Systematics/Phytogeography / Taxonomie/ Section
Gurushidze, Maia , Blattner, Frank R. .
Molecular markers infer cryptic species within Allium subg. Melanocrommyum.
Allium subg. Melanocrommyum is a taxonomically complicated group with different and contradictory taxonomic treatments during the last century. We studied the phylogeny of the subgenus covering all existing taxonomic groups and their entire geographic distribution by analyzing ITS sequences of multiple accessions of more than 100 species.
Our data suggest a completely new classification within this subgenus, as nearly all sections appeared paraphyletic. Interestingly, several species in the study, such as A. rosenorum, A. stipitatum, and A. darwasicum, were found to occur with two quite different types of ITS sequences. This could be caused by the presence of intra-individual ITS polymorphism (i.e. paralogous ITS copies). However, extensive cloning of ITS amplicons did not reveal intra-individual ITS polymorphisms despite the hypothesized high level of hybridization in Melanocrommyum. In case of A. rosenorum, and A. stipitatum the populations, which form monophyletic groups in the ITS tree are also geographically clearly separated. Therefore we assume that they represent independent evolutionary lineages, which according to genetic distances clearly belong to different species that seem to have converged on similar phenotypes. In contrast, the topologically different ITS-groups of A. darwasicum do not show any geographical structure, as plants from single populations belong to these genetically quite different clades. The reason for this could either be these darwasicum-groups represent two different taxa, which converged morphologically, or ancient introgression followed by two-directional homogenization of the ITS loci mingled the picture. To test for ITS capture, we used random amplified polymorphic DNA (RAPD) fingerprinting. The RAPD profiles revealed a clear separation of individuals falling in different ITS groups, thus confirming the result from ITS analyses. The existence of morphologically cryptic and genetically clearly separated lineages within subg. Melanocrommyum, as well as the underlying mechanisms need further investigation.
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1 - Institute of Plant Genetics and Crop Research (IPK), Taxonomy & Evol. Biology, Gatersleben, D-06466, Germany
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM