@article {29087, title = {Explosive radiation in high Andean Hypericum{\textendash} Rates of diversification among New World lineages}, journal = {Frontiers in Genetics}, volume = {4}, year = {2013}, pages = {175}, abstract = {

The p\áramos, high-elevation Andean grasslands ranging from ca. 2800m to the snow line, harbor one of the fastest evolving biomes worldwide since their appearance in the northern Andes 3\–5 million years (Ma) ago. Hypericum (St. John\’s wort), with over 65\% of its Neotropical species, has a center of diversity in these high Mountain ecosystems. Using nuclear rDNA internal transcribed spacer (ITS) sequences of a broad sample of New World Hypericum species we investigate phylogenetic patterns, estimate divergence times, and provide the first insights into diversification rates within the genus in the Neotropics. Two lineages appear to have independently dispersed into South America around 3.5 Ma ago, one of which has radiated in the p\áramos (Brathys). We find strong support for the polyphyly of section Trigynobrathys, several species of which group within Brathys, while others are found in temperate lowland South America (Trigynobrathys s.str.). All p\áramo species of Hypericum group in one clade. Within these p\áramo Hypericum species enormous phenotypic evolution has taken place (life forms from arborescent to prostrate shrubs) evidently in a short time frame. We hypothesize multiple mechanisms to be responsible for the low differentiation in the ITS region contrary to the high morphological diversity found in Hypericum in the p\áramos. Amongst these may be ongoing hybridization and incomplete lineage sorting, as well as the putative adaptive radiation, which can explain the contrast between phenotypic diversity and the close phylogenetic relationships.

}, isbn = {- 1664-8021}, doi = {10.3389/fgene.2013.00175}, url = {http://www.frontiersin.org/Journal/Abstract.aspx?s=1254\&name=evolutionary_and_population_genetics\&ART_DOI=10.3389/fgene.2013.00175}, author = {N{\"u}rk, Nicolai M. and Scheriau, Charlotte and Madri{\~n}{\'a}n, Santiago} } @article {29088, title = {Molecular phylogenetics and morphological evolution of St. John{\textquoteright}s wort (Hypericum; Hypericaceae)}, journal = {Molecular Phylogenetics and EvolutionMolecular phylogenetics and evolution}, volume = {66}, number = {1}, year = {2013}, pages = {1--16}, edition = {08.09.2012}, abstract = {

Phylogenetic hypotheses for the large cosmopolitan genus Hypericum (St. John\‚\Ä\ôs wort) have previously been based on morphology, and molecular studies have thus far included only a few species. In this study, we used 360 sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA) for 206 species representing Hypericum (incl. Triadenum and Thornea) and three other genera of Hypericaceae to generate an explicit phylogenetic hypothesis for the genus using parsimony and model-based methods. The results indicate that the small genus Triadenum is nested in a clade within Hypericum containing most of the New World species. Sister to Hypericum is Thornea from Central America. Within Hypericum, three large clades and two smaller grades were found; these are based on their general morphology, especially characters used previously in taxonomy of the genus. Relative to the most recent classification, around 60\% of the sections of Hypericum were monophyletic. We used a Bayesian approach to reconstruct ancestral states of selected morphological characters, which resulted in recognition of characters that support major clades within the genus and a revised interpretation of morphological evolution in Hypericum. The shrubby habit represents the plesiomorphic state from which herbs evolved several times. Arborescent species have radiated convergently in high-elevation habitats in tropical Africa and South America.

}, keywords = {Character evolution, Hypericaceae, Internal transcribed spacer (ITS), Phylogeny, Thornea, Triadenum}, isbn = {1055-7903}, doi = {10.1016/j.ympev.2012.08.022}, url = {http://www.sciencedirect.com/science/article/pii/S1055790312003314?v=s5}, author = {N{\"u}rk, Nicolai M. and Madri{\~n}{\'a}n, Santiago and Carine, Mark A. and Chase, Mark W. and Blattner, Frank R.} } @article {29089, title = {Morphological and phytochemical diversity among Hypericum species of the Mediterranean basin}, journal = {Medicinal and Aromatic Plant Science and BiotechnologyMedicinal and Aromatic Plant Science and Biotechnology}, volume = {5}, number = {Special Issue 1}, year = {2011}, pages = {14--28}, author = {N{\"u}rk, Nicolai M. and Crockett, S. L.} } @article {29090, title = {Cladistic analysis of morphological characters in Hypericum (Hypericaceae)}, journal = {TaxonTaxon}, volume = {59}, number = {5}, year = {2010}, pages = {1495-1507}, abstract = {

Hypericum is a worldwide distributed genus with almost 500 species, including the medically used apomictic species H. perforatum. It is one of the few large plant genera where alpha taxonomy is nearly completed. To conduct a formal cladistic analysis of the genus, we coded 89 morphological characters for all described taxa, and analyzed the data with parsimony and Bayesian methods. The obtained trees indicate Hypericum to be monophyletic, if the monotypic genus Santomasia is included, and Lianthus as the sister group. The arrangement of the remaining genera of Hypericaceae included in the analysis is in congruence with molecular phylogenies. Apomorphic characters supporting the relationships of the genera are pointed out. The cladistic analysis revealed four groups within Hypericum: a basal grade containing Mediterranean species and three big clades containing most of the diversity of the genus. The borders of the Mediterranean Sea as part of the late Tethys Ocean are hypothesized as a probable area of origin for the genus. As indicated in the presented tree, a shrubby habit appears to be the ancestral state within Hypericum from which trees and herbs evolved, and apomixis originated at least three times independently within the genus.

}, keywords = {_nmn, biogeography, cladistic analysis, evolution, Hypericum, Phylogeny, St. John{\textquoteright}s wort}, url = {http://www.ingentaconnect.com/content/iapt/tax/2010/00000059/00000005/art00014}, author = {N{\"u}rk, Nicolai M. and Blattner, F. R.} }