山西省异爪蝗属二新种（直翅目：网翅蝗科）

本文记述在晋南地区采到的异爪蝗属二新种,黑条异爪蝗Euchorthippus nigiliineatus sp.nov.及曲线异爪蝗Eochorthippus sinucarinatus sp.nov.     

Thecamoeba foliovenanda n. sp. (Amoebozoa,Discosea, Thecamoebida) – One more case of sibling species among amoebae of the genus Thecamoeba

Until recently it seemed that amoebae of the genus Thecamoeba can be reliably identified using light-microscopic characters, like the size and shape of the cell, a characteristic pattern of folds and ridges and structure of the nucleus. However, recent molecular studies show the presence of sibling species that can be reliably distinguished based on the gene sequence data only. Here we describe a new terrestrial species, Thecamoeba foliovenanda n. sp. This species is almost identical with Thecamoeba similis in light-microscopy, which has minor differences in the ultrastructure but considerable differences in the SSU rRNA gene sequence. We investigated the light-microscopic data, as well as transmission electron-microscopic images and videorecords on the type strain of T. similis 1583/8 and performed its comparison with the new species. This study further supports the conclusion that species of the genus Thecamoeba nowadays require gene sequencing for reliable identification and species distinction.     

Pathogenic Allodiploid Hybrids of Aspergillus Fungi

1. Download : Download high-res image (256KB)
2. Download : Download full-size image

     

EPR properties of mixed-valent μ-oxo and μ-hydroxo dinuclear iron complexes produced by radiolytic reduction at 77 K

 Radiolytic reduction at 77 K of oxo-/hydroxo-bridged dinuclear iron(III) complexes in frozen solutions forms kinetically stabilized, mixed-valent species in high yields that model the mixed-valent sites of non-heme, diiron proteins. The mixed-valent species trapped at 77 K retain ligation geometry similar to the initial diferric clusters. The shapes of the mixed-valent EPR signals depend strongly on the bridging ligands. Spectra of the Fe(II)OFe(III) species reveal an S=1/2 ground state with small g-anisotropy as characterized by the uniaxial component (g _z –g _av /2<0.03) observable at temperatures as high as ∼100 K. In contrast, hydroxo-bridged mixed-valent species are characterized by large g-anisotropy (g _z –g _av /2>0.03) and are observable only below 30 K. Annealing at higher temperatures causes structural relaxation and changes in the EPR characteristics. EPR spectral properties allow the oxo- and hydroxo-bridged, mixed-valent diiron centers to be distinguished from each other and can help characterize the structure of mixed-valent centers in proteins. Received: 27 June 1998 / Accepted: 25 February 1999     

Phylogenetic and phenotypic structure among Banksia communities in south‐western Australia

Aim Phylogenetic and phenotypic patterns among coexisting banksias (Banksia, Proteaceae) in the infertile, fire‐prone landscapes of south‐western Australia were examined for evidence of community structuring. It was expected that closely related species would be spatially clustered (underdispersed) as a consequence of widespread recent speciation, strong edaphic fidelity and low dispersability. We also expected that edaphic filtering would result in phenotypic clustering of traits related to habitat specialization and that competitive exclusion among closely related species with similar regeneration biology and growth form would result in phenotypic overdispersion of these latter traits. Location Southwest Australian Floristic Region (SWAFR). Methods Based on published data for coexistence (richness and frequency) of Banksia species at 40 sites in the three floristic provinces, phylogenetic, soil type and morphological mean pairwise distance and mean nearest taxon distance were calculated for each site and compared with null communities. Patterns of co‐occurrence were examined at the local and subregional (provincial) scales. Results Of the 40 sites assessed, 21–30 displayed phylogenetic clustering of Banksia species (5–11 significantly) such that, overall, co‐occurring taxa were more closely related than expected by chance. Banksias in the Transitional Rainfall and Southeast Coastal Provinces were more likely to display phylogenetic clustering than in the High Rainfall Province. A significant trend for phylogenetic clustering associated with edaphic specialization (27–30 sites) was observed, as well as a significant trend for phenotypic overdispersion associated with growth form (25–28 sites). Results for regeneration biology depended on the metric used. Main conclusions We demonstrate spatial clustering of closely related banksias at the local and provincial scales, consistent with their restricted distribution (recent widespread speciation, patchy habitat availability and limited dispersability) in this geologically old and stable region. The clustering of closely related species may also be a consequence of habitat filtering linked to edaphic fidelity in the SWAFR flora, while overdispersion in growth form suggests that functional divergence favours coexistence in Banksia communities.     

