Shade‐tolerance as a predictor of responses to elevated CO2 in trees

Evidence from 10 studies comparing angiosperm trees and 5 studies comparing conifers of differing shade‐tolerance was analysed. The number of intraphyletic comparisons in which the more shade‐tolerant species showed the greater relative increase of biomass in elevated CO₂ was significantly higher than would be expected by chance alone. It is suggested that more shade‐tolerant species are inherently better disposed, in terms of plant architecture and partitioning of biomass and nitrogen, to utilise resources (light, water, nutrients) that are potentially limiting in elevated CO₂ and that these traits are responsible for the interaction between shade‐tolerance and CO₂ concentration. Compared with less shade‐tolerant angiosperm trees, more shade‐tolerant angiosperm species generally have a lower leaf area ratio in ambient CO₂ and show a smaller relative reduction in elevated CO₂. Furthermore, leaf nitrogen content is usually lower in more shade‐tolerant angiosperm species and tends to be more strongly reduced by elevated CO₂ in those species. Within angiosperm trees, more shade‐tolerant species showed a stronger stimulation of net leaf photosynthetic rate in most experiments, but this trend was not significant.     

Climatic and biogeographical associations of southern African dung beetles (Coleoptera: Scarabaeidae s. str.)

Climatic and biogeographical associations of southern African dung beetles (Scarabaeinae, Coprinae) were analysed from a collection amassed between 1971 and 1986. Endemism to Africa south of 15°S was much greater in southwesterly climates (winter rainfall, bimodal spring/autumn rainfall, arid late summer rainfall) than to the north‐east in the moist, mid‐summer rainfall region. Major biogeographical groups centred to the south‐west comprised predominantly southern African endemics, Western/Eastern Cape coast, Karoo, Karoo/Namib, northern Namibia and the south‐western Kalahari. Biogeographical groups centred on the south‐eastern highlands and the subtropical east coast (mid‐summer rainfall) also comprised predominantly southern African endemics. All other major groups centred to the north‐east in the mid‐summer rainfall region comprised predominantly species with widespread tropical biogeographical affiliations, pan‐southern Africa but centred in the east, pan‐mid‐summer rainfall region, eastern mid‐summer rainfall region, tropical east Zimbabwe/central Moçambique, subtropical/tropical game reserves (non‐ruminant dung specialists). There were cross‐climatic differences in taxonomic composition of the fauna. Within the winter rainfall region, percentage species composition of Scarabaeinae was greater whereas that of the coprine tribe, Onthophagini, was lower than within the other three climatic regions. Percentage species richness of most other tribes of Coprinae differed little between most climates but that of Scarabaeinae declined from west to east (Canthonini, Scarabaeini), east to west (Sisyphini) or to either side of the late summer rainfall region (Gymnopleurini).     

Scavenging of superoxide and hydrogen peroxide in blue‐green algae (cyanobacteria)

Blue‐green algae (cyanobacteria) have evolved as the most primitive, oxygenic, plant‐type photosynthetic organisms. Within a single prokaryotic cell, they have uniquely accommodated both oxygenic photosynthesis and aerobic respiration, which are known to produce superoxide and hydrogen peroxide as inevitable byproducts. Two types of superoxide dismutase have been characterized in both N₂‐fixing and non‐N₂‐fixing cyanobacteria, namely cytosolic iron‐containing superoxide dismutase and thylakoid‐bound manganese‐containing superoxide dismutase. No qualitative differences between various cell types (vegetative cells, heterocysts) were found. In contrast to chloroplasts, most of the cyanobacterial species show catalatic activity. From two species the corresponding enzymes have been characterized as typical prokaryotic (bifunctional) catalase‐peroxidases with homologies to cytochrome c peroxidases and ascorbate peroxidases. In addition to catalatic activity, some strains exhibit ascorbate peroxidase activity, but to date there are no reports detailing purification and characterization.
Cyanobacteria were found to contain low intracellular ascorbate concentrations (30‐100 µ M ) and 2‐5 m M glutathione. Both monodehydroascorbate and glutathione reductase activities were detected in most species examined, whereas dehydroascorbate reductase activity was absent. The question as to whether a glutathione‐ascorbate cycle exists in cyanobacteria cannot be answered at present.     

