Miracle-dz/UniFAR-FTUs huggingface dataset:
Factors potentially preventing trophic cascades: Food quality, invertebrate predation, and their interaction

Recent laboratory work on food quality constraints on zooplankton growth and reproduction, as well as several examples of weak effects of food‐web manipulations on lower trophic levels in lakes with phosphorus‐deficient phytoplankton, suggests that food quality effects may have currently unappreciated effects on zooplankton success and food‐web interactions under field conditions. We experimentally manipulated two factors that we anticipated might play a role in suppressing Daphnia in P‐limited lakes—the quality of phytoplankton food and the presence of the invertebrate predator Chaoborus punctipennis. We used a two‐factor design, manipulating food source and presence of Chaoborus, and measured growth rate, survivorship, and fecundity of Daphnia rosea neonates incubated at fixed food levels in flow‐through growth chambers. D. rosea grew significantly faster and was significantly more fecund when fed seston from a high‐food quality lake (Lake 979) relative to a treatment fed seston from a low‐food quality lake (Lake 110). Chaoborus reduced survivorship of D. rosea but the food source–predator interaction term was not significant, indicating that invertebrate predation and phytoplankton food quality did not influence Daphnia populations synergistically in this experiment. A second experiment was conducted to determine if variation in Daphnia growth rate and fecundity when fed food of varying quality was caused by a change in feeding rate. Daphnia feeding rate increased with improved food quality, suggesting that Daphnia responds to increases in food quality, at least in part, by increasing feeding rate. We conclude that food quality can strongly affect Daphnia feeding, growth, and reproduction, thereby constraining food‐web dynamics in nutrient‐deficient lakes.
A new positive/negative selectable marker, puΔtk, for use in embryonic stem cells

Summary: A novel positive/negative selection cassette, puΔtk, was generated. puΔtk is a bifunctional fusion protein between puromycin N‐acetyltransferase (Puro) and a truncated version of herpes simplex virus type 1 thymidine kinase (ΔTk). Murine embryonic stem (ES) cells transfected with puΔtk become resistant to puromycin and sensitive to 1‐(‐2‐deoxy‐2‐fluoro‐1‐β‐D‐arabino‐furanosyl)‐5‐iodouracil (FIAU). Unlike other HSV1 tk transgenes, puΔtk is readily transmitted through the male germ line. Thus puΔtk is a convenient positive/negative selectable marker that can be widely used in many ES cell applications. genesis 28:31–35, 2000. © 2000 Wiley‐Liss, Inc.
Carbon Metabolism Related to Nitrogen Fixation in Soybean Root Nodules

Specific activities of several enzymes involved in the carbon metabolism were compared between roots and nodules of soybean, or between the free-living bacteria, Rhizobium japonicum, and the bacteroids isolated from soybean nodules. Alcohol dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, and phosphoenolpyruvate carboxylase showed higher activities in the nodules than in the roots. Alcohol dehydrogenase and phosphoenolpyruvate carboxylase were localized mostly in the host plant cells of the nodules. Activities of aldehyde dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, and malate dehydrogenase in the bacteroids were higher than those in the free-living bacteria. The sucrose stimulated-acetylene reduction of detached soybean nodules was inhibited by inhibitors of glycolysis, but not by those of the tricarboxylic acid cycle. The respective specific inhibitor of alcohol dehydrogenase, phosphoenolpyruvate carboxylase, and aldehyde dehydrogenase also depressed the acetylene reducing activity o.
Grazing rates of bacterivorous protists inhabiting diverse marine planktonic microenvironments

