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Reticulate phylogenetics and phytogeographical structure of Heliosperma (Sileneae, Caryophyllaceae) inferred from chloroplast and nuclear DNA sequences
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Systematic Botany.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Systematic Botany.
2007 (English)In: Molecular Phylogenetics and Evolution, ISSN 1055-7903, E-ISSN 1095-9513, Vol. 43, no 1, 140-155 p.Article in journal (Refereed) Published
Abstract [en]

The Balkan Peninsula is known to be one of the most diverse and species-rich parts of Europe, but its biota has gained much less attention in phylogenetic and evolutionary studies compared to other southern European mountain systems. We used nuclear ribosomal internal transcribed spacer (ITS) sequences and intron sequences of the chloroplast gene rps16 to examine phylogenetic and biogeographical patterns within the genus Heliosperma (Sileneae, Caryophyllaceae). The ITS and rps16 intron sequences both support monophyly of Heliosperma, but the data are not conclusive with regard to its exact origin. Three strongly supported clades are found in both data sets, corresponding to Heliosperma alpestre, Heliosperma macranthum and the Heliosperma pusillum clade, including all other taxa. The interrelationships among these three differ between the nuclear and the plastid data sets. Hierarchical relationships within the H. pusillum clade are poorly resolved by the ITS data, but the rps16 intron sequences form two well-supported clades which are geographically, rather than taxonomically, correlated. A similar geographical structure is found in the ITS data, when analyzed with the NeighbourNet method. The apparent rate of change within Heliosperma is slightly higher for rps16 as compared to ITS. In contrast, in the Sileneae outgroup, ITS substitution rates are more than twice as high as those for rps16, a situation more in agreement with what has been found in other rate comparisons of noncoding cpDNA and ITS. Unlike most other Sileneae ITS sequences, the H. pusillum group sequences display extensive polymorphism. A possible explanation to these patterns is extensive hybridization and gene flow within Heliosperma, which together with concerted evolution may have eradicated the ancient divergence suggested by the rps16 data. The morphological differentiation into high elevation, mainly widely distributed taxa, and low elevation narrow endemics is not correlated with the molecular data, and is possibly a result of ecological differentiation.

Place, publisher, year, edition, pages
2007. Vol. 43, no 1, 140-155 p.
Keyword [en]
Heliosperma, Ixoca, Balkan biogeography, ITS, rps16, Reticulate evolution
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-96103DOI: 10.1016/j.ympev.2006.11.003ISI: 000245936000011PubMedID: 17188521OAI: oai:DiVA.org:uu-96103DiVA: diva2:170568
Available from: 2007-09-05 Created: 2007-09-05 Last updated: 2011-02-02Bibliographically approved
In thesis
1. Taxonomy and Reticulate Phylogeny of Heliosperma and Related Genera (Sileneae, Caryophyllaceae)
Open this publication in new window or tab >>Taxonomy and Reticulate Phylogeny of Heliosperma and Related Genera (Sileneae, Caryophyllaceae)
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Heliosperma (nom. cons prop.) comprises 15—20 taxa, most of them endemic to the Balkan Peninsula. DNA sequences from the chloroplast (rps16 intron, psbE-petG spacer) and the nuclear genome (ITS and four putatively unlinked RNA polymerase genes) are used to elucidate phylogenetic relationships within Heliosperma, and its position within Sileneae. Three main lineages are found within Heliosperma: Heliosperma alpestre, H. macranthum and the H. pusillum-clade. The relationships among the lineages differ between the plastid and the nuclear trees. Relative dates are used to discriminate among inter- and intralineage processes causing such incongruences, and ancient homoploid hybridisation is the most likely explanation.

The chloroplast data strongly support two, geographically correlated clades in the H. pusillum-group, whereas the relationships appear poorly resolved by the ITS data, when analysed under a phylogenetic tree model. However, a network analysis finds a geographic structuring similar to that in the chloroplast data. Ancient vicariant divergence followed by hybridisation events best explains the observed pattern. The morphological and taxonomical diversity in the H. pusillum-group is possibly ecology-induced, and is not correlated with the molecular data.

Phylogenetic patterns regarding the origin of Heliosperma are complicated, probably influenced by reticulate and sorting events. At least two ancient lineages have been involved in its evolution, one most closely related to Viscaria/Atocion and the other to Eudianthe/Petrocoptis.

Atocion and Viscaria are sister genera, most species-rich on the Balkans, and including six/three species. Phylogenies do not support their traditional classification, and provide a framework for a taxonomic revision. Atocion compactum is found in three different positions in the chloroplast tree, and in a single clade in the nuclear gene trees. Using relative dates we demonstrate that hybridisation with subsequent chloroplast capture is a feasible explanation for the pattern observed. This, and other observed reticulate patterns, highlights the importance of hybridisation in plant evolution.

Place, publisher, year, edition, pages
Uppsala: Universitetsbiblioteket, 2007. 34 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 328
Sileneae, Silene, Heliosperma, Atocion, Viscaria, taxonomy, phylogenetics, relative dating, reticulate evolution, chloroplast capture, homoploid hybridisation, BEAST, r8s, PATHd8, Prometheus, RPA2, RPB2, RPD2a, RPD2b, Balkan Peninsula, endemics
National Category
Biological Systematics
urn:nbn:se:uu:diva-8171 (URN)978-91-554-6946-7 (ISBN)
Public defence
2007-09-27, Lindahlsalen, EBC, Norbyvägeb 18A, Uppsala, 10:00
Available from: 2007-09-05 Created: 2007-09-05 Last updated: 2010-07-07Bibliographically approved

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