PEPEROMIA

September 2003 to present, collaborative research project

The pantropical genus Peperomia (Piperaceae), counting some 1 600 species, belongs to the top ten of the giant genera in Angiosperms. The genus is characterised by a deficit of morphological synapomorphies for infrageneric groups because of parallel evolution of macromorphological characters and extreme flower reduction. Therefore, a thorough phylogenetic analysis combining molecular and morphological data is essential for understanding character evolution.

We published the first phylogeny of the genus based on chloroplast trnK-matK sequences of about 50 species of all subgenera. This study indicated the paraphyly of most subgenera sensu Dahlstedt (1900) and suggested several new groupings. It was also shown here that several macromorphological characters (e.g. peltate leaves, paniculate inflorescences), on which the generally used infrageneric classification of Dahlstedt (1900) is based, have been subject to parallel evolution. Additionally, our nomenclatural study of all published infrageneric taxa indicated that several names are invalid and that some descriptions in the revision of Dahlstedt (1900) are quite aberrant from the original description.

These findings are also supported by additional molecular work based on nuclear ITS and 26S and mapping of morphological characters on a combined molecular tree, visualizing the contrast between previously used homoplasious characters and some newly observed characters, which can be used to delimit monophyletic groups. See Pandora’s Box for more information.

Another investigated set of characters are calcium oxalate crystals, which are known to occur in most plant groups. We studied and scored the shape, form and distribution of crystals in the different leaf parts in both Peperomia and its sister genus Piper and used character optimization strategies to evaluate the systematic importance. The leaf crystals are characterized by an increasing complexity and their presence and distribution has a certain systematic significance but similar to the morphology, only few characters were found to be of use as synapomorphies for infrageneric clades.

To obtain a representative, resolved and well-supported phylogenetic hypothesis we are currently working on a sampling of about 600 accessions (~250-300 species) for the trnK intron, the matK gene and the trnK-psbA spacer. The combination of nearly all the studies on Peperomia presented will constitute the basis for a new infrageneric classification reflecting phylogenetic relationships. As most large angiosperm genera with more than 500 species, Peperomia has no modern worldwide monograph and the traditional taxonomic subdivisions proved to be highly unnatural. The large size of these genera does not facilitate attempts to make infrageneric classifications and revisions and therefore, the evolutionary history of these genera is still poorly known.

With this frame available, we can divide the giant genus into smaller monophyletic clades which are more easily ‘digestible’ in a relatively short period of time. The first group we tackled was a relatively small group of 12 species sharing a particular morphological character, the so-called pseudo-epiphyllous inflorescences. More recently, we have described several new tuberous species of Peperomia subgenus Tildenia from the Andes of Bolivia and Peru, Mexico and Central America, primarily based on our own collections and field observations in this area. Consequently, we performed a phylogenetic and biogeographical study of this subgenus, leading to a better understanding of the evolution of this group of approximately 60 species.

Currently, we tackle the next monophyletic group of Peperomia, the succulent, so-called window-leaved Peperomia species. This clade is distributed in arid zones from southern Ecuador to southern Peru, showing the highest diversity in arid zones in northern Peru.