Bacterivory on aggregates and bulk seawater by three nanoflagellates and a microciliate was investigated. A new approach to measure bacterivory on the attached bacterial community is proposed. Macroaggregates containing attached fluorescently labeled bacteria (FLB) were obtained by adding labeled planktonic bacteria to rolling tanks filled with natural seawater, and they were used to measure protistan grazing rates on the bacteria attached to aggregates. Protistan grazing on free‐suspended bacteria was measured according to the monodispersed FLB uptake technique. The four protists showed low grazing rates when feeding on free‐suspended bacteria at the low densities usually found in seawater. Surprisingly, the analyzed protists also showed low grazing rates when feeding on aggregates despite the very high bacterial densities inhabiting them. The analysis of the influence of prey density on bacterial grazing rates suggests that feeding on bacteria attached to aggregates involves a relevant additional effort when compared to feeding on free‐suspended bacteria. The paradox between these results and the very high abundance of protistan communities usually found in aggregates is discussed attending to the view of aggregates as biological reactors. Therefore, marine macroaggregates can be considered as microniches able to support the maintenance of a protistan community without food limitation, as well as to attract protistan colonizers by generating a water layer enriched in organic matter and bacteria.
Studies on the Status of Unburnt Eucalyptus Woodland at Ocean Grove, Victoria. V. The Interactive Effects of Droughting and Shading on Seedlings Under Competition.

Casuarina littoralis seedlings are inherently more drought-resistant than Eucalyptus ovata seedlings over a wide range of environmental conditions. Moderate shade pre-treatment (30% of full daylight) decreased the drought resistance of seedlings of E. ovata, Acacia pycnantha and C. stricta but not that of C. littoralis seedlings. Deep shade pre-treatment (8 % of full daylight) decreased the drought resistance of all species and was associated with decreased rootlshoot ratios. Both shaded and non-shaded C. littoralis seedlings closed stomata at higher relative water contents (about 80% and 88 % respectively) than did E. ovata seedlings (about 36 % and 63 % respectively). Shading decreased the relative water content at which E. ovata closed stomata and reduced the relative decrease in water potential which occurred with unit decreases in relative water content. When E. ovata and C. littoralis seedlings were grown in competition, the larger E. ovata dominated the drought response of plants under both high and low light conditions. E. ovata rapidly depleted moisture supplies thereby subjecting C. littoralis to greater stress and earlier death than it experienced in monoculture. C. littoralis seedlings grown and droughted in competition with E. ovata exhibited smaIIer decreases in water potential per unit decrease in relative water content than seedlings grown in monoculture. The height growth of E. ovata grown in monoculture and in competition with C. littoralis was reduced for at least 10-15 weeks after the wilting treatment, but height growth of C. littoralis was not affected. Eucalypts wilted at higher water potentials (-4.3 MPa) than did C. littoralis seedlings (- 6.3 MPa). It is suggested that the replacement of E. ovata by C. littoralis at Ocean Grove, Vic. may be partly due to the differential effects of shading on the drought resistance of seedlings which become established in the grass sward of canopy gaps.
An exploratory study on seed morphology of Miconia Ruiz & Pavón (Melastomataceae), with taxonomic and ecological implications

SUMMARY The results of an exploratory study on seed morphology of Miconia Ruiz & Pavon (Melastomataceae) are presented. Seeds of 75 species, mainly from north-western South America, including representatives of all 12 sections of Miconia, were examined, 57 by SEM. Miconia shows an appreciable diversity in seed structure. Twelve major seed types are defined and compared with the current sectional division of the genus and with ecological data. The types do not match with the established sections. The defined seed types may well be of importance for phylogenetic classification, because they possibly indicate relationships. In general, variation in seed morphology in Miconia largely overlaps with variation found in the tribe Miconieae as a whole. Implications for seed dispersal and habitat characteristics are given; the importance of secondary dispersal is discussed. A few species probably are ant-dispersed after having been dropped in vertebrate faeces. Some of the seed types form a species group restricted to certain altitudinal belts and to precipitation zones.
Influence of increasing elevation on growth characteristics at timberline

Significant differences in growing-season air and soil temperatures were found with increasing elevation in the upper montane and forest–alpine tundra ecotone. Temperature inversions in topographic depressions were frequent, especially during the growing season. Variability in bud flush timing with elevation was best accounted for by soil temperatures; however, air temperature recorded within a mat conifer also correlated well with bud flush timing. Significant differences in shoot elongation, needle length, and cuticular thickness were found with differences in climate and elevational changes.
The World's Oldest Fossil Threespine Stickleback Fish

