Publicaciones

[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.

Oceanic islands emerge lifeless from the seafloor and are separated from continents by long stretches of sea. Consequently, all their species had to overcome this stringent dispersal filter, making these islands ideal systems to study the biogeographic implications of long-distance dispersal (LDD). It has long been established that the capacity of plants to reach new islands is determined by specific traits of their diaspores, historically called dispersal syndromes. However, recent work has questioned to what extent such dispersal-related traits effectively influence plant distribution between islands. Here we evaluated whether plants bearing dispersal syndromes related to LDD ¿ i.e. anemochorous (structures that favour wind dispersal), thalassochorous (sea dispersal), endozoochorous (internal animal dispersal) and epizoochorous (external animal dispersal) syndromes ¿ occupy a greater number of islands than those with unspecialized diaspores by virtue of their increased dispersal ability. We focused on the native flora of the lowland xeric communities of the Canary Islands (531 species) and on the archipelago distribution of the species. We controlled for several key factors likely to affect the role of LDD syndromes in inter-island colonization, namely: island geodynamic history, colonization time and phylogenetic relationships among species. Our results clearly show that species bearing LDD syndromes have a wider distribution than species with unspecialized diaspores.

Islands harbour evolutionary and ecologically unique biota, which are currently disproportionately threatened by a multitude of anthropogenic factors, including habitat loss, invasive species and climate change. Native forests on oceanic islands are important refugia for endemic species, many of which are rare and highly threatened. Long-term monitoring schemes for those biota and ecosystems are urgently needed: (i) to provide quantitative baselines for detecting changes within island ecosystems, (ii) to evaluate the effectiveness of conservation and management actions, and (iii) to identify general ecological patterns and processes using multiple island systems as repeated ‘natural experiments’. In this contribution, we call for a Global Island Monitoring Scheme (GIMS) for monitoring the remaining native island forests, using bryophytes, vascular plants, selected groups of arthropods and vertebrates as model taxa. As a basis for the GIMS, we also present new, optimized monitoring protocols for bryophytes and arthropods that were developed based on former standardized inventory protocols. Effective inventorying and monitoring of native island forests will require: (i) permanent plots covering diverse ecological gradients (e.g. elevation, age of terrain, anthropogenic disturbance); (ii) a multiple-taxa approach that is based on standardized and replicable protocols; (iii) a common set of indicator taxa and community properties that are indicative of native island forests’ welfare, building on, and harmonized with existing sampling and monitoring efforts; (iv) capacity building and training of local researchers, collaboration and continuous dialogue with local stakeholders; and (v) long-term commitment by funding agencies to maintain a global network of native island forest monitoring plots.

[Background] Rhinorhipidae Lawrence, 1988 is an enigmatic beetle family represented by a single species, Rhinorhipus tamborinensis Lawrence, 1988, from Australia, with poorly established affinities near the superfamily Elateroidea (click beetles, soldier beetles and fireflies) or the more inclusive series (infraorder) Elateriformia. Its evolutionary position may inform the basal relationships of the suborder Polyphaga, the largest clade of Coleoptera. [Results] We analyzed four densely sampled DNA datasets of major coleopteran lineages for mitogenomes, rRNA genes and single copy nuclear genes. Additionally, genome sequencing was used for incorporation of R. tamborinensis into a set of 4220 orthologs for 24 terminals representing 12 polyphagan superfamilies. Topologies differed to various degrees, but all consistently refute the proposed placement of Rhinorhipidae in Elateroidea and instead indicate either sister relationships with other Elateriformia, frequently together with Nosodendridae, another divergent small family hitherto placed in Derodontoidea, or in an isolated position among the deepest lineages of Polyphaga. The phylogenomic analyses recovered Rhinorhipus in a sister position to all other Elateriformia composed of five superfamilies. Therefore, we erect the new superfamily Rhinorhipoidea Lawrence, 1988, stat. Nov., with the type-family Rhinorhipidae. The origins of the Rhinorhipidae were dated to the Upper Triassic/Lower Jurassic at the very early phase of polyphagan diversification. [Conclusions] Thus, Rhinorhipidae adds another example to several recently recognized ancient relict lineages which are interspersed within contemporaneous hugely species-rich lineages of Coleoptera.

From Brazil to the United Kingdom, 2016 was a critical year in global politics. Heritage, ethics and the way that archaeologists relate to the public were and will all be affected, and it is time to reflect critically on the phenomenon of ‘reactionary populism’ and how it affects the practice and theory of archaeology. ‘Reactionary populism’ can be defined as a political form that is anti-liberal in terms of identity politics (e.g. multiculturalism, abortion rights, minority rights, religious freedom), but liberal in economic policies. It is characterised by nationalism, racism and anti-intellectualism, and as Judith Butler states in a recent interview, it wants “to restore an earlier state of society, driven by nostalgia or a perceived loss of privilege” (Soloveitchik 2016). Our intention here is to argue that the liberal, multi-vocal model of the social sciences and the humanities is no longer a viable option. Instead, we ask our colleagues to embrace an archaeology that is ready to intervene in wider public debates not limited to issues of heritage or of local relevance, is not afraid of defending its expert knowledge in the public arena, and is committed to reflective, critical teaching.

Morphometrics, the assignment of quantities to biological shapes, is a powerful tool to address taxonomic, evolutionary, functional and developmental questions. We propose a novel method for shape quantification of complex modular architecture in thalloid plants, whose extremely reduced morphologies, combined with the lack of a formal framework for thallus description, have long rendered taxonomic and evolutionary studies extremely challenging. Using graph theory, thalli are described as hierarchical series of nodes and edges, allowing for accurate, homologous and repeatable measurements of widths, lengths and angles. The computer program MorphoSnake was developed to extract the skeleton and contours of a thallus and automatically acquire, at each level of organization, width, length, angle and sinuosity measurements. Through the quantification of leaf architecture in Hymenophyllum ferns (Polypodiopsida) and a fully worked example of integrative taxonomy in the taxonomically challenging thalloid liverwort genus Riccardia, we show that MorphoSnake is applicable to all ramified plants. This new possibility of acquiring large numbers of quantitative traits in plants with complex modular architectures opens new perspectives of applications, from the development of rapid species identification tools to evolutionary analyses of adaptive plasticity.