Finally, we are also involved in floristic studies in several countries in the Neotropics, where the highest diversity of the genus Peperomia can be encountered.
The Peperomia collection in the Ghent University Botanical Garden is of indispensable value for our research and now includes about 2000 specimens of approximately 700 species of all subgenera, and is still increasing. It is together with the collection of our German cooperation partners in the Botanical Garden of the Technical University Dresden (TU Dresden) the largest and most representative living ex situ collection of Peperomia in the world.
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Relevant publications:
Pino G, Cieza N, Wanke S, Samain MS. (2012) New succulent window-leaved Peperomias from Peru. Haseltonia 18: 3-26.
Horner HT, Wanke S, Samain MS. (2012) Evolution and systematic value of leaf crystal macropatterns in the genus Piper (Piperaceae): a comparison with the genus Peperomia. American Journal of Botany 99: 983-997.
Naumann J, Symmank L, Samain MS, Müller KF, Neinhuis C, dePamphilis CW, Wanke S. (2011) Chasing the hare – Evaluating the phylogenetic utility of a nuclear single copy gene region at and below species level within the species rich group Peperomia (Piperaceae). BMC Evolutionary Biology 11: 357.
Fonseca RM, Samain MS. (2011) Peperomia. In: García-Mendoza AJ, Meave JA (eds.), Diversidad florística de Oaxaca: de musgos a angiospermas (colecciones y lista de especies: 270-271.
Symmank L*, Samain MS*, Smith JF, Pino G, Goetghebeur P, Neinhuis C, Wanke S. (2011) From the Andean cradle in Peru to the Trans-Mexican Volcanic Belt: the extraordinary journey of the geophytic Peperomia subgenus Tildenia (Piperaceae). Journal of Biogeography 38 (12): 2337-2349. (*equal contribution)
Mathieu G, Symmank L, Callejas R, Wanke S, Neinhuis C, Goetghebeur P, Samain MS. (2011) New geophytic Peperomia (Piperaceae) species from Mexico, Belize and Costa Rica. Revista Mexicana de Biodiversidad 82: 357-382.
Samain MS, Mathieu G, Pino G, Symmank L, Cieza N, Neinhuis C, Goetghebeur, Wanke S. (2011) The geophytic Peperomia subgenus Tildenia (Piperaceae) in the Andes with the description of new species in a phylogenetic framework. Plant Ecology and Evolution 144 (2): 148-176.
Samain MS, Vanderschaeve L, Chaerle P, Goetghebeur P, Neinhuis C, Wanke S. (2009) Is morphology telling the truth about the evolution of the giant genus Peperomia (Piperaceae)? Plant Systematics and Evolution 280: 251-254. (erratum)
Samain MS, Vanderschaeve L, Chaerle P, Goetghebeur P, Neinhuis C, Wanke S. (2009) Is morphology telling the truth about the evolution of the giant genus Peperomia (Piperaceae)? Plant Systematics and Evolution 278: 1-21.
Horner H, Wanke S, Samain MS. (2009) Evolution and systematic value of leaf crystal macropatterns in the genus Peperomia (Piperaceae). International Journal of Plant Sciences 170: 343-354.
Mathieu G, Samain MS, Reynders M, Goetghebeur P. (2008) Taxonomy of the Peperomia species (Piperaceae) with pseudo-epiphyllous inflorescences, including four new species. Botanical Journal of the Linnean Society 157: 177-196.
Samain MS, Mathieu G, Vanderschaeve L, Wanke S, Neinhuis C, Goetghebeur P. (2007) Nomenclature and typification of subdivisional names of the genus Peperomia (Piperaceae). Taxon 56: 229-236.
Wanke S, Samain MS, Vanderschaeve L, Mathieu G, Goetghebeur P, Neinhuis C. (2006) Phylogeny of the genus Peperomia (Piperaceae) inferred from the trnK/matK region (cpDNA). Plant Biology 8: 93-102.

Principal investigator:
Dr. Marie-Stéphanie Samain

Associated researchers:
Dr. Guido Mathieu
Liesbeth Vanderschaeve

Laboratory technician:
Pieter Asselman

Supervisor:
Prof. Dr. Paul Goetghebeur

Collaboration:
Dr. Stefan Wanke - TU Dresden, Germany

Dr. Alexander Vrijdaghs - KULEUVEN, Belgium

Dr. Ricardo Callejas - Universidad de Antioquia, Medellín, Colombia
Dr. Guillermo Pino - Museo de Historia Natural, Lima, Peru
Nelson Cieza - Cajamarca, Peru

Dr. James F. Smith - Boise State University, USA
Dr. Harry T. Horner - Iowa State University, USA

Funding:
Research Foundation Flanders project grant (n° G.0172.07) & international mobility grants

German Science Foundation project grants (to German cooperation partner, DFG n° NE681/5-1, NE681/5-2)

German Academic Exchange Service

Universidad Peruana Cayetano Heredia project grant (to Peruvian cooperation partner, n° 084-PIN-2008)

A private sponsor

Friends of the Ghent University Botanical Garden (De Vrienden van de Plantentuin)

Ghent University
Department of Biology
Research Group Spermatophytes
Ghent University Botanical Garden