Publications

Three new sesquiterpene-humulenes, (−)- asteriscunolides I (1), J (2) and (−)-(2Z,6E,9Z)-8-oxo-1α-acetoxy-2,6,9-humulatrien-12-oic acid (3) were isolated from the leaves-flowers of the Saharan medicinal plant Asteriscus graveolens along with six known compounds. The structures of the compounds were determined on the basis of spectroscopic mono and bidimensional NMR, mass spectrometry and by single-crystal X-ray diffraction. Compounds 1–3 were evaluated for cytotoxic assay, no significant activity was detected.

This paper explores the emergence of the terroirist social movement in Spain and the controversies arising from it. We assess its role in transforming the Spanish wine scene and wine regions from the combined perspective of rural and social movement studies. Spain boasts the largest surface area of vineyards and the largest volume of wine exports of any country, yet it also sells the cheapest wine and lacks wine zoning policies, which makes Spain unique among traditional wine-producing countries. Considering this situation, a group of terroir-driven winemakers are challenging the Spanish industrial wine establishment. They have built networks in rural areas throughout the country and are actively involved in local grassroots movements, aiming to produce quality wines with added value, recover neglected wine regions and grape varieties, and reinstate traditional wine culture. While the movement displays certain elite and populist tendencies, it remains radical in its attempt to challenge a deep-seated economic model dominated by large companies with a powerful lobby that influences the government.

[Aim] To test a prediction derived from island biogeographical theory that in situ speciation should make an increasingly important contribution to community assembly as islands age. This prediction is tested on estimated biogeographical histories from Mauritius (approximately 9 Myr) and Reunion (approximately 5 Myr). We additionally investigate the evolutionary dynamics of insect flight loss, as the loss of flight in island lineages can influence patterns of diversification. [Location] Mascarene Islands; Southwest Indian Ocean. [Taxon] Weevils. [Methods] Up to five individuals of each taxonomically described species sampled within each sampling site were sequenced for the mitochondrial gene Cytochrome Oxidase II to delimit operational taxonomic units (OTUs). OTUs were further sequenced for the nuclear genes Arginine Kinase, Histone 3 and ribosomal 28s, to reconstruct the phylogenetic history of the group. Timings of colonization and in situ speciation events were estimated with beast2. [Results] Our results support the hypothesis that present-day species richness on the older island of Mauritius is largely the result of in situ speciation, with few colonization events, of which all but the most basal are recent. In contrast, Reunion presents a more uniform temporal spectrum of colonization times. Flight loss has evolved convergently at least five times, and speciation events associated with flight loss are significantly younger than speciation events that have not resulted in flight loss. [Main conclusions] Patterns of community assembly on the islands of Mauritius and Reunion fit a model where the addition of new species and species turnover is increasingly dominated by in situ speciation as an island community matures. Repeated flight loss indicates selection for flightlessness, with the young age of flightless lineages suggesting higher extinction rates over longer evolutionary time-scales and little influence on present-day species richness.

Anagenesis and cladogenesis are fundamental evolutionary concepts, but are increasingly being adopted as speciation models in the field of island biogeography. Here, we review the origin of the terms ‘anagenetic’ and ‘cladogenetic’ speciation, critique their utility, and finally suggest alternative terminology that better describes the geographical relationships of insular sister species.

A latitudinal diversity gradient towards the tropics appears as one most recurrent patterns in ecology, but the mechanisms underlying this pattern remain an area of controversy. In angiosperms, the tropical conservatism hypothesis proposes that most groups originated in the tropics and are adapted to a tropical climatic regime, and that relatively few species have evolved physiological adaptations to cold, dry or unpredictable climates. This mechanism is, however, unlikely to apply across land plants, and in particular, to liverworts, a group of about 7500 species, whose ability to withstand cold much better than their tracheophyte counterparts is at odds with the tropical conservatism hypothesis. Molecular dating, diversification rate analyses and ancestral area reconstructions were employed to explore the evolutionary mechanisms that account for the latitudinal diversity gradient in liverworts. As opposed to angiosperms, tropical liverwort genera are not older than their extra-tropical counterparts (median stem age of tropical and extra-tropical liverwort genera of 24.35 ± 39.65 Ma and 39.57 ± 49.07 Ma, respectively), weakening the ‘time for speciation hypothesis’. Models of ancestral area reconstructions with equal migration rates between tropical and extra-tropical regions outperformed models with asymmetrical migration rates in either direction. The symmetry and intensity of migrations between tropical and extra-tropical regions suggested by the lack of resolution in ancestral area reconstructions towards the deepest nodes are at odds with the tropical niche conservatism hypothesis. In turn, tropical genera exhibited significantly higher net diversification rates than extra-tropical ones, suggesting that the observed latitudinal diversity gradient results from either higher extinction rates in extra-tropical lineages or higher speciation rates in the tropics. We discuss a series of experiments to help deciphering the underlying evolutionary mechanisms.

