Tracking island colonization history and phenotypic shifts in Indian Ocean bulbuls (Hypsipetes: Pycnonotidae)

Molecular phylogenies of island organisms provide useful systems for testing hypotheses of convergent or parallel evolution, since selectively neutral molecular characters are likely to be independent of phenotype, and the existence of similar environments on multiple isolated islands provides numerous opportunities for populations to evolve independently under the same constraints. Here we construct a phylogenetic hypothesis for Hypsipetes bulbuls of the western Indian Ocean, and use this to test hypotheses of colonization pattern and phenotypic change among islands of the region. Mitochondrial sequence data were collected from all extant taxa of the region, combined with sequence data from relevant lineages in Asia. Data are consistent with a single Hypsipetes colonization of the western Indian Ocean from Asia within the last 2.6 Myr. The expansion of Hypsipetes appears to have occurred rapidly, with descendants found across the breadth of its western Indian Ocean range. The data suggest that a more recent expansion of Hypsipetes madagascariensis from Madagascar led to the colonization of Aldabra and a secondary colonization of the Comoros. Groupings of western Indian Ocean Hypsipetes according to phenotypic similarities do not correspond to mtDNA lineages, suggesting that these similarities have evolved by convergence or parallelism. The direction of phenotypic change cannot be inferred with confidence, since the primary expansion occurred rapidly relative to the rate of mtDNA substitution, and the colonization sequence remains uncertain. However, evidence from biogeography and comparison of independent colonization events are consistent with the persistence of a small grey continental bulbul in India and Madagascar, and multiple independent origins of large size and green plumage in insular island populations of the Comoros, Mascarenes and Seychelles. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85 , 271–287.     

Effects of a forest disturbance on shredder production in southern Appalachian headwater streams

• 1 The effects of a forest disturbance were investigated by comparing production of leaf-shredding aquatic insects in three streams draining a mature hardwood forest and three streams draining an 11-year-old, cable-logged clearcut.
• 2 Reference streams contained significantly greater mean annual standing crop of leaf material and significantly more slow-processing leaf material than disturbed streams. Disturbed streams had a significantly higher mean annual standing crop of fast-processing leaf material than the reference streams.
• 3 Leaf-shredding cranefly (Tipula abdominalis), caddisfly (Pycnopsyche gentilis), and stonefly (Tallaperla maria) larvae comprised over 95% of shredder biomass in all streams. Total shredder production was significantly greater (P<0.05) in disturbed versus reference streams, but individual production rates were not significantly different between stream types.
• 4 Pycnopsyche gentilis larvae were present at higher densities and achieved significantly greater annual biomass in disturbed versus references streams, Biomass of P. gentilis was significantly correlated with the standing crop of fast-processing, early successional leaf material in samples, whereas biomass of other shredders was correlated significantly with medium or slow-processing leaf species characteristic of later stages of forest succession.

     

The mixed xylem sap proteome of Fusarium oxysporum-infected tomato plants

Secreted proteins are known to play decisive roles in plant–fungus interactions. To study the molecular details of the interaction between the xylem-colonizing, plant-pathogenic fungus Fusarium oxysporum and tomato, the composition of the xylem sap proteome of infected tomato plants was investigated and compared with that of healthy plants. Two-dimensional gel separation and mass spectrometry yielded peptide masses and peptide sequences of 33 different proteins. Despite the absence of complete genome sequences of either tomato or F. oxysporum , 21 proteins were identified as tomato proteins and seven as fungal proteins. Thirteen of the tomato proteins were specific for infected plants. Sixteen tomato proteins were found in xylem sap for the first time, four of which were identified based on matches to expressed sequences only. Coding sequences for new proteins from F. oxysporum were identified through either direct matching to a database sequence, matching of peptide sequences to genome or expressed sequence tag databases of other Fusarium species, or PCR with degenerate primers on cDNA derived from infected plants followed by screening of a F. oxysporum BAC library. Together, these findings provide an excellent basis for further exploration of the interaction between xylem-colonizing pathogens and their hosts.     

