Cam17

Content

Systematics

This huge and well-supported clade, with some 195 species/subspecies of Campanula s.l., including the
genus’ type species (Campanula latifolia L.), remains globally unresolved. In most cases, individuals from the same species were grouped as sisters, but there were also cases with high diversity such as C. sibirica, C. barbata, C. spatulata, or C. lingulata, where this study can guide future phylogeographic/speciation studies.

Several technical and biological explanations have been proposed for the phylogenetic inference of non-bifurcating trees, with soft or hard polytomies, including gene choice, rapid diversification of lineages, or reticulate evolution (Wendel & Doyle 1998, Doyle & Davis 1998. The petD region has been used to resolve successfully phylogenetic patterns at different taxonomic levels (Borsch & Quandt 2009, Löhne & Borsch 2005, Korotkova & al. 2009). Overall, the polytomy of the Cam17 lineage has also been exemplified by the trnLF (Roquet & al. 2008) and rpl16 (unpublished data) regions. While the combined use of different markers poorly resolved such lineage (Haberle & al. 2009, Wendling & al. 2011), it has to be awaited how the addition of information from genomic regions with high level of hierarchical phylogenetic signal will improve the situation. Organellar and nuclear genomic compartments should thereby be analyzed independently to test for possible incongruence.

At the organismal level, the inferred timing of lineage diversification, combined with the accumulation of taxa in particular regions of the eastern Mediterranean and Middle-East (most accessions in Cam17 come from Greece, Turkey, and the Caucasus), would support recent patterns of hyper-diversification. This hypothesis needs to be tested with comprehensive biogeographic methods and estimations of lineage through time accumulation for the entire clade. Finally, the occurrence of particular events known to disrupt phylogenetic bifurcation, such as incomplete sorting of lineages, or hybridization and introgression associated or not with genome duplication, cannot be ruled-out in the present case. Overall, we feel that a combination of the aforementioned factors (low phylogenetic information and noise) might provide the most likely explanation for the current comb-like structure of clade Cam17.


From: Mansion & al. (2012: 19)

References


Borsch T. & Quandt D. 2009: Mutational dynamics and phylogenetic utility of noncoding chloroplast DNA. – Plant Syst. Evol. 282:169–199
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Doyle J.J. & Davis J.I. 1998: Homology in molecular phylogenetics: a parsimony perspective. Pp 101–131. In: Soltis D.E., Soltis P.M. & Doyle J.J. (eds.); Molecular systematics of plants II DNA sequencing. – Boston: Kluwer Academic.

Haberle R.C., Dang A., Lee T., Penaflor C., Cortes-Burns H. & al. 2009: Taxonomic and biogeographic implications of a phylogenetic analysis of the Campanulaceae based on three chloroplast genes. – Taxon 58:715–734.

Korotkova N., Schneider J.V., Quandt D., Worberg A., Zizka G., & al. 2009: Phylogeny of the eudicot order Malpighiales: analysis of a recalcitrant clade with sequences of the petD group II intron. – Plant Syst. Evol. 282:201–228.

Löhne C. & Borsch T. 2005: Molecular evolution and phylogenetic utility of the petD group II intron: A case study in basal angiosperms. – Mol. Biol. Evol. 22:317–323.

Mansion G., Parolly G., Crowl A.A., Mavrodiev E., Cellinese N., Oanesian M., Fraunhofer K., Kamari G., Phitos D., Haberle R., Akaydin G., Ikinci N., Raus T. & Borsch T. 2012: How to Handle Speciose Clades? Mass Taxon-Sampling as a Strategy towards Illuminating the Natural History of Campanula (Campanuloideae). – PLoS ONE 7 (11).

Roquet C., Saez L., Aldasoro JJ., Susanna A., Alarcon ML. & al. 2008: Natural delineation, molecular phylogeny and floral evolution in Campanula. – Syst. Bot. 33: 203–217.

Wendel J.F. & Doyle J.J. 1998: Phylogenetic incongruence: window into genome history and molecular evolution. – Pp 265–296. In: Soltis D.E., Soltis P.M. & Doyle J.J. (eds.), Molecular systematics of plants II DNA sequencing. – Boston: Kluwer Academic.

Wendling B.M., Galbreath K.E. & DeChaine E.G. 2011: Resolving the evolutionary history of Campanula (Campanulaceae) in Western North America. – PLoS ONE 6 (9).

Synonymy

Cam17