Patterns of parasitism in monarch butterflies during the breeding season in eastern North America

1. Migratory behaviour can result in reduced prevalence of pathogens in host populations. Two hypotheses have been proposed to explain this relationship: (i) ‘migratory escape’, where migrants benefit from escaping pathogen accumulation in contaminated environments; and (ii) ‘migratory culling’, where the selective removal of infected individuals occurs during migration. 2. In the host–parasite system between the monarch butterfly (Danaus plexippus Linn.) and its obligate protozoan parasite Ophryocystis elektroscirrha (OE), there is evidence to support both hypotheses, particularly during the monarchs' autumn migration. However, these processes can operate simultaneously and could vary throughout the monarchs' annual migratory cycle. Assessing the relative strength for each hypothesis has not previously been done. 3. To evaluate both hypotheses, parasite infection prevalence was examined in monarchs sampled in eastern North America during April–September, and stable isotopes (δ²H, δ¹³C) were used to estimate natal origin and infer migration distance. There was stronger support for the migratory escape hypothesis, wherein infection prevalence increased over the breeding season and was higher at southern latitudes, where the breeding season tends to be longer compared with northern latitudes. Little support was found for the migratory culling hypothesis, as infection prevalence was similar whether monarchs travelled shorter or longer distances. 4. These results suggest that migration allows individuals to escape parasites not only during the autumn, as shown in previous work, but during the monarchs' spring and summer movements when they recolonise the breeding range. These results imply a potential fitness advantage to monarchs that migrate further north to exploit parasite‐free habitats.     

Distribution and Broadscale Habitat Relations of the Wolverine in the Contiguous United States

ABSTRACT Conservation of the wolverine (Gulo gulo) at the southern extent of its North American range requires reliable understandings of past and present distribution patterns and broad-scale habitat relations. We compiled 820 verifiable and documented records of wolverine occurrence (specimens, DNA detections, photos, and accounts of wolverines being killed or captured) in the contiguous United States from museums, the literature, and institutional archives. We spatially referenced 729 records with areal precision ≤1 township (93.2 km²) and temporal precision ≤10 years. Historical records (1827–1960) were located primarily in the western mountains and Great Lakes region. However, our data suggest that the historical distribution of wolverines in the Cascade Range and Sierra Nevada was disjunct, contradicting previous interpretations. Our results indicate that wolverine range in the contiguous United States had contracted substantially by the mid-1900s. Current records (1995–2005) are limited to north-central Washington, northern and central Idaho, western Montana, and northwestern Wyoming. We investigated potential relations between wolverines and alpine vegetation, cold temperatures, and spring snow cover by comparing the distribution of historical wolverine records with Kuchler's potential natural vegetation types, Holdridge's climatic life zones, and EASE snow-cover maps during the latter portion of the wolverine denning period (15 Apr-14 May). In the western mountains, historical wolverine records generally occurred in or near alpine vegetation and climatic conditions, especially at the limits of their distribution in the Cascade Range, Sierra Nevada, and southern Rocky Mountains. However, the only habitat layer that fully accounted for historical distribution patterns was spring snow cover. Causal factors for the extirpation of wolverines from the southern portions of their range in the contiguous United States are unknown, but are likely related to high levels of human-caused mortality and low to nonexistent immigration rates.     

The dissolution of calcite in acid waters: mass transport versus surface control

SUMMARY. 1. A new experimental method for the study of kinetics and mechanism of reactions at the solid-liquid interface has shown that the dissolution of calcite in acidic waters is, under conditions of high mass transport, controlled by the first order heterogeneous reaction of H⁺ at the interface and not by diffusion as previously thought.
2. The implications of this for lake liming strategies (aimed at countering the effects of 'acid rain') are significant in that under typical liming conditions, the rate of calcite dissolution will be surface controlled and consequently appreciably slower than previously considered.     