Molecular adaptation within the coat protein-encoding gene of Tunisian almond isolates of Prunus necrotic ringspot virus

The sequence alignments of five Tunisian isolates of Prunus necrotic ringspot virus (PNRSV) were searched for evidence of recombination and diversifying selection. Since failing to account for recombination can elevate the false positive error rate in positive selection inference, a genetic algorithm (GARD) was used first and led to the detection of potential recombination events in the coat protein-encoding gene of that virus. The Recco algorithm confirmed these results by identifying, additionally, the potential recombinants. For neutrality testing and evaluation of nucleotide polymorphism in PNRSV CP gene, Tajima’s D, and Fu and Li’s D and F statistical tests were used. About selection inference, eight algorithms (SLAC, FEL, IFEL, REL, FUBAR, MEME, PARRIS, and GA branch) incorporated in HyPhy package were utilized to assess the selection pressure exerted on the expression of PNRSV capsid. Inferred phylogenies pointed out, in addition to the three classical groups (PE-5, PV-32, and PV-96), the delineation of a fourth cluster having the new proposed designation SW6, and a fifth clade comprising four Tunisian PNRSV isolates which underwent recombination and selective pressure and to which the name Tunisian outgroup was allocated.     

AdTGF-β1223/225气管内注射制备大鼠肺间质纤维化动物模型

目的观察TGF-β1基因过表达诱发大鼠肺间质纤维化动物模型的组织病理学变化.方法成年健康SD大鼠30只,随机分为空白对照组10只,模型组10只和空载体对照组10只,其中对模型组大鼠气管内一次性注射携带TGF-β1基因腺病毒载体(AdTGF-β1 223/225,1×109 pfu,0.4 mL),空白对照组大鼠气管内注射等量的生理盐水,空载体对照组大鼠气管内注射等量的腺病毒空载体.结果一次性肺气管内注射 AdTGF-β1 223/225可造成肺急性炎症和肺间质纤维化,而对照(腺病毒空载体)并不引起相应的变化.结论肺组织局部分泌的细胞因子TGF-β1可以单独诱发肺间质纤维化.     

Is biofuel policy harming biodiversity in Europe?

We assessed the potential impacts of land-use changes resulting from a change in the current biofuel policy on biodiversity in Europe. We evaluated the possible impact of both arable and woody biofuel crops on changes in distribution of 313 species pertaining to different taxonomic groups. Using species-specific information on habitat suitability as well as land use simulations for three different biofuel policy options, we downscaled available species distribution data from the original resolution of 50 to 1 km. The downscaled maps were then applied to analyse potential changes in habitat size and species composition at different spatial levels. Our results indicate that more species might suffer from habitat losses rather than benefit from a doubled biofuel target, while abolishing the biofuel target would mainly have positive effects. However, the possible impacts vary spatially and depend on the biofuel crop choice, with woody crops being less detrimental than arable crops. Our results give an indication for policy and decision makers of what might happen to biodiversity under a changed biofuel policy in the European Union. The presented approach is considered to be innovative as to date no comparable policy impact assessment has been applied to such a large set of key species at the European scale.     

Error in the inference of fire history from grasstrees

Abstract A method for constructing fire histories has recently been proposed for fire‐prone southern Australia based on the pattern of coloured bands in the remnant leaf‐bases on stems of grasstrees (Xanthorrhoea species; Xanthorrhoeaceae). In the absence of alternative high‐resolution techniques extending into the premodern period, this method has been utilized to construct fire histories for forest, woodland and shrubland ecosystems, principally in south‐western Australia. However, the technique has not been validated against known fire histories spanning more than one fire interval. Here we compare fire records from 100 grasstrees with a 30‐year record (1973–2002) of fire data derived from satellite imagery in a region of sandplain shrubland vegetation near Eneabba in south‐western Australia. Fires occurred in eight of the 30 years of the satellite record, with sampled grasstrees burning between zero and four times. The grasstree and satellite records agreed in terms of the overall incidence of fires experienced over the 30‐year period, with the grasstree record matching the satellite record significantly better than chance. However, comparison of the grasstree and satellite records found substantial error in the rate of both false positives and false negatives. Grasstrees failed to identify fire in 83% of fire occurrences identified by the satellite record, down to 53% if an error of ±2 years in the attribution of year of fire was allowed. A similar proportion of grasstree fire incidents were not matched in the satellite record (false positives). The rate of false positives increased with time before present, suggesting a temporal bias in the grasstree record. It is clear that the grasstree record does reflect fire history to a degree, but that it contains at least as many false as true fire records and may tend towards over‐reporting the incidence of fire in the past.