The recolonization of the Krakatau islands by termites (Isoptera), and their biogeographical origins

The termite assemblages of the Krakatau islands and five sites in Sumatra and Java were investigated, using a standardized transect sampling method. Five species were found on the Krakatau islands that have not been collected there before. The total number of termites recorded on the islands since the 1883 volcanic eruption is now twelve species, all of which are wood feeders. No termites nesting in or feeding on the soil were found on the Krakataus, suggesting that rafting in wood is the primary method by which the termites recolonized the islands.     

Amazonian biodiversity: assessing conservation priorities with taxonomic data

Data from 3991 records of museum collections representing 421 species of plants, arthropods, amphibians, fish, and primates were analyzed with GIS to identify areas of high species diversity and endemism in Amazonia. Of the 472 1 × 1° grid cells in Amazonia, only nine cells are included in the highest species diversity category (43–67 total species) and nine in the highest endemic species diversity category (4–13 endemic species). Over one quarter of the grid cells have no museum records of any of the organisms in our study. Little correspondence exists between the centers of species diversity identified by our collections-based data and those areas recommended for conservation in an earlier qualitative study of Amazonian biodiversity. Museum collections can play a vital role in identifying species-rich areas for potential conservation in Amazonia, but a concerted and structured effort to increase the number and distribution of collections is needed to take maximum advantage of the information they contain.     

The fifteenth- and twentieth-century colonization of the Basin of Mexico by the Great-tailed Grackle (Quiscalus mexicanus)

Historical evidence indicates that Great‐tailed Grackles colonized the Basin of Mexico from the Gulf Coast lowlands in the fifteenth century. They were probably assisted by an intentional introduction, but colonization succeeded because of anthropogenic habitat alterations over the previous two centuries. During the Colonial period, grackles withdrew from the Basin, only to recolonize it in recent decades. This withdrawal was also due probably to changes in land use, including drainage of much of the water from the Basin's lakes.     

A relict population of Fagus grandifolia var. mexicana at the Acatlan Volcano, Mexico: structure, litterfall, phenology and dendroecology

Aim Fagus grandifolia var. mexicana (Martinez) Little has an extraordinarily restricted distribution in the Mexican montane cloud forests. Isolated Fagus (beech) populations have been recorded in less than 10 small areas (2–40 ha) in the eastern Sierra Madre at altitudes from 1400 to 2000 m. The objectives were to determine tree and seedling age, forest structure, phenology, litterfall patterns and the relationship between mast and climatic variables. Location We report on three Fagus stands at the Acatlan Volcano, Veracruz, Mexico. Methods Changes in forest cover were determined using aerial photographs. Within each stand, basal area, density and tree species composition were determined in a 0.1‐ha band transect. Additionally, litterfall production was quantified and phenophases were recorded monthly over a 3‐year period, and 60 tree cores were collected to determine age distribution and tree‐ring growth. Results The forest was atypical in several respects. Fagus was the only dominant tree species in the crater stand, although in the rim and at the top of the volcano it was codominant with other tree species. Juveniles occurred only on the rim, but there was a seedling bank in the crater. Although forest cover in the area increased between 1968 and 1993, the Fagus stands did not change in size. Leaf production peaked in March and April, and leaf fall occurred from October through February. Litterfall production was the highest in November. During mast years, flowering started in February and between mast events there were no flowers or fruits. Minimum temperatures were highly correlated with Fagus litterfall and leaf fall. Seedlings ranged in age from 2 to 18 years and were 13–60 cm tall. Tree cores ranged from 76 to 120 years, but trees were older than the core samples. Main conclusions Although beech is considered a gap regeneration species that reaches the canopy after alternating periods of release and suppression, the trees in the crater were released when less than 1.5 m tall and have suffered few periods of suppression since. The results indicate that the crater stand was established after a severe disturbance destroyed the existing forest. We conclude that the relict beech population should be able to maintain itself, if not severely disturbed by humans or by climatic changes related to global warming.