Rapid diversification of Tragopogon and ecological associates in Eurasia.

Tragopogon comprises approximately 150 described species distributed throughout Eurasia from Ireland and the UK to India and China with a few species in North Africa. Most of the species diversity is found in Eastern Europe to Western Asia. Previous phylogenetic analyses identified several major clades, generally corresponding to recognized taxonomic sections, although relationships both among these clades and among species within clades remain largely unresolved. These patterns are consistent with rapid diversification following the origin of Tragopogon, and this study addresses the timing and rate of diversification in Tragopogon. Using BEAST to simultaneously estimate a phylogeny and divergence times, we estimate the age of a major split and subsequent rapid divergence within Tragopogon to be ~2.6 Ma (and 1.7-5.4 Ma using various clock estimates). Based on the age estimates obtained with BEAST (HPD 1.7-5.4 Ma) for the origin of crown group Tragopogon and 200 estimated species (to accommodate a large number of cryptic species), the diversification rate of Tragopogon is approximately 0.84-2.71 species/Myr for the crown group, assuming low levels of extinction. This estimate is comparable in rate to a rapid Eurasian radiation in Dianthus (0.66-3.89 species/Myr), which occurs in the same or similar habitats. Using available data, we show that subclades of various plant taxa that occur in the same semi-arid habitats of Eurasia also represent rapid radiations occurring during roughly the same window of time (1.7-5.4 Ma), suggesting similar causal events. However, not all species-rich plant genera from the same habitats diverged at the same time, or at the same tempo. Radiations of several other clades in this same habitat (e.g. Campanula, Knautia, Scabiosa) occurred at earlier dates (45-4.28 Ma). Existing phylogenetic data and diversification estimates therefore indicate that, although some elements of these semi-arid communities radiated during the Plio-Pleistocene period, other clades sharing the same habitat appear to have diversified earlier.

Genetic variation in Mediterranean Helichrysum italicum (Asteraceae; Gnaphalieae): do disjunct populations of subsp. microphyllum have a common origin?

The yellow-flowered everlasting daisy Helichrysum italicum (Asteraceae, Gnaphalieae) is widely distributed in the Mediterranean basin, where it grows in continuous and widespread populations in diverse open habitats. Helichrysum italicum subsp. microphyllum has a disjunct distribution in the Balearic Islands (Majorca and Dragonera), Corsica, Sardinia, Crete and Cyprus. Numerous morphological intermediates between subsp. italicum and subsp. microphyllum are known from Corsica, where the two subspecies co-occur. The aims of the study were to investigate if subsp. microphyllum has a common origin, constituting an independent gene pool from subsp. italicum, or if the morphological differences between subsp. microphyllum and subsp. italicum have arisen independently in different locations from a common wider gene pool. Our analyses of AFLP, cpDNA sequences and morphological characters show that there is geographic structure to the genetic variation within H. italicum, with eastern and western Mediterranean groups, which do not correspond with the division into subsp. microphyllum and subsp. italicum as currently circumscribed. Local selection on quantitative trait loci provides sufficient explanation for the morphological divergence observed and is consistent with genetic data. Within the western Mediterranean group of the species we found considerable polymorphism in chloroplast DNA sequences among and within some populations. Comparison with chloroplast DNA sequences from other Helichrysum species showed that some chloroplast haplotypes are shared across species.

Centaurea revisited: A molecular survey of the Jacea group.

BACKGROUND AND AIMS: The genus Centaurea has traditionally been considered to be a complicated taxon. No attempt at phylogenetic reconstruction has been made since recent revisions in circumscription, and previous reconstructions did not include a good representation of species. A new molecular survey is thus needed. METHODS: Phylogenetic analyses were conducted using sequences of the internal transcribed spacers (ITS) 1 and 2 and the 5.8S gene. Parsimony and Bayesian approaches were used. KEY RESULTS: A close correlation between geography and the phylogenetic tree based on ITS sequences was found in all the analyses, with three main groups being resolved: (1) comprising the most widely distributed circum-Mediterranean/Eurosiberian sections; (2) the western Mediterranean sections; and (3) the eastern Mediterranean and Irano-Turanian sections. The results show that the sectional classification in current use needs major revision, with many old sections being merged into larger ones. A large polytomy in the eastern Mediterranean clade suggests a rapid and recent speciation in this group. Some inconsistencies between morphology and molecular phylogeny may indicate that hybridization has played a major role in the evolution of the genus. CONCLUSIONS: Phylogenetic analysis of ITS has been useful in identifying the major lineages in the group, and unraveling many inconsistencies in the sectional classification. However, most recent groups in the eastern Mediterranean clade are not resolved and reticulation in the western Mediterranean group of sections makes phylogenetic relationships within these two groups somewhat obscure.

Molecular cytogenetics of Xeranthemum L. and related genera (Asteraceae, Cardueae).

Seven representatives of the genera Amphoricarpus, Chardinia, Siebera, and Xeranthemum, all of them closely related as demonstraded by molecular phylogeny, have been studied from a cytogenetic perspective. Morphometrical karyotype parameters were calculated and idiograms obtained. Fluorochrome banding was performed with chromomycin A (3) to identify GC-rich regions in the chromosomes. Fluorescence in situ hybridization allowed us to locate the sites of 18S-5.8S-26S and 5S rDNA. Silver nitrate staining was used to count the number of nucleoli and to detect the active nucleolar organizing regions. Systematic and evolutionary issues are addressed in the light of these data.

Multiple introductions from the Iberian peninsula are responsible for invasion of Crupina vulgaris in western North America.

• Crupina vulgaris is a relatively recent invader to grasslands and other open habitats in western North America. Like related Centaurea species, it was introduced from the Mediterranean region, where it does not exhibit ruderal behavior. Determining the number and sources of invasion founders allows fuller interpretation of colonization dynamics and recognition of potential intercontinental carriers, both critical factors for curbing the spread of invasive species. • We chose the molecular technique of random amplified polymorphic DNA (RAPD) to identify the number and sources of invasion founders from the eastern hemisphere, by comparing indigenous and invasive populations. • Our results indicated that the five North American populations derived from three or more successful invasion events whose founders originated in the Iberian peninsula. • Also inferred by the similarity clustering among eastern hemisphere populations is a more ancient origin of the genus to the east of the Mediterranean, a concept supported by the scarcity of suitable nonanthropic habitat in Spain. Its epizoochoric association with migratory movements of domestic herds suggests probable routes of migration first to southern Europe, then later to North America.