Seedling growth response to added nutrients depends on seed size in three woody genera

1 We tested whether seedlings of small‐seeded species were more reliant on soil nutrients than large‐seeded ones by growing 21 species from three woody genera ( Eucalyptus, Hakea and Banksia ) along a gradient of nutrient availability.
2 At very low nutrient availability, larger seeds produced larger seedlings. This was seen especially among the eucalypts, but the difference was eliminated at optimal soil nutrient levels. Hakea species with large seed mass, and all Banksia species, appeared unable to exploit additional soil nutrients for growth, whatever the level supplied.
3 Larger seeds tended to have proportionately higher contents of N, P and K and, under nutrient‐poor conditions, supplied more of these to their seedlings, although at a diminishing rate.
4 We suggest that large‐seededness could be an adaptation to the high‐light, nutrient‐impoverished habitats in which these species occur by providing the seedling with the mineral nutrients, rather than carbon‐based metabolites, needed for maximizing initial root growth. Reaching reliable moisture before summer (drought avoidance) is an alternative strategy to physiological tolerance of drought.     

Widespread hybridization among species of Indian major carps in hatcheries, but not in the wild

Twenty‐one allozyme loci in samples of wild‐caught and hatchery‐reared Indian major carps from Bangladesh were analysed. Bayesian model‐based clustering analysis revealed the presence of four taxa, corresponding to the three known species along with a fourth unknown taxon present in two hatchery samples. Individual admixture coefficients showed that 24% of all hatchery‐reared fishes were hybrids, whereas a single hybrid was observed in the wild‐caught samples. Only catla Catla catla × rohu Labeo rohita and mrigal Cirrhinus cirrhosus × rohu hybrids were observed, the vast majority of which were F₁ hybrids, though five individuals represented putative backcrosses. Mitochondrial DNA analysis revealed that catla × rohu hybridization primarily involved catla males and rohu females, whereas mrigal × rohu hybrids primarily resulted from rohu males and mrigal females. Despite the high percentage of F₁‐hybrids in hatchery samples, reproductive barriers among species have so far precluded widespread introgression. Continued hybridization may eventually lead to a breakdown of species barriers, thereby compromising the genetic integrity of the species in the wild, and leading to production losses in aquaculture.     

Trophically transmitted parasites in wild Atlantic salmon post‐smolts from Norwegian fjords

The community structure of trophically transmitted intestinal helminths of Atlantic salmon Salmo salar post‐smolts was highly variable among four fjords in Norway. There were no severely pathogenic parasite species. Post‐smolts from the southernmost Trondheimsfjord had a higher diversity of freshwater parasite species compared to the three northern fjords (Tanafjord, Altafjord and Malangen). In contrast, the highest diversity and proportion of marine species was found in the three northern fjords. Post‐smolts were generally more infected with marine parasites in the outer rather than inner parts of all of the fjords. The prevalence of the acanthocephalan Echinorynchus gadi (range: 13–42%) and marine trematodes (range: 14–47%) was higher in post‐smolts in outer zones of the northern fjords than in fish from Trondheimsfjord (0 and 6%, respectively). The within‐fjord variability and north‐south geographical gradient in parasite infection patterns reflected differences in marine feeding of the post‐smolts on potential intermediate hosts such as amphipods ( E. gadi ) and fish larvae (trematodes), which were higher in the northern fjords (range: 27–28 and 67–85%, respectively) than in Trondheimsfjord (5 and 19%, respectively). High intensities of marine parasites suggest that some post‐smolts from northern fjords may have a prolonged fjord‐feeding compared to those from Trondheimsfjord. Parasites of both freshwater and marine origin appear to be suitable as bio‐indicators of feeding and migratory pattern of Atlantic salmon post‐smolts and preadults during their seaward migration.     