Abstract We report the oldest reliably identified and dated specimen of Gasterosteus aculeatus. The specimen was found after several decades in storage, and we used siliceous microfossils to infer its depositional environment, provenance, and age. The specimen came from a 13.0 to 13.3 Ma deposit in the Monterey Formation of California, probably from the Alta Mira Shale of Palos Verdes. Gasterosteus aculeatus is a highly polytypic and polymorphic species complex. Although this specimen exhibits extreme morphology for this complex, it is not distinctly different from modern Threespine Stickleback for measurable traits, and we consider it to be within the G. aculeatus species complex. Its morphology resembles that of modern marine or anadromous stickleback, which is consistent with the paleoecology of the Alta Mira Shale. Its presence in this deposit, however, is more consistent with a cooler ocean temperature inferred from planktonic diatoms than with the warmer temperature inferred from near-shore, benthic mollusk and epipelagic fish assemblages.
STUDIES ON ABSCISSION: THE PHYSIOLOGICAL BASIS OF THE ABSCISSION‐SPEEDING EFFECT OF INTACT LEAVES

IN EARLIER PAPERS -in this series, the dominant role of auxin from a given leaf blade in controlling the normal rate of abscission of that petiole was demonstrated once again and the relation was quantified (Wetmore and Jacobs, 1953); it was further shown that the presence of intact, unfolded leaves resulted in faster abscission of nearby petioles which had been debladed (Rossetter and Jacobs, 1953). In general, the larger the number of intact, unfolded leaves and the closer they were to the debladed petiole, the faster was the abscission of the debladed petiole. The present paper reports experiments designed to elucidate the mechanism by which the presence of leaves speeds abscission of debladed petioles. A search through the literature brought to light no other reports of leaves speeding abscission of nearby organs. However, both auxin and ethylene, when artificially applied, have been reported to have activities such as might explain our observations. Minute amounts of artificially applied ethylene gas have been known for decades to induce rapid abscission of intact leaves (e.g., Doubt, 1917; Zimmerman et al., 1931). More recently, the production of ethylene gas by plant tissues has been demonstrated for a variety of detached and ripening fruits (Biale et al., 1954; review of earlier work in Biale, 1950). Hall (1951, 1952) stated that cotton and rose leaves which had been excised from the parent plants and placed for 4 days with their petioles in water "produced measurable amounts of ethylene. " The "assay," however, was not as specific as the conclusion: it showed that some volatile substance could be collected which would reduce potassium permanganate. By the use of a more specific chemical test, ethylene production by excised leaves of Silybumn has recently been demonstrated (Pratt, 1954). Even before publication of this proof that at least some excised leaves can emit ethylene, Gawadi and Avery (1950) suggested that an "auxin-ethylene" balance might control abscission in the normal, intact plant-an idea taken up by Hall (1952) and Barlow (1952), although at that time there was no evidence that intact leaves produce ethylene or even have an abscission-speeding (and, therefore, ethylene-like) effect on each other. Addicott and Lynch (1951) reported an experi-
Roadside abundance of raptors in the Western Cape Province, South Africa: a three-decade comparison

Roadside counts of raptors in the southwestern and southern Cape during 1997/98 were compared with data from the 1950s and 1960s. Steppe Buzzard Buteo b. vulpinus, Black-shouldered Kite, Elanus caeruleus, and Yellow-billed Kite, Milvus (migrans) parasitus, opportunistic species preferring human-modified habitat, increased 3–22-fold. Steppe Buzzards furthermore increased proportionately from 25–31% to 60% of the observed raptor population in summer. The globally threatened Lesser Kestrel, Falco naumanni, which underwent a large decline during this period, was recorded 2–5 times mare frequently now than 35 years ago. Records of Rock Kestrel, Falco tinnunculus, Lanner Falcon, Falco biarmicus, and Booted Eagle, Hieraaetus pennatus, also increased. The data on most other species were too limited to be conclusive, but the total number of species observed increased from 15 to 20, despite the fact that the total mileage during this study was only about 20% of the mileage travelled on similar surveys in the 1960s. The results indicate that, although raptor abundance in this area has increased during the last three decades, opportunistic generalists have increased while specialists of indigenous habitat have not, or not to the same extent; this is of conservation concern.
DIVERSIDADE GENÉTICA, TOLERÂNCIA AOS FATORES DE ACIDEZ E EFICIÊNCIA SIMBIÓTICA DE RIZÓBIOS PARA CORNICHÃO DE SOLOS DO RIO GRANDE DO SUL

