Andrea Melichárková1, Stanislav Španiel1,2, Karol Marhold1,2, Bogdan-Iuliu Hurdu3, Anton Drescher4, Judita Zozomová-Lihová1. 1. Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 23, Bratislava, Slovakia. 2. Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, CZ-128 01, Prague, Czech Republic. 3. Institute of Biological Research, National Institute of Research and Development for Biological Sciences, 48 Republicii Street, 400015, Cluj-Napoca, Romania. 4. Institut für Pflanzenwissenschaften der Universität Graz - Herbarium GZU, Holteigasse 6, A-8010, Graz, Austria.
Abstract
PREMISE: Disjunct distributions have been commonly observed in mountain plant species and have stimulated phylogeographic and phylogenetic research. Here we studied Alyssum repens, a member of the polyploid species complex A. montanum-A. repens, which exhibits SE Alpine-Carpathian disjunctions with a large elevational span and consists of diploid and tetraploid populations. We aimed to investigate the species' genetic and cytotype structure in the context of its distribution patterns, to elucidate the polyploid origins and to propose an appropriate taxonomic treatment. METHODS: We combined AFLP fingerprinting markers, sequence variation of the highly repetitive ITS region of rDNA and the low-copy DET1 nuclear gene, genome size, and morphometric data. RESULTS: We identified four geographically structured genetic lineages. One consisted of diploid populations from the foothills of the Southeastern Alps and neighboring regions, and the three others were allopatric montane to alpine groups comprising diploids and tetraploids growing in the Southeastern Carpathians and the Apuseni Mts. in Romania. CONCLUSIONS: We inferred a vicariance scenario associated with Quaternary climatic oscillations, accompanied by one auto- and two allopolyploidization events most likely involving a northern Balkan relative. Whereas genetic differentiation and allopatric distribution would favor the taxonomic splitting of this species, the genetic lineages largely lack morphological distinguishability, and their ecological, cytotype and genome size divergence is only partial. Even though we probably face here a case of incipient speciation, we propose to maintain the current taxonomic treatment of Alyssum repens as a single, albeit variable, species.
PREMISE: Disjunct distributions have been commonly observed in mountain plant species and have stimulated phylogeographic and phylogenetic research. Here we studied Alyssum repens, a member of the polyploid species complex A. montanum-A. repens, which exhibits SE Alpine-Carpathian disjunctions with a large elevational span and consists of diploid and tetraploid populations. We aimed to investigate the species' genetic and cytotype structure in the context of its distribution patterns, to elucidate the polyploid origins and to propose an appropriate taxonomic treatment. METHODS: We combined AFLP fingerprinting markers, sequence variation of the highly repetitive ITS region of rDNA and the low-copy DET1 nuclear gene, genome size, and morphometric data. RESULTS: We identified four geographically structured genetic lineages. One consisted of diploid populations from the foothills of the Southeastern Alps and neighboring regions, and the three others were allopatric montane to alpine groups comprising diploids and tetraploids growing in the Southeastern Carpathians and the Apuseni Mts. in Romania. CONCLUSIONS: We inferred a vicariance scenario associated with Quaternary climatic oscillations, accompanied by one auto- and two allopolyploidization events most likely involving a northern Balkan relative. Whereas genetic differentiation and allopatric distribution would favor the taxonomic splitting of this species, the genetic lineages largely lack morphological distinguishability, and their ecological, cytotype and genome size divergence is only partial. Even though we probably face here a case of incipient speciation, we propose to maintain the current taxonomic treatment of Alyssum repens as a single, albeit variable, species.