Giants and dwarfs: molecular phylogenies reveal multiple origins of annual spurges within Euphorbia subg. Esula

Euphorbia (Euphorbiaceae) comprises over 2150 species and is thus the second-largest genus of flowering plants. In Europe, it is represented by more than 100 species with highest diversity in the Mediterranean area; the majority of taxa belong to subgenus Esula Pers., including about 500 taxa. The few available phylogenetic studies yielded contrasting results regarding the monophyly of subg. Esula, and the phylogenetic relationships among its constituents remain poorly understood. We have sampled DNA sequences from the nuclear ribosomal internal transcribed spacer (ITS) and the plastid trnT-trnF region from about 100, predominantly European taxa of subg. Esula in order to infer its phylogenetic history. The plastid data support monophyly of subg. Esula whereas the ITS phylogeny, which is generally less resolved, is indecisive in this respect. Although some major clades have partly incongruent positions in the ITS and plastid phylogenies, the taxonomic content of the major terminal clades is congruent in both trees. As traditional sectional delimitations are largely not corroborated, an improved classification is proposed. Character state reconstruction illustrates that the annual life form developed independently several times in different clades of subgenus Esula from perennial ancestors, and that several morphological traits used in previous classifications of Euphorbia developed in parallel in different lineages.     

Phylogenetics and taxonomy of the New World leafy spurges,Euphorbia section Tithymalus (Euphorbiaceae)

The 480 species of leafy spurges, Euphorbia subgenus Esula, represent the main temperate radiation in the large genus Euphorbia. This group is distributed primarily in temperate Eurasia, but with smaller, disjunct centres of diversity in the mountains of the Old World tropics, in temperate southern Africa and in the New World. The majority of New World diversity (32 species) occurs in a single section, section Tithymalus. We analysed sequences of the nrITS and plastid ndhF, trnH‐psbA, trnS‐trnG and trnD‐trnT regions to reconstruct the phylogeny of section Tithymalus and to examine the origins and diversification of the species native to the New World. Our results indicate that the New World species of section Tithymalus form a clade that is sister to the widespread, weedy E. peplus. The New World species fall into two primary groups: a ‘northern annual clade’ from eastern North America and a diverse clade of both annual and perennial species that is divided into three subgroups. Within the second group, there is a small ‘southern annual clade’ from Texas and northern Mexico, a perennial ‘Brachycera clade’ from the western United States and northern Mexico, and a perennial ‘Esuliformis clade’ from montane areas of Mexico, Guatemala, Honduras and the Caribbean island of Hispaniola. Ancestral state reconstructions indicate that the annual habit probably evolved in the ancestor of E. peplus and the New World clade, with a subsequent reversal to the perennial habit. In conjunction with this phylogenetic framework, the New World species of section Tithymalus are comprehensively reviewed. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 191–228.     

Contrasting climate signals across a Scots pine (Pinus sylvestris L.) tree-ring network in the Middle Volga (European Russia)

Since the late-19th century, the Middle Volga has played a major role in the supplying grains and other agricultural products to European Russia. The study area is located in the south of sub-boreal forest in the north and in the forest-steppe in the south. Due to large seasonal differences in rainfall, agriculture in the region, especially in its southern part, strongly depends on hydroclimate variability. According to climate model forecasts, the frequency and intensity of droughts in the Middle Volga are expected to increase due to ongoing warming. Here we introduce 16 new Scots pine tree ring width (TRW) chronologies (Pinus sylvestris L.) from the region and use a dendroclimatological approach to determine what climatic factors drive radial growth. Our analysis revealed contrasting climate signals across the network of sites with chronologies from the north showing weak correlation with May temperature and precipitation (r = −0.27 and r = 0.28, respectively), while the southern sites demonstrated stronger relationships with climate in the first half of the vegetation season (May to July temperature, r = −0.26 to −0.43; May and July precipitation, r = 0.29–0.35). The northern sites did not demonstrate a strong growth response to the self-calibrated Palmer drought severity index (scPDSI) whereas the southern group was more drought sensitive had a strong drought response and positively correlates with scPDSI for the period from previous July to the current October (r = 0.27–0.56). Based on this strong relationship between southern TRW and scPDSI we reconstruct June-September scPDSI using the most sensitive sites (T04S, T06S, T08S) for the period from 1830 to 2014. The model explains 31% of variance. Our reconstruction shows droughts in 19th century: in 1831–33, 1851, 1853, 1859, 1863–65, 1880, 1891–92, 1897–98 and in 20–21th centuries: in 1906, 1921, 1936, 1939, 1967, 1975, 1996, 2010.     