Birdsfoot trefoil is a perennial winter-spring forage legume, highly important in Rio Grande do Sul, in the south of Brazil. It stands out for the ability to survive in relatively acidic and nutrient-poor soils. This study aimed to select birdsfoot trefoil rhizobial strains with tolerance to acidity and aluminum toxicity and efficiency in nitrogen fixation in nutrient-poor soils. Fifty-two isolates of Lotus spp rhizobia from soils of five locations in the state of Rio Grande do Sul were evaluated. The strains were evaluated for genetic diversity and tolerance to pH 4.2 and to aluminum toxicity. Of the acid-tolerant rhizobia, seven were evaluated for symbiotic efficiency in plants grown in pots with non-sterile soil, in a greenhouse experiment. Genetic diversity in the studied rhizobia was high and 16 were tolerant to pH 4.2 and to 50 µM Al in media broth, reaching populations from 107 up to 108 CFU mL-1. The seven rhizobia tested in the greenhouse performed better than the strains recommended for inoculant production, demonstrating the existence of rhizobia tolerant to soil acidity and efficient in nitrogen fixation on birdsfoot trefoil plants in soils of Rio Grande do Sul.
Factors in Interpreting Data Obtained by Diel Sampling of Fish Stomachs

A simple differential equation model describing the level of food in the stomach, incorporating simultaneous ingestion and gastric evacuation, is used to gauge the sensitivity of methods that utilize diel change in food level of the stomach to determine diel feeding activity of fish. Analysis of model behavior under different feeding regimes shows that diel pattern of food level in the stomach is less sensitive to feeding regime than many authors claim.An expression is derived for the magnitude of bias associated with cessation of feeding and continuance of gastric evacuation while fish are retained by the fishing gear. This bias may be reduced by minimizing sampling time and accelerating preservation of captured fish in experiments to determine feeding chronology and daily ration.
Mark–recapture by genetic tagging reveals restricted movements by bush rats (Rattus fuscipes) in a fragmented landscape

We applied genetic tagging (the identification of individuals by genetic markers) as part of a demographic and genetic analysis of a manipulative study of bush rats Rattus fuscipes in a fragmented landscape in south-eastern Australia. Our study comprised bush rat populations from 30 remnant patches embedded within an extensive exotic pine plantation. Genetic tagging was applied at 12 sites where eight or more animals were encountered in the initial census. Out of a total of 701 DNA samples, we determined (by genetic analysis at 11 microsatellite loci) that 588 bush rat individuals were sampled. Genetic tagging proved to be highly effective, with 97% of animals uniquely identified with three loci, and all animals identified by six loci. Mark–recapture distances moved by genetically tagged animals from the control sites and post-perturbation treatment samples were highly restricted, with a mean of 35 m (35.3±4.5, mean±se, max. 280 m, n=109). This mean distance moved appears to be lower than for other comparable studies of the species. Fragmentation and above-average densities of animals may partially explain this result. An analysis of the factors affecting mark–recapture distance indicated that there was a significant effect of trap layout on the maximum movement detected, but no significant difference in mark–recapture distance between the sexes. We have demonstrated that genetic tagging can facilitate traditional capture–mark–recapture studies in bush rats and pave the way for subsequent population genetic analyses that can offer additional insights not available from ecology alone.
Linking geomorphic character, behaviour and condition to fluvial biodiversity: implications for river management

