basal” angiosperms. Much of his current work focuses on integration of early fossil angiosperms into molecular phylogenies of living plants and their geological and evolutionary implications.

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author3Hervé Sauquet
Laboratoire Ecologie, Systématique, Evolution
Université Paris-Sud
CNRS UMR 8079
91405 Orsay
France
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Hervé Sauquet is an evolutionary botanist with a primary interest in the use of phylogenetic trees to address questions of morphological evolution and diversification of flowering plants (angiosperms). He obtained his PhD in 2003 at Université Pierre et Marie Curie, where he studied the phylogeny and morphological evolution of Magnoliales. Since then, he has gained interest and experience with molecular dating methods and in particular their calibration with the fossil record. His research at Université Paris-Sud now focuses on floral evolution and diversification of angiosperms in general, and Magnoliidae in particular.

 

FIGURE 1. Simplified phylogenetic tree of Magnoliidae, after Massoni et al. (2014). Hydnoraceae (Piperales) are excluded, because the family was not included in original publications positioning the 10 fossils considered here. Colored boxes summarize the positions of fossils reviewed in the present paper. Their specific positions are figured by small branches with the number of the corresponding fossil at the tip. These correspond to the most parsimonious position(s) found for each fossil in previous phylogenetic analyses (see text for details). The minimum ages provided by the fossils are presented at the nodes they calibrate. The dashed branch refers to the phylogenetic uncertainty about relationships among Hernandiaceae, Lauraceae, and Monimiaceae (the position of Fossil 7 is on a branch not represented here, corresponding to a different set of relationships among these three families). Fossils are numbered following their order in the text. Abbreviations: Ma, million anni.

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TABLE 1. Summary of the calibration points provided in the present paper. Abbreviations: Ma, million anni.

Fossil Taxon

Node

Minimum Age

Endressinia brasiliana

Crown-group Magnoliineae (Doyle and Endress, 2010; Mohr et al., 2013)

112.6 Ma

Schenkeriphyllum glanduliferum

Crown-group Magnoliineae (Mohr et al., 2013)

112.6 Ma

Archaeanthus linnenbergeri

Stem Magnoliaceae (Doyle and Endress, 2010)

96.5 Ma

Virginianthus calycanthoides

Crown-group Laurales (Doyle et al., 2008)

107.7 Ma

Lovellea wintonensis

Crown-group Laurales (Dettmann et al., 2009)

100.1 Ma

Jerseyanthus calycanthoides

Crown-group Calycanthoideae (Crepet et al., 2005)

85.8 Ma

Cohongarootonia hispida

Crown-group core Laurales (von Balthazar et al., 2011)

107.7 Ma

Mauldinia mirabilis

Crown-group core Laurales (Doyle and Endress, 2010)

95.5 Ma

Walkeripollis gabonensis

Crown-group Canellales (Doyle and Endress, 2010)

125.9 Ma

Saururus tuckerae

Stem node of extant Saururus (Smith and Stockey, 2007)

44.3 Ma

 
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Fossil calibration of Magnoliidae, an ancient lineage of angiosperms

Julien Massoni, James Doyle, and Hervé Sauquet

Plain Language Abstract

In order to add a time dimension to evolutionary trees (phylogenies) of organisms based on molecular (DNA) data, current methods require reference points anchored in geological time. These reference points, referred to as calibrations, usually take the form of minimum and maximum ages for one or more groups in the phylogeny, based on their fossil record. For instance, if a fossil species is shown to have evolved within a particular living branch of the evolutionary tree, we can say that the most recent common ancestor of this branch is older than the fossil. Because of their great influence on the results, the age and phylogenetic position of the selected extinct taxa must be carefully estimated with geological and phylogenetic methods. The present study provides a list of 10 fossils suitable for defining minimum ages for several major groups of Magnoliidae, a large and ancient group of flowering plants that includes magnolias, laurels, black pepper, and their relatives. First, we thoroughly reviewed the geological literature in order to accurately define their ages, nine of which are from the middle part of the Cretaceous Period, ranging from ca. 126 to 86 million years ago. Second, we took into account all previously published phylogenetic analyses of these 10 fossils to securely identify the branch points in the tree that they constrain. This new list will be essential for conducting molecular dating analyses at all scales in the flowering plant tree of life as well as for dating the evolutionary history of Magnoliidae.

Glossary
Crown node: the most recent common ancestor of a living group of species.
Stem node: the common ancestor of a group of living species and its closest living relatives (sister group).