[Aim] Trees represent striking examples of habitat islands, with various degrees of spatial isolation and evolving properties during their life cycle. Here, we investigate whether changes in habitat conditions, dispersal limitations or competition cause variation in patterns of epiphytic species richness and turnover. [Location] Madeira island. [Taxon] Bryophytes. Methods: Using linear mixed effect models, we test whether species richness exhibits a monotonic or hump-shaped relationship with time. Two groups of host-tree species, late- and early-successional, were considered. We further identify the mechanisms explaining the observed variation in species composition by dividing beta diversity into its nestedness (β) and turnover (β) components and correlating them with tree age and geographical distance among trees. [Results] The best-fit models all included tree age (T), but its quadratic term (T) and tree height (H, here a surrogate of area) were not systematically included. β, but not β, correlated with host-tree age, and both β and β correlated with geographical distance. [Main conclusions] Tree age was consistently included in all of the best-fit models, reflecting the progressive increase in epiphyte bryophyte species richness through time. The limited contribution of T and H to the best models suggests that competition for space is not a key factor on mature trees. The correlation of β, but not β, with host-tree age, and of β and β with distance among trees, suggests that variation in species composition is caused by (1) temporal community shifts due to allogenic drivers and (2) dispersal limitations, which are reflected by the higher similarity of the epiphyte communities on clustered trees rather than by an increasing probability of colonization with tree age. Since actual ancient laurel forests may no longer exist in Madeira, the conservation of clusters of late-successional trees, enhancing connectivity at small spatial scales, is of utmost importance for the conservation and recovery of the unique laurel forest epiphytic flora.

Flavonoids are phenolic substances that appear to exert beneficial effects in several chronic diseases, including cancer. Structure-activity relationships of the cytotoxic activity of a series of flavonols and their 3-methyl ether derivatives established that 3′-hydroxy-3,4′-dimethoxyflavone (flavonoid 11) displayed strong cytotoxicity against human leukaemia cell lines (HL-60, U-937 and MOLT-3), and cells that over-express the anti-apoptotic proteins, Bcl-2 and Bcl-x, and against P-glycoprotein-overexpressing K-562/ADR cells. This compound induced G-M cell cycle arrest and it was a potent apoptotic inducer on HL-60, MOLT-3, U-937 and U-937/Bcl-2 cell lines. Cell death was (i) mediated by caspase activation, since it was prevented by the non-specific caspase inhibitor z-VAD-fmk and reduced by a selective caspase-9 inhibitor, (ii) associated with cytochrome c release, the dissipation of the inner mitochondrial membrane potential (ΔΨ) and the activation of the mitogen-activated protein kinase pathway and (iii) partially blocked by the inhibition of c-jun NH terminal kinases/stress activated protein kinases (JNK/SAPK) signalling and by the free-radical scavenger N-acetyl-L-cysteine.

Study of the aerial parts of the two species of Ageratina: A. dictyoneura and A. illita afforded four new ent-labdane diterpenoids (1–4). Two known labdanes: 2β,3α,15-trihydroxy-ent-labd-7-ene (5), and 2β,3α-trihydroxy-ent-labd-7-en-15-oic acid (6); two sesquiterpene lactones: 8β-hydroxy-β-cyclocostunolide (7) and eupatoriopicrin (8), one benzofuran, and six flavonoids were also isolated. Their chemical structures were determined based on extensive spectroscopic study, comparison with reported data and chemical transformations. The cytotoxicity of the new ent-labdane diterpenoids 1–3, sesquiterpene lactone 7, and the flavonoid: quercetin 3,7-dimethylether were assessed against the human myeloid leukemia U-937 cell line and found that compound 7 and quercetin 3,7-dimethylether were cytotoxic against this cell line.

The generation and fate of 2,3,6-icosa-O-methyl-β-cyclomaltoheptaos-6-O-yl radical under reductive conditions is described. Two radical cascade reactions are involved: the main one is triggered by a 1,8-HAT of the hydrogen at 5C. The radical can reach the anomeric hydrogen at 1C three sugar units ahead using a six-step sequence. The different hydrogen donor ability of the group 14 hydrides permits one to selectively stop the cascade at 5C, 2C, and 4C to obtain β-CD with a β-l-Idop unit, acyclic hepta-, and hexa-saccharide structures, respectively.