02659nas a2200169 4500008004100000245015800041210006900199300000700268490000700275520206500282100001802347700002202365700001502387700001702402700002102419856004902440 2015 eng d00aOligocene niche shift, Miocene diversification - Cold tolerance and accelerated speciation rates in the St. John's Worts (Hypericum, Hypericaceae)0 aOligocene niche shift Miocene diversification Cold tolerance and a800 v503 a

Background: Our aim is to understand the evolution of species-rich plant groups that shifted from tropical into cold/temperate biomes. It is well known that climate affects evolutionary processes, such as how fast species diversify, species range shifts, and species distributions. Many plant lineages may have gone extinct in the Northern Hemisphere due to Late Eocene climate cooling, while some tropical lineages may have adapted to temperate conditions and radiated; the hyper-diverse and geographically widespread genus Hypericum is one of these.

Results: To investigate the effect of macroecological niche shifts on evolutionary success we combine historical biogeography with analyses of diversification dynamics and climatic niche shifts in a phylogenetic framework. Hypericum evolved cold tolerance c. 30 million years ago, and successfully colonized all ice-free continents, where today ~500 species exist. The other members of Hypericaceae stayed in their tropical habitats and evolved into ~120 species. We identified a 15–20 million year lag between the initial change in temperature preference in Hypericum and subsequent diversification rate shifts in the Miocene.

Conclusions: Contrary to the dramatic niche shift early in the evolution of Hypericum most extant species occur in temperate climates including high elevations in the tropics. These cold/temperate niches are a distinctive characteristic of Hypericum. We conclude that the initial release from an evolutionary constraint (from tropical to temperate climates) is an important novelty in Hypericum. However, the initial shift in the adaptive landscape into colder climates appears to be a precondition, and may not be directly related to increased diversification rates. Instead, subsequent events of mountain formation and further climate cooling may better explain distribution patterns and species-richness in Hypericum. These findings exemplify important macroevolutionary patterns of plant diversification during large-scale global climate change.

1 aNürk, N., M.1 aUribe-Convers, S.1 aGehrke, B.1 aTank, D., C.1 aBlattner, F., R. uhttp://www.biomedcentral.com/1471-2148/15/8001944nas a2200217 4500008004100000245008600041210006900127300001400196490000700210520126900217653000901486653001701495653002301512653001401535653001401549653001401563653002201577100002301599700002101622856008301643 2010 eng d00aCladistic analysis of morphological characters in Hypericum (Hypericaceae)0 aCladistic analysis of morphological characters in iHypericumi Hy a1495-15070 v593 a

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.

10a_nmn10abiogeography10acladistic analysis10aevolution10aHypericum10aPhylogeny10aSt. John’s wort1 aNürk, Nicolai, M.1 aBlattner, F., R. uhttp://www.ingentaconnect.com/content/iapt/tax/2010/00000059/00000005/art00014