SSK-Project 2009 Aylostera-Mediolobivia

Previous Results

The results of our molecular biological studies (Ritz et al. 2007) show that the genus Rebutia is not monophyletic. Rebutia sensu lato is not a natural kinship. Our phylogenetic tree rather reflects the subdivision of the Rebutia in three separate genera Aylostera, Mediolobivia, and Rebutia as adopted by Backeberg (1977) in the sense of Krainz (1967). In our study Rebutia (sensu Backeberg) is represented by two taxa with hairless pericarpels: the type species R. minuscula K. Schum. and R. padcayensis (Rausch) that are located along with Sulcorebutia und Weingartia on branch E in our tree. The species with hairy or bristly pericarpels (Aylostera and Mediolobivia sensu Backeberg) form branch D. Within this branch three subgroups can be identified:

  1. R. pseudodeminuta Backeb., R.fiebrigii (Gürke) Britton & Rose and R. deminuta (F.A.C. Weber) Britton & Rose (Aylostera in Backeberg's classification)
  2. R. pygmaea (R.E.Fr.) Britton & Rose R. steinmannii (Solms) Britton & Rose
  3. R. einsteinii Fric.

Bayesian Phylogeny

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Phylogeny based on Maximum Parsimony

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Distribution Area

Verbreitungsgebiete Aylostera-Mediolobivia-Rebutia s.s.
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Concept Aylostera-Mediolobivia 2009

The objective is to investigate the infra-generic relationships in branch D (highlighted in yellow in our tree) with the groupings Aylostera and Mediolobivia (sensu Backeberg) with molecular biological methods.

In continuation of our previous work we aim to answer following questions:

  1. Is it possible to separate the genera from Aylostera and Mediolobivia each other?
  2. Are morphological characters and genetic data compatible?
  3. Do we find a geographic pattern within the data that may allow us to reconstruct the evolution and the dispersal history of the complex?

Our hitherto experience has shown that sequence analysis alone resolves the affinities only insufficinetly. On the other hand the AFLP® method reaches its limits when individuals under investigation are related relatively distant. Therefore, it is necessary to create a phylogeny with described species as a framework and examine the results with the AFLP® method. This approach requires a sampling that keeps the geographical gaps between the populations as small as possible while the entire known range needs to be covered as regularly as possible.
The work has been completed in 2015. The results were reported in August 2016 in Plant Systematics and Evolution, Volume 302, Issue 7, pp 763-780 under the title “Molecular phylogenetic relationships of the Andean genus Aylostera Speg. (Cactaceae, Trichocereeae), a new classification and a morphological identification key”.

Abstract: The Andes represent a hotspot of diversity within Cactaceae. Owing to its small globular growth and its diverse flower colours the Andean genus Aylostera Speg. has drawn the attention of many cactus enthusiasts. Based on molecular data, the genus was recently split from Rebutia s. l. In contrast to the large number of taxa described within Aylostera, a comprehensive phylogenetic reconstruction is still warranted. The aim of our study was to reconstruct a phylogeny of Aylostera and to review its taxonomy based on morphological characters. We sequenced the chloroplast DNA markers atpB-rbcL and trnS-trnG intergenic spacers and scored amplified fragment lengths polymorphisms (AFLPs). We reconstructed phylogenetic trees and analysed results of AFLP neighbour-nets, Bayesian clustering and Principal Coordinate Analysis based on this genetic data. Our data demonstrated that Aylostera is monophyletic and is best recognized as a separate genus because it is only distantly related to the clade containing the type species of Rebutia. Within Aylostera we detected three clades—the Digitorebutia clade, the Aylostera sensu stricto clade and the A. einsteinii clade—which are characterized by unique combinations of morphological character states. The species composition of these clades was largely congruent between the molecular markers but AFLP data indicated some admixture. Based on genetic and morphological characters, we propose a new classification of Aylostera and present a key to species recognizing nine species.

Contact:

References:
BACKEBERG, C. 1977. Das Kakteenlexikon. Gustav Fischer Verlag, Jena.
KRAINZ, H. 1967. Die Kakteen: eine Gesamtdarstellung der eingeführten Arten nebst Anzucht- und Pflege-Anweisungen. Franckh'sche Verlagshandlung, Stuttgart.
RITZ, C. M., L. MARTINS, R. MECKLENBURG, V. GOREMYKIN und F. H. HELLWIG. 2007. The molecular phylogeny of Rebutia (Cactaceae) and its allies demonstrates the influence of paleogeography on the evolution of South American mountain cacti. American Journal of Botany 94: 1321-1332.

This project is conducted in collaboration with the Department of Systematic Botany, University of Giessen, Germany. It is financed by the members of the SSK.

Study Community of South American Cacti