1. The River Styles® framework is a geomorphic approach to the classification of river types, assessment of the physical condition of rivers, and planning of physical rehabilitation. However, the linkages between River Styles and aquatic biodiversity conservation are still only weakly developed. 2. In this study, 41 sites in the Bega River basin in New South Wales, Australia, were classified according to River Style and geomorphic condition, and surveyed for four biological assemblages: diatoms, aquatic and semi-aquatic macrophytes, aquatic macroinvertebrates and fish. 3. Each assemblage differed significantly among River Styles. However, in the case of diatoms and fish, these differences could be accounted for by geographic clustering of sites in the same River Style, and a tendency for River Styles to occupy particular altitudinal zones and sizes of streams. This result was attributed to the overriding influences of water quality on diatoms and of altitude-related variation in water temperature and distance from the ocean on fish. For macrophytes and macroinvertebrates, geomorphic river type appeared to exert a direct influence, probably via variation in physical habitat characteristics. 4. Geomorphic condition, judged as good, moderate or poor by reference to the inferred natural condition of each River Style, was also significantly associated with differences in biological assemblages other than fish. Twice as many taxa appeared to favour sites in good geomorphic condition as favoured sites in poor condition. Many of the taxa associated with sites in poor condition are alien taxa introduced to Australia since European settlement. 5. These findings imply that protection of reaches that are in good geomorphic condition is likely to be critical for the maintenance of indigenous biodiversity, and that rehabilitation of geomorphic condition can assist in the rehabilitation of native riverine biota. Copyright © 2006 John Wiley & Sons, Ltd.
Evolution of overwintering strategies in Eurasian species of the Drosophila obscura species group

Abstract The phylogenetic relationship of Eurasian species of the Drosophila obscura species group remains ambiguous in spite of intensive analyses based on morphology, allozymes and DNA sequences. The present analysis based on sequence data for cytochrome oxidase subunit I (COI) and α-glycerophosphate dehydrogenase ( Gpdh ) suggests that the phylogenetic position of D. alpina is also ambiguous. These ambiguities have been considered to be attributable to rapid phyletic radiation in this group at an early stage of its evolution. Overwintering strategies are diversified among these species D. alpina and D. subsilvestris pass the winter in pupal diapause, D. bifasciata and D. obscura in reproductive diapause, and D. subobscura and D. guanche without entering diapause. This diversity may also suggest rapid radiation at an early phase of adaptations to temperate climates. On the other hand, adult tolerance of cold was closely related to overwintering strategy and distribution D. obscura and D. bifasciata with reproductive diapause were very tolerant D. alpina and D. subsilvestris which pass the winter in pupal diapause were less tolerant D. subobscura having no diapause was moderately tolerant and D. guanche occurring in the Canary Islands was rather susceptible. Tolerance of high temperature at the preimaginal stages seemed to be also associated with overwintering strategy; i.e. lower in the species with pupal diapause than in those with reproductive diapause or without diapause mechanism.
Assessment of crtRB1 Polymorphism Associated with Increased β-Carotene Content in Maize (Zea mays L.) Seeds

Breeding for increasing β-carotene levels in maize (Zea mays L.) kernel aims to address the dietary vitamin A deficiency. Due to 3’TE polymorphism, the crtRB1gene (that encodes β -carotene hydroxylase 1) exists in the three allelic forms, viz., 3’TE allele 1 (termed favorable allele, for it favors higher β-carotene accumulation in kernels), 3’TE allele 2 and 3’TE allele 3 (both termed unfavorable alleles, for they do not favor β-carotene accumulation). Here, we aimed to identify maize lines with favorable allele. First, 3’TE polymorphism assay in 210 inbreds revealed that only “UMI 176” had the favorable allele while the rest had the unfavorable alleles, confirming the previous finding that favorable allele is rare in frequency. Second, β-carotene content analysis in 24 inbreds revealed that it varied from 4.5 to 7.92 (μg/g), 0.23 to 2, and 0.42 to 4.22 for lines with allele 1, 2, and 3 respectively, corroborating the previous findings that the presence of favorable allele correlates with higher β-carotene content. In summary, UMI 176 has the favorable allele and had the highest amount of β-carotene content (7.92 μg/g), indicating that it is a promising donor line that can be utilized in β-carotene biofortification breeding.