Coccoliths as paleoclimatic indicators of pleistocene glaciation

Selected species of Coccolithophoridae from recent sediments and mid-Wisconsin glacial sediments of the North Atlantic were examined in an attempt to determine cooling effects. All species showed a definite shift southward during the glacial period. The average shift in this planktonic population was 15 degrees of latitude, with the greatest change in the eastern Atlantic. A paleoisotherm map can be drawn on the basis of the temperature boundaries of coccolithophorids. The species boundaries indicate a possible shift in position of the subtropical gyral to a glacial position roughly parallel to the 33-degree line of latitude.     

Effects of legume intercrops on soil-borne pests, biomass, nutrients and soil water in banana

Banana (Musa AAA) and plantain (Musa AAB) are important dietary staples for over 70 million people in sub-Saharan Africa. Banana weevil (Cosmopolites sordidus) and nematodes (Radopholus similis, Helicotylenchus multicinctus) are often the largest constraints to production. Leguminous crops in the genera Canavalia, Mucuna and Tephrosia have been reported as having repellent or insecticidal properties. We assessed: weevil and nematode populations and damage; banana growth and development; soil and foliar nutrient concentrations; and soil moisture status in banana intercropped with three legumes (Canavalia ensiformis, Mucuna pruriens and Tephrosia vogelii). The research took place at Kawanda, Uganda, on a field site infested with weevils and nematodes. The legume intercrops did not affect weevil populations or damage. The legumes also provided no benefit in terms of nematode control; in fact, banana root necrosis was higher in the T. vogelii intercrop than in the banana monoculture. Banana fruit yield was not adversely affected by the legume intercrops. The low yield noted across treatments was attributed to the high level of damage by the weevils and the nematodes. Significantly more NO₃-N accumulated from 0- to 0.3-m depth in the M. pruriens intercrop than in the other treatments. There was no treatment difference in soil moisture. In summary, there was no significant advantage in banana production associated with the legume intercrops. However, the lack of a significant difference in banana fruit production between the monoculture and the intercrops suggests that land use efficiency may be increased by incorporating food and or/fodder legumes into the banana cropping system.     

Characterisation of Erianthus sect. Ripidium and Saccharum germplasm (Andropogoneae - Saccharinae) using RFLP markers

A collection of 65 Erianthus Michx. sect. Ripidium Henrard accessions (representing seven accepted species) and 14 Saccharum L. representatives (S. officinarum L. and S. spontaneum L.) were studied by RFLP analysis using 14 dispersed nuclear single-copy probes from maize. An intergeneric distance (1–F) of 0.748 was revealed between Erianthus and Saccharum. Within the Erianthus collection, the greatest distances were found between E. elephantinus Hook f. or E. ravennae (L.) P. Beauv. (the two 2n=20 species), and the rest of the Erianthus collection. The smallest distances were found amongst the E. arundinaceus (Retz.) Jeswiet clones collected in Indonesia ((1–F)=0.005). In addition, a partition based on the geographical origin and consistent with the chromosome numbers, ie E. arundinaceus from Indonesia versus E. arundinaceus and E. procerus from India, was revealed. E. bengalense was intermediate. The study of the Saccharum individuals confirmed the greater variability of S. spontaneum compared to the so called noble cane, S. officinarum. The 2n=80 S. spontaneum genotypes were shown to be closely related to S. officinarum. The implication of these results on the involvement of S. spontaneum and Erianthus sect. Ripidium in the origin of S. officinarum is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cattle temperament: persistence of assessments and associations with productivity, efficiency, carcass and meat quality traits

