ABSTRACT
Understanding transcontinental biogeographic patterns has been one of the main foci of the field of biogeography. While multiple explanations for transcontinental disjunctions have been proposed, little is still known about the relative importance of intrinsic and extrinsic traits for the diversification dynamics of disjunct taxa. Here, we study the evolutionary history of the genus Picris L. (Compositae), a great model for investigating the diversification dynamics of transoceanic bipolar disjunct organisms. Ancestral state reconstructions indicate that the most recent common ancestor (MRCA) of Picris was a semelparous and heterocarpic herb that lived in unpredictable environments of North Africa and West Asia. Diversification analyses suggest a significant shift in speciation ca. 1 million years ago, likely associated with the onset of the mid-Pleistocene revolution. Longevity characters are correlated with the evolution of particular fruit types and with environmental conditions. Heterocarpic species are mostly semelparous herbs strongly linked with unpredictable habitats, while homocarpic taxa are mostly iteroparous plants occurring in predictable environments. Binary-state speciation and extinction analyses suggest that homocarpy, iteroparity, and habitats predictability accelerate diversification. Although the combination of homocarpy and iteroparity evolved in several lineages, only members of the P. hieracioides group were able to colonise Eurasia and expand to Australia by transoceanic dispersal. Those findings indicate that large-scale colonisation events depend on a complex interplay of intrinsic and extrinsic factors.
Subject(s)
Asteraceae/classification , Biodiversity , Climate , Africa, Northern , Asia , Australia , Bayes Theorem , Models, Biological , Phenotype , Phylogeny , Phylogeography , Quantitative Trait, HeritableABSTRACT
The Czech botanist Frantisek Nábelek (1884-1965) explored the Middle East in 1909-1910, visiting what are now Israel, Palestine, Jordan, Syria, Lebanon, Iraq, Bahrain, Iran and Turkey. He described four new genera, 78 species, 69 varieties and 38 forms of vascular plants, most of these in his work Iter Turcico-Persicum (1923-1929). The main herbarium collection of Iter Turcico-Persicum comprises 4163 collection numbers (some with duplicates), altogether 6465 specimens. It is currently deposited in the herbarium SAV. In addition, some fragments and duplicates are found in B, E, W and WU. The whole collection at SAV was recently digitized and both images and metadata are available via web portal www.nabelek.sav.sk, and through JSTOR Global Plants and the Biological Collection Access Service. Most localities were georeferenced and the web portal provides a mapping facility. Annotation of specimens is available via the AnnoSys facility. For each specimen a CETAF stable identifier is provided enabling the correct reference to the image and metadata.
ABSTRACT
The plastid matK gene, trnL/F spacer, and nuclear rDNA ITS were sequenced for 36 species of Leontodon and 29 taxa of related genera of tribe Lactuceae. Phylogenetic relationships inferred from the independent and combined data are largely congruent and reveal that Leontodon sensu lato (s.l.) as presently defined is diphyletic: L. subgenus Leontodon forms a clade with Helminthotheca, Picris and Hypochaeris as sister genera, whereas L. subgenus Oporinia appears as a separate clade with strong bootstrap support and is thus better treated as a separate genus. Previous sectional classifications of Leontodon s.l. are considered in the light of DNA and additional morphological and karyological data. Support is presented for a core group of Hypochaeridinae sensu stricto (s.s.) with the two clades of Leontodon s.l., Helminthotheca, Picris, and Hypochaeris, whereas Urospermum, Hyoseris, Aposeris, and Rhagadiolus appear to be positioned more distantly.