A comparative study on carbohydrate reserves and ethanolic fermentation in the roots of two wetland and non‐wetland species after commencement of hypoxia

The problem of availability of storage carbohydrates (fructans and starch) in oxygen‐deficient roots was investigated in wetland species ( Senecio aquaticus Hill., Myosotis palustris [L.] L. Em. Rchb.) and compared with related non‐wetland species ( Senecio jacobaea L., Myosotis arvensis [L.] Hill.) with respect to ethanolic fermentation (PDC activity, ethanol production).
In response to 24 h of hypoxic treatment, the pyruvate decarboxylase (PDC) activity in roots increased 4‐fold in M. arvensis and S. jacobaea , 2‐fold in S. aquaticus and only slightly in M. palustris . The rise in PDC activity was accompanied by an increase in ethanol content in the roots. The increase in ethanolic fermentation in roots of intact plants was associated with a slight increase in fructose and glucose and in a clear rise in sucrose content during the first 24‐48 h after commencement of the hypoxic treatment. Following 24 h of hypoxia, the content of fructans started to increase significantly for the duration of the experiment (9 days) in the four species. Since starch content changed only slightly during this period, the fructan:starch ratio increased under low energy availability. In the roots of flooding‐tolerant Senecio aquaticus , the ratio shifted most clearly from 2:1 in normoxia to 9:1 in hypoxia. For the roots of the two wetland species investigated, the results indicate a stronger accumulation of carbohydrates accompanied by a lower increase in PDC activity under root hypoxia, when compared with the related non‐wetland species respectively.     

Effects of temperature on free‐embryonic diapause in the autumn‐spawning bitterling Acheilognathus rhombeus(Teleostei: Cyprinidae)

In bitterling Acheilognathus rhombeus , developmental arrest always occurred at stage D of the free‐embryonic phase, regardless of incubation temperature. Developmental arrest was terminated only by a cold treatment at 4° C for 60–90 days, initiated 10 days post‐hatching. After the termination of developmental arrest, free‐embryos became larvae c . 6 months after hatching, regardless of the time of initiation and duration of the cold treatment. In hybridization experiments between A. rhombeus and several species of spring‐spawning bitterlings, free‐embryos became free‐swimming larvae within 60 days after hatching in all experiments. Developmental arrest was not observed in any of the hybrids, regardless of parental sex. These results suggest that free‐embryonic diapause in A. rhombeus is not induced by environmental factors, such as cold, but by genetic factors, which are recessive to those in spring‐spawning bitterlings. Free‐embryonic diapause in A. rhombeus appears to be an adaptation to winter, which might have evolved with reproduction in autumn among autumn‐spawning bitterling species. This is the only report of free‐embryonic diapause after hatching in fishes, and only the second example of diapause in fishes, along with annual killifishes (Rivulidae).     

Comparative ecology of two African forest mongooses, Herpestes naso and Atilax paludinosus

During a two‐year period, two mongoose species ( Herpestes (Xenogale) naso and Atilax paludinosus ) were studied in the Dzanga‐Sangha forest of south‐western Central African Republic by live‐trapping, radio‐telemetry, tracking and scat analysis. Clear separation with respect to habitat, activity patterns and food habits was observed. Herpestes naso , previously thought to be rare and known only from a few museum specimens, was the most abundant species in the carnivore community; in total, eleven individuals were trapped. Radio‐collared Herpestes naso spent most of their time in upland forest, but a high degree of range overlap was observed in stream‐side habitat. They were strictly diurnal and the location of their nocturnal resting sites varied from day to day. Atilax paludinosus was restricted to the swamp forest immediately adjacent to streams. A radio‐collared male exhibited a crepuscular activity pattern, and the distribution of day‐beds along the length of its home range was highly clumped. Mean travelling speeds of Atilax exceeded those of Herpestes , most likely because of the near linear shape of its home range and greater distance between borders. The diets of both carnivores were dominated by arthropods, with Atilax consuming more aquatic prey than Herpestes . It is suggested that the higher degree of habitat specificity exhibited by Atilax in the study area compared with other parts of its range was a result of the absence of otters from the smaller tributaries of the Dzanga‐Sangha forest or perhaps to the social dominance of Herpestes naso .     