Is evolution faster at ecotones? A test using rates and tempo of diet transitions in Neotropical Sigmodontinae (Rodentia,Cricetidae)

We evaluated whether evolution is faster at ecotones as niche shifts may be needed to persist under unstable environment. We mapped diet evolution along the evolutionary history of 350 sigmodontine species. Mapping was used in three new tip‐based metrics of trait evolution – Transition Rates, Stasis Time, and Last Transition Time – which were spatialized at the assemblage level (aTR, aST, aTL). Assemblages were obtained by superimposing range maps on points located at core and ecotone of the 93 South American ecoregions. Using Linear Mixed Models, we tested whether ecotones have species with more changes from the ancestral diet (higher aTR), have maintained the current diet for a shorter time (lower aST), and have more recent transitions to the current diet (lower aLT) than cores. We found lower aTR, and higher aST and aLT at ecotones than at cores. Although ecotones are more heterogeneous, both environmentally and in relation to selection pressures they exert on organisms, ecotone species change little from the ancestral diet as generalist habits are necessary toward feeding in ephemeral environments. The need to incorporate phylogenetic uncertainty in tip‐based metrics was evident from large uncertainty detected. Our study integrates ecology and evolution by analyzing how fast trait evolution is across space.     

Sex differences in leg dexterity are not present in elite athletes

We studied whether the time-varying forces that control unstable foot–ground interactions provide insight into the neural control of dynamic leg function. Twenty elite (10 F, 26.4 ± 3.5 yrs) and 20 recreational (10 F, 24.8 ± 2.4 yrs) athletes used an isolated leg to maximally compress a slender spring designed to buckle at low forces while seated. The foot forces during the compression at the edge of instability quantify the maximal sensorimotor ability to control dynamic foot–ground interactions. Using the nonlinear analysis technique of attractor reconstruction, we characterized the spatial (interquartile range IQR) and geometric (trajectory length TL, volume V, and sum of edge lengths SE) features of the dynamical behavior of those force time series. ANOVA confirmed the already published effect of sex, and a new effect of athletic ability, respectively, in TL (p = 0.014 and p < 0.001), IQR (p = 0.008 and p < 0.001), V (p = 0.034 and p = 0.002), and SE (p = 0.033 and p < 0.001). Further analysis revealed that, for recreational athletes, females exhibited weaker corrective actions and greater stochasticity than males as per their greater mean values of TL (p = 0.003), IQR (p = 0.018), V (p = 0.017), and SE (p = 0.025). Importantly, sex differences disappeared in elite athletes. These results provide an empirical link between sex, athletic ability, and nonlinear dynamical control. This is a first step in understanding the sensorimotor mechanisms for control of unstable foot–ground interactions. Given that females suffer a greater incidence of non-contact knee ligament injuries, these non-invasive and practical metrics of leg dexterity may be both indicators of athletic ability, and predictors of risk of injury.     

Dendroclimatic potential of dendroanatomy in temperature-sensitive Pinus sylvestris

The most frequently and successfully used tree-ring parameters for the study of temperature variations are ring width and maximum latewood density (MXD). MXD is preferred over ring width due to a more prominent association with temperature. In this study we explore the dendroclimate potential of dendroanatomy based on the first truly well replicated dataset. Twenty-nine mature living Pinus sylvestris trees were sampled in North-eastern Finland at the cool and moist boreal forest zone, close to the latitudinal tree line, where ring width, X-ray MXD as well as the blue intensity counterpart MXBI were compared with dendroanatomical parameters. Maximum radial cell wall thickness as well as anatomical MXD and latewood density appeared to be the most promising parameters for temperature reconstruction. In fact, these parameters compare favorably to MXD derived from X-ray techniques as well as MXBI, in terms of shared variation and temperature correlations across frequencies and over time. The reasons for these results are thought to be the unprecedentedly high measurement resolution of the anatomical technique, which provide the optimal resolution – the cell – whereas X-ray techniques have a slightly lower resolution and BI techniques even lower. While the results of this study are encouraging, further tests on longer and multigenerational chronologies are required to more generally and fully assess the dendroclimate potential of anatomical parameters.     