Relationships between temperament and a range of performance, carcass, and meat quality traits in young cattle were studied in 2 experiments conducted in New South Wales (NSW) and Western Australia (WA), Australia. In both experiments, growth rates of cattle were assessed during backgrounding on pasture and grain finishing in a feedlot. Carcass and objective meat quality characteristics were measured after slaughter. Feed intake and efficiency during grain finishing were also determined in NSW. Brahman (n = 82 steers and 82 heifers) and Angus (n = 25 steers and 24 heifers) cattle were used in the NSW experiment. In NSW, temperament was assessed by measuring flight speed [FS, m/s on exit from the chute (crush)] on 14 occasions, and by assessing agitation score during confinement in the crush (CS; 1 = calm to 5 = highly agitated) on 17 occasions over the course of the experiment. Brahman (n = 173) and Angus (n = 20) steers were used in the WA experiment. In WA, temperament was assessed by measuring FS on 2 occasions during backgrounding and on 2 occasions during grain feeding. At both sites, a hormonal growth promotant (Revalor-H, Virbac, Milperra, New South Wales, Australia) was applied to one-half of the cattle at feedlot entry, and the Brahman cattle were polymorphic for 2 calpain-system markers for beef tenderness. Temperament was not related (most P > 0.05) to tenderness gene marker status in Brahman cattle and was not (all P > 0.26) modified by the growth promotant treatment in either breed. The Brahman cattle had greater individual variation in, and greater correlations within and between, repeated assessments of FS and CS than did the Angus cattle. Correlations for repeated measures of FS were greater than for repeated assessments of CS, and the strength of correlations for both declined over time. Average FS or CS for each experiment and location (NSW or WA × backgrounding or finishing) were more highly correlated than individual measurements, indicating that the average values were a more reliable assessment of cattle temperament than any single measure. In Brahman cattle, increased average FS and CS were associated with significant (P < 0.05) reductions in backgrounding and feedlot growth rates, feed intake and time spent eating, carcass weight, and objective measures of meat quality. In Angus cattle, the associations between temperament and growth rates, feed intake, and carcass traits were weaker than in Brahmans, although the strength of relationships with meat quality were similar.     

Is landscape context important for riparian conservation? Birds in grassy woodland

An important challenge for riparian management is to determine the extent to which landscape context influences the faunal assemblages of riparian habitats. We examined this challenge in the variegated landscapes of southeastern Queensland, Australia where riparian vegetation is surrounded by both extensive grazing and intensive cropping. We investigated whether riparian habitats adjacent to different landuses support similar bird assemblages. Three types of riparian habitat condition were sampled (uncleared ungrazed; uncleared grazed; cleared grazed) in four different land-use contexts (ungrazed woodland; grazed woodland; native pasture; crop) although only six of the 12 possible treatment combinations were available. Eighty percent of bird species responded significantly to changes in both riparian habitat condition and landscape context, while fewer than 50% of species were significantly influenced by landscape context alone. The influence of landscape context on the bird assemblage increased as the surrounding land use became more intensive (e.g., woodland to native pasture to crop). Riparian zones have been shown to have consistently high biodiversity values relative to their extent. These findings suggest it is not enough to conserve riparian habitats alone, conservation and restoration plans must also take into consideration landscape context, particularly when that context is intensively used land.     

Polymers: synthesis and characterization of extremely high-molecular-weight polystyrene

Polystyrenes with molecular weights up to 44 x 10(6) grams per mole have been characterized by light-scattering and equilibrium ultracentrifugation methods. The Mark-Houwink equation, which relates the molecular weight and the intrinsic viscosity of flexible polymers, can be used only if the measurements are made in a theta solvent at the theta temperature.     

Using open-access taxonomic and spatial information to create a comprehensive database for the study of Mammalian and avian livestock and pet infections

What are all the species of pathogen that affect our livestock? As 6 out of every 10 human pathogens came from animals, with a good number from livestock and pets, it seems likely that the majority that emerge in the future, and which could threaten or devastate human health, will come from animals. Only 10 years ago, the first comprehensive pathogen list was compiled for humans; we still have no equivalent for animals. Here we describe the creation of a novel pathogen database, and present outputs from the database that demonstrate its value.     

Testing hypotheses about fecundity, body size and maternal condition in fishes

Recent research suggests that maternal condition positively influences the number of eggs spawned in fishes. These studies commonly choose a priori to use body length rather than weight as an explanatory variable of offspring production, even though weight is usually the better predictor of fecundity. We are concerned that consistent exclusion of body weight as a predictor of egg production inflates the variance in fecundity attributable to maternal condition. By analysing data on three populations of Atlantic cod (Gadus morhua, Gadidae) and 10 populations of brook trout (Salvelinus fontinalis, Salmonidae), we illustrate the need for a statistically defensible method of model selection to distinguish the effects of maternal condition on egg production from the effects of body size alone. Forward stepwise regression and null model analyses reveal how length‐based regressions can significantly over‐estimate correlations between condition and fecundity, leading us to conclude that the effect of condition on egg productivity may not be as ubiquitous or as biologically important as previously thought. Our work underscores the need for greater statistical clarity in analyses of the effects of maternal condition on reproductive productivity in fishes.