Effects of supplementary feeding on growth and reproduction of three carnivorous plant species in a subarctic environment

1 The effect of supplementary feeding on growth and reproduction of three carnivorous plants species was investigated over a 6‐year period. Pinguicula alpina , P. villosa and P. vulgaris populations growing at two altitudes in a subarctic environment were fed with fruit flies ( Drosophila melanogaster ).
2 Fed plants increased in size relative to control plants during the first years. Subsequently a stable size difference between feeding levels was established. The weight of the over‐wintering part was higher in fed plants than in control plants.
3 The flowering frequency (i.e. proportion of plants in a population carrying flowers) was also higher in the fed plants. The proportion of flowering plants increased in the feeding treatment compared to control plants during more‐or‐less the whole experimental feeding period (5–6 years). Seed production also increased slowly in response to feeding.
4 No feeding effect on nitrogen and phosphorus concentrations in seeds and over‐wintering parts was found.
5 In most characteristics the high‐altitude populations were less responsive than populations growing at low altitude. In the high‐altitude population reproduction failed repeatedly, suggesting that seed output may be more dependent on abiotic factors than on resource availability in cold environments.
6 Pinguicula villosa and P. vulgaris used the new resources the same summer for increased leaf rosette growth and current reproduction, showing these species to be income breeders, while the third species ( P. alpina ) allocated a larger proportion to storage and future reproduction, characteristic of a capital breeder.     

A 38‐year study of relations between weather and vegetation dynamics in road verges near Bibury, Gloucestershire

1 The Bibury long‐term data set contains information on annual fluctuations in the abundance of over 100 grasses and forbs in roadside verge vegetation over the period from 1958 to the present. Monitoring has been carried out every July by the same individual. The data set represents a unique long‐term record of the dynamics of a complete plant community.
2 Records for the most abundant taxa (including bare ground and litter) were used to determine the effect of climate variability on the year‐to‐year performance of the selected species. Residuals about the long‐term mean log biomass of each species (de‐trended where the species showed a significant increase or decrease in abundance over time) were correlated against indices of interannual climate variability. Plant and weather records were compared over 3‐month seasonal periods (March–May, June–August, September–November, December–February) or 6‐month seasonal periods (March–August, September–February), with time lags of 0, 1 and 2 years.
3 Principal components analysis (PCA) was used to formulate annual weather indices, using either conventional weather variables (temperature, rainfall and sunshine) or the Lamb catalogue of daily weather types.
4 Between 5% and 70% more correlations were observed than might be expected to occur by chance, depending on the season and the PCA index, indicating markedly non‐random plant–weather relationships. Total vegetation production was positively correlated with minimum spring temperature. The distribution of correlations was generally evenly distributed across the three lag periods.
5 In general, those species favoured by environmental stress or disturbance were promoted following warm dry springs and summers, whereas those favoured by more productive conditions were promoted following a wet growing season.     

The use of egg chorion glycoprotein of Epinephelus malabaricus for egg identification

An immuno‐probe against a glycoprotein in the egg chorion was developed for egg identification. The 97 kD glycoprotein in the chorion of unfertilized eggs of Epinephelus malabaricus was isolated and separated by SDS‐PAGE as an antigen to induce antibody from rabbit. The reactivity of the antibody as the immuno‐probe to E. malabaricus eggs was significantly positive, and was specific in that it did not react with the eggs of other fish species. The immuno‐probe should be useful in identifying the eggs of E. malabaricus among mixed egg populations.     