Resumen en Español

Calibración fósil de Magnoliidae, un antiguo linaje de angiospermas

Con el fin de investigar la diversificación de las angiospermas, es necesario un marco temporal preciso. Los métodos de datación molecular completamente calibrados con el registro fósil pueden proporcionar estimaciones de esta escala de tiempo evolutivo. Debido a su posición en el árbol filogenético de las angiospermas, los representantes de Magnoliidae (10.000 especies) son de importancia primordial para la investigación de la historia evolutiva de las plantas con flores. El rico registro fósil del grupo, iniciado en el Cretácico, tiene una distribución global. Entre el centenar de especies extintas de Magnoliidae descrito, varias de ellas han sido incluidas en los análisis filogenéticos junto a especies existentes, proporcionando puntos de calibración fidedignos para los estudios de datación molecular. Hasta ahora, son pocos los fósiles que se han utilizado como puntos de calibración de Magnoliidae, siendo además que la posición filogenética y la edad absoluta de los mismos no se han justificado detalladamente. En este artículo examinamos la posición filogenética y las edades de 10 fósiles de Magnoliidae, los cuales han sido seleccionados ya que se habían incluido previamente en análisis filogenéticos de taxones fósiles y actuales. Este estudio nos permite proponer un esquema de calibración actualizado para la datación de la historia evolutiva de Magnoliidae.

Palabras clave : Calibración fósil; Canellales; Laurales; Magnoliales; Magnoliidae; Piperales

Traducción: Enrique Peñalver

Résumé en Français

Etalonnage fossile de la famille Magnoliidae, une ancienne lignée d'angiospermes

Afin d'étudier la diversification des angiospermes, un cadre temporel précis est nécessaire. Des méthodes de datations moléculaires soigneusement calibrées avec des fossiles peuvent fournir des estimations de cette échelle de temps évolutive. En raison de leur position dans l'arbre phylogénétique des angiospermes, les Magnoliidae (10 000 espèces) sont de première importance pour l'enquête de l'histoire évolutive des plantes à fleurs. Le riche registre fossile de ce groupe, commençant au Crétacé, a une distribution mondiale. Parmi les centaines d'espèces éteintes de Magnoliidae décrites, plusieurs ont été inclus dans des analyses phylogénétiques aux côtés d'espèces existantes, fournissant des points d'étalonnage fiables pour les études de datations moléculaires. Jusqu'à présent, peu de fossiles ont été utilisés comme points d'étalonnage chez les Magnoliidae, et les justifications détaillées de leur position phylogénétique et de leur âge absolu ont été insuffisantes. Ici, nous passons en revue la position et l'âge de 10 fossiles de Magnoliidae, choisis en raison de leur inclusion précédente dans des analyses phylogénétiques de taxons actuels et fossiles. Cette étude nous permet de proposer une mise à jour du système d'étalonnage pour la datation de l'histoire évolutive des Magnoliidae.

Mots-clés: étalonnage de fossiles; Canellales; Laurales; Magnoliales; Magnoliidae; Piperales

Translator: Kenny J. Travouillon

Deutsche Zusammenfassung

Fossil-Kalibrierung der Magnoliidae, eine altertümliche Linie der Angiospermen

Für die Erforschung der Angiospermen-Diversifikation ist ein genauer zeitlicher Rahmen nötig. Molekulare Datierungsmethoden, die sorgfältig mit dem Fossilbericht kalibriert wurden, können Schätzungen für diese evolutionäre Zeitskala liefern. Wegen ihrer Position im phylogenetischen Baum der Angiospermen sind die Magnoliidae (10 000 Arten) für die Erforschung der Entwicklungsgeschichte der Blütenpflanzen von elementarer Bedeutung. Der reichhaltige Fossilbericht dieser Gruppe, der in der Kreidezeit begann, ist global verbreitet. Unter den ausgestorbenen Arten der beschriebenen Magnoliidae wurden einige in phylogenetische Analysen an der Seite von heutigen Arten miteinbezogen und haben zuverlässige Kalibrierungspunkte für molekulare Datierungsstudien geliefert. Bis jetzt wurden nur wenige Fossilien als Kalibrierungspunkte für die Magnoliidae genutzt und detaillierte Angaben zu ihrer phylogenetischen Position und des absoluten Alters fehlten. Hier prüfen wir die Position und das Alter von 10 Magnoliidae-Fossilien, die aufgrund ihrer bisherigen Einbeziehung in phylogenetische Analysen über heutige und fossile Taxa ausgewählt wurden. Diese Studie erlaubt uns die Präsentation eines aktuellen Kalibrierungsschemas zur Datierung der Entwicklungsgeschichte der Magnoliidae.

Schlüsselwörter: Fossil-Kalibrierung; Canellales; Laurales; Magnoliales; Magnoliidae; Piperales

Translator: Eva Gebauer

Arabic

435 arab

Translator: Ashraf M.T. Elewa