Application of Preserved Human Amniotic Membrane for Corneal Surface Reconstruction

Objective: To evaluate the efficacy of preserved human amniotic membrane transplantation for reconstruction of the corneal surface diseases. Methods: Preserved human amniotic membrane transplantations were performed in 84 eyes of 78 patients for corneal surface reconstruction. The indications were limbal stem cell deficiency from Steven–Johnson syndrome, chemical burn and herpes keratitis (27 eyes), bullous keratopathy (26 eyes), persistent epithelial defect and dellen (17 eyes), band keratopathy (11 eyes), preparing for prosthesis (1 eye), corneal ulcer (1 eye) and acute chemical burn (1 eye). Results: Success was noted in 83.3% (70/84) eyes, partial success in 13.1% (11/84) eyes, and failure in 3.6% (3/84) eyes for an average follow-up of 10.5 months (3 – 29 months). No patient developed major immediate post-operative complications. Conclusion: Amniotic membrane transplantation can reduce inflammation, promote corneal epithelial healing, and decrease irritation in corneal surface problems.     

Evidence for an interaction between the SH3 domain and the N-terminal extension of the essential light chain in class II myosins

The function of the src-homology 3 (SH3) domain in class II myosins, a distinct beta-barrel structure, remains unknown. Here, we provide evidence, using electron cryomicroscopy, in conjunction with light-scattering, fluorescence and kinetic analyses, that the SH3 domain facilitates the binding of the N-terminal extension of the essential light chain isoform (ELC-1) to actin. The 41 residue extension contains four conserved lysine residues followed by a repeating sequence of seven Pro/Ala residues. It is widely believed that the highly charged region interacts with actin, while the Pro/Ala-rich sequence forms a rigid tether that bridges the approximately 9 nm distance between the myosin lever arm and the thin filament. In order to localize the N terminus of ELC in the actomyosin complex, an engineered Cys was reacted with undecagold-maleimide, and the labeled ELC was exchanged into myosin subfragment-1 (S1). Electron cryomicroscopy of S1-bound actin filaments, together with computer-based docking of the skeletal S1 crystal structure into 3D reconstructions, showed a well-defined peak for the gold cluster near the SH3 domain. Given that SH3 domains are known to bind proline-rich ligands, we suggest that the N-terminal extension of ELC interacts with actin and modulates myosin kinetics by binding to the SH3 domain during the ATPase cycle.     

Reconstructing pre-impact vegetation cover in modified landscapes using environmental modelling, historical surveys and remnant vegetation data: a case study in the Fleurieu Peninsula, South Australia

Aim To investigate the application of environmental modelling to reconstructive mapping of pre‐impact vegetation using historical survey records and remnant vegetation data. Location The higher elevation regions of the Fleurieu Peninsula region in South Australia were selected as a case study. The Fleurieu Peninsula is an area typical of many agricultural regions in temperate Australia that have undergone massive environmental transformation since European settlement. Around 9% of the present land cover is remnant vegetation and historical survey records from the ad 1880s exist. It is a region with strong gradients in climate and topography. Methods Records of pre‐impact vegetation distribution made in surveyors’ field notebooks were transcribed into a geographical information system and the spatial and classificatory accuracy of these records was assessed. Maps of remnant vegetation distribution were obtained. Analysis was undertaken to quantify the environmental domains of historical survey record and remnant vegetation data to selected meso‐scaled climatic parameters and topo‐scaled terrain‐related indices at a 20 m resolution. An exploratory analytical procedure was used to quantify the probability of occurrence of vegetation types in environmental domains. Probability models spatially extended to geographical space produce maps of the probability of occurrence of vegetation types. Individual probability maps were combined to produce a pre‐impact vegetation map of the region. Results Surveyors’ field notebook records provide reliable information that is accurately locatable to levels of resolution such that the vegetation data can be spatially correlated with environmental variables generated on 20 m resolution environmental data sets. Historical survey records of vegetation were weakly correlated with the topo‐scaled environmental variables but were correlated with meso‐scaled climate. Remnant vegetation records similarly not only correlated to climate but also displayed stronger relationships with the topo‐scaled environmental variables, particularly slope. Main conclusions A major conclusion of this study is that multiple sources of evidence are required to reconstruct past vegetation patterns in heavily transformed region. Neither the remnant vegetation data nor historical survey records provided adequate data sets on their own to reconstruct the pre‐impact vegetation of the Fleurieu Peninsula. Multiple sources of evidence provide the only means of assessing the environmental and historical representativeness of data sets. The spatial distribution of historical survey records was more environmentally representative than remnant vegetation data, which reflect biases due to land clearance. Historical survey records were also shown to be classificatory and spatially accurate, thus are suitable for quantitative spatial analyses. Analysis of different spatial vegetation data sets in an environmental modelling framework provided a rigorous means of assessing and comparing respective data sets as well as mapping their predicted distributions based on quantitative correlations. The method could be usefully applied to other regions where predictions of pre‐impact vegetation cover are required.