Triplophysa rosa sp. nov.: a new blind loach from China

A new blind loach of Triplophysa Rendahl 1933 was collected from a subterranean pool in a cave at Wulong County, Chongqing City, China, in November 2002. The new species, named Triplophysa rosa sp. nov., can be distinguished from its congeners by the following unique characters: eyes vestigial; 9 branched dorsal‐fin rays; 12 branched pectoral‐fin rays; 7 branched pelvic‐fin rays; 6 branched anal‐fin rays; 7 + 7 branched caudal‐fin rays; distal margin of dorsal‐fin concave; tip of pelvic‐fin surpasses vertical level of anus; caudal‐fin deeply forked; whole body scaleless and colourless.     

Isolation of c‐myc genes from goldfish and their tissue specific expression

One novel cellular myc gene (c‐ myc ), GM 1, was isolated from a tetraploid cyprinid, the goldfish Carassius auratus . GM 1 consisted of one non‐coding exon and two coding exons, presumably encoding a protein of 390 amino acid (aa) residues. The aa identity between GM 1 and GM 2, another c‐ myc previously isolated from this species, was 88·8%. Quantitative RT‐PCR analysis revealed that GM 1 was specifically expressed in liver and GM 2 in ovary.     

Composition and antagonistic activity of the indigenous intestinal microbiota of Prochilodus argenteus Agassiz

The composition and antibacterial properties of indigenous intestinal microbiota from Prochilodus argenteus were studied during reproductive (alimentary restriction) and non‐reproductive (normal feeding) periods. Dilutions of intestinal contents from 21 specimens of P. argenteus captured from São Francisco Basin, Minas Gerais State, Brazil, were used for enumeration, isolation, identification and determination of in vitro antibacterial properties of predominant components of the intestinal microbial ecosystem. Predominant species recovered for both periods were: Aeromonas hydrophila , Plesiomonas shigelloides, Lactococcus lactis and an unidentified Gram‐positive rod for facultative anaerobes and Bacteroides stercoris/eggerthii and Fusobacterium mortiferum for obligate anaerobes. Gram‐positive components of this microbiota showed high antagonistic activity against gram‐negative species. Coagulase‐negative Staphylococcus sp., Enterococcus durans, Enterococcus faecium and the unidentified gram‐positive rod had wider range of antagonism properties. The indigenous intestinal microbiota of P. argenteus was quite similar to that of other fishes and the reproductive and alimentary status has few influences on its composition.     

Peroxisomal manganese superoxide dismutase: Purification and properties of the isozyme from pea leaves

The peroxisomal manganese superoxide dismutase (perMn‐SOD; EC 1.15.1.1) was purified to homogeneity for the first time from peroxisomes of pea ( Pisum sativum L.) leaves. Peroxisomes were isolated from pea leaves by sucrose density‐gradient centrifugation, and then perMn‐SOD was purified from these organelles by two purification steps involving anion‐exchange and gel‐filtration fast protein liquid chromatography. Pure peroxisomal Mn‐SOD had a specific activity of 2 880 units per mg protein and was purified 3 000‐fold, with a yield of about 7 µg enzyme per kg pea leaves. The relative molecular mass determined for perMn‐SOD was 92 000, and it was composed of four equal subunits of 27 kDa. Ultraviolet and visible absorption spectra of the enzyme showed two absorption maxima at 278 and 483 nm, respectively, and two shoulders at 290 and 542 nm. By isoelectric focusing (pH 5‐7), an isoelectric point of 5.53 was determined for perMn‐SOD. In immunoblot assays, purified Mn‐SOD was recognized by a polyclonal antibody against mitochondrial Mn‐SOD (mitMn‐SOD) from pea leaves. The amino acid sequence of the N‐terminal region of the purified peroxisomal enzyme was determined. A 100% identity was found with the mitMn‐SOD from pea leaves, and high identities were also found with Mn‐SODs from other plant species.     

Allometric growth and sperm competition in fishes

The allometric relationship between body mass and gonad mass in males of 23 fish species from 11 families was examined. There was no evidence of a single allometry for all fishes. A cross species analysis suggested a scaling coefficient of 1·04, which was significantly different from a previous study that reported a scaling coefficient of 0·904. A within species analysis generated scaling coefficients from 0·68 to 3·90. Furthermore, for those species characterized by alternative mating tactics, there was no correlation between the scaling coefficients of bourgeois‐type males and parasitic‐type males. These results are discussed in the context of the gonado‐somatic index and its use in testing sperm competition theory.     

Spatial patterns of the biological traits of freshwater fish communities in south‐west France

Spatial patterns in the combinations of biological traits of fish communities were studied in the Garonne River system (57 000 km², south‐west France). Fish species assemblages were recorded at 554 sampling sites, and the biological traits of species were described using a fuzzy‐coding method. A co‐inertia analysis of species distributions and biological traits identified some spatial patterns of species trait combinations. Fish species richness progressively increased from up‐ to downstream sections, and the longitudinal patterns of fish assemblages partitioned the river into clear biogeographic areas, such as the brown trout Salmo trutta (headwater streams), the grayling Thymallus thymallus , the barbel Barbus barbus and the bream Abramis brama zones (most downstream sections), which fitted with Huet's well‐known zonation for western European rivers. Only a few biological traits, chiefly related to life‐history attributes, significantly influenced the observed fish distributions. Fecundity, potential size, maximum age and reproductive factor increased from headwater to plain reaches. As a theoretical framework for assessing and predicting the functional organization of stream fish communities, spatial variations in species traits can be related to habitat conditions, thus providing explicit spatial schemes that may be useful to the design of both scientific studies and river management.     

Introgressive hybridization between Dolly Varden Salvelinus malma and white‐spotted charr Salvelinus leucomaenis on Hokkaido Island, Japan

Intra‐ and interspecific phylogenetic analysis of Dolly Varden Salvelinus malma and white‐spotted charr Salvelinus leucomaenis throughout Hokkaido Island was conducted using nucleotide sequences of the mitochondrial DNA control region and three nuclear DNA markers [ribosomal DNA (ITS‐1), microsatellite ( u ‐85), SINE ( Fok ‐223)]. A total of 19 mtDNA haplotypes from 271 individuals of Dolly Varden, nine haplotypes from 134 white‐spotted charr were defined, and identified two well‐supported monophyletic clades for each species. Two haplotypes of Dolly Varden, however, were clustered together in the white‐spotted charr clade. Those haplotypes were found only from several rivers in the Shiretoko Peninsula, and a neighbouring river of that region. Analyses of ribosomal DNA and Fok ‐223 loci revealed that both species are characterized by having completely species‐specific diagnostic sequence and fragment patterns. Dolly Varden of the Shiretoko populations are typically allopatric in distribution where white‐spotted charr do not currently occur. In addition, incongruence in genetic relationships between mtDNA and nuclear DNA markers give strong evidence of historical mtDNA introgression between Dolly Varden and white‐spotted charr. Some white‐spotted charr diagnostic alleles in a nuclear microsatellite locus ( u ‐85) were found in some Shiretoko Dolly Varden populations, suggesting that introgressive hybridization might have also occurred in relatively recent contact and potentially ongoing evolutionary event. The present study presents an example of historical hybridization and introgression at the southernmost distribution limits of Dolly Varden.     

Electroantennogram studies of potential oviposition attractants for Toxorhynchites moctezuma and T. amboinensis mosquitoes

Abstract.Ether extracts of water samples taken from tyre sections in the field were shown to be active in electroantennogram studies with female Toxorhynchites moctezuma (Dyar & Knab) and Toxorhynchites amboinensis (Doleschall). In addition, electroantennograms were recorded from both Toxorhynchites species for seven compounds found commonly in water containing decaying leaves and known to be oviposition attractants for other mosquito species. The compounds were 4‐methylcyclohexanol, phenol, indole, 3‐methylindole, m‐ cresol, o‐ cresol and p‐ cresol. The response thresholds for these compounds ranged between 1 × 10^–4μg and 1 μg for female antennae (100 μg for male antennae). These results provide a basis for behavioural studies of oviposition attractants for the Toxorhynchites species.