Bias and variance in model results associated with spatial scaling of measurements for parameterization in regional assessments

Models are central to global change analyses, but they are often parameterized using data that represent only a portion of heterogeneity in a region. This creates uncertainty in the results and constrains the reliability of model inferences. Our objective was to evaluate the uncertainty associated with differential scaling of parameterization data to model soil organic carbon stock changes as a function of US agricultural land use and management. Specifically, we compared analyses in which model parameters were derived from field experimental data that were scaled to the entire US vs. the same data scaled to climate regions within the country. We evaluated the effect of differential scaling on both bias and variance in model results. Model results had less variance by scaling data to the entire country because of a larger sample size for deriving individual parameter values, although there was a relatively large bias associated with this parameterization, estimated at 2.7 Tg C yr^?1. Even with the large bias, resulting confidence intervals from the two parameterizations had considerable overlap for the estimated national rate of SOC change (i.e. 77% overlap in those intervals). Consequently, the results were relatively similar when focusing on the uncertainty rather than solely on the mean estimate. In contrast, large biases created less overlap in confidence intervals for the change rates within individual climate regions, compared with the national estimates. For example, the overlap in resulting intervals from the two parameterizations was only 32% for the warm temperate moist region, with a corresponding bias of 3.1 Tg C yr^?1. These findings demonstrate that there is a greater risk of making erroneous inferences because of large biases if models are parameterized with broader scale information, such as an entire country, and then used to address impacts at a finer spatial scale, such as sub‐regions within a country. In addition, the study demonstrates a trade‐off between variance and bias in model results that depends on the scaling of data for model parameterization.     

Purification of Eimeria Sporozoites by DE-52 Anion Exchange Chromatography

An anion exchange column of DE-52 has been used to purify Eimeria sporozoites from a post-excystation mixture of oocysts, oocyst shells, sporocysts, sporocyst shells, and sporozoites. The mean recovery from several experiments was 94% and virtually all non-sporozoite material was removed. Infectivity studies in vitro with sporozoites showed that they were viable after purification and were at least as infectious as the unpurified sporozoites; furthermore, oocysts in the crude preparation could be recovered from the DE-52 cellulose by resuspending them in a 20% (w/v) sodium chloride solution.     

Trypanosoma cruzi Infection of BSC-1 Fibroblast Cells Causes Cytoskeletal Disruption and Changes in Intracellular Calcium Levels

ABSTRACT The disruption of vimentin and actin filaments of host BSC-1 fibroblast cells by Trypanosoma cruzi was investigated using a mouse monoclonal anti-vimentin antibody and rhodamine phalloidin, respectively. Indirect immunofluorescence microscopy demonstrated that infection of BSC-1 cells by T. cruzi caused disruption of both cytoskeletal components. The disruption was greater as infection progressed. Mechanisms other than mechanical ones may play a role in the disruption since disrupted cytoskelelal elements were well removed from the parasites. In the determination of intracellular calcium concentrations using Fura-2 AM, infected and uninfected cells both showed an initial increase in intracellular calcium levels. At later times of infection (3 to 5 days), intracellular calcium levels of infected cells were significantly lower than those of control cells. There was no specific localization of intracellular calcium in the infected host cells as determined by image analysis.     

The taxonomic status of Hylopsis platycephalus Werner, 1894 and Centrolenella Noble, 1920 (Amphibia: Anura)

On the assumption that the holotype of the South American frog Hylopsis platycephalus, described by Franz Werner in 1894, had been lost, Lynch (1981) designated a neotype, but in so doing incorrectly associated a centrolenid species with that name. As a result of the neotype designation, the genus Centrolenella Noble, 1920 (Centrolenidae) became a junior subjective synonym of Hylopsis Werner, 1894.
The holotype of Hylopsis platycephalus, which has never been lost, was obtained from the Institut fur Zoologie der Universität Wien and on examination was found to be a species of Sphaenorhynchus Tschudi, 1838 (Hylidae) distinct from other known members of the genus. Centrolenella Noble is thus validated and Hylopsis (ayn. nov.) becomes a junior subjective synonym of Sphaenorhynchus.
The rules of nomenclature relating to the neotype are discussed and Sphaenorhynchus platycephalus comb. nov. is redescribed. The centrolenid species which Lynch (1981) assigned to Hylopsis platycephalus is named Centrolenella savagei sp. nov.     

A revised synopsis of the genus Atractomorpha Saussure, 1862 (Orthoptera:Pyrgomorphidae), with an account of the African aberrans - group

Recent work has shown that the preliminary revision of Atractomorpha by Banerjee & Kevan (1960), while basically not altogether unsatisfactory, is in need of considerable modification. The most important changes made include the recognition, as good species, of a number of taxa previously relegated to synonymy or to subspecific status. Two previously undescribed species have been discovered in the African a&errans-group, and two new subspecies are erected. The conclusions are largely based upon a study of the phallic structures, which had not previously been deemed satisfactory in providing diagnostic characters. The variability of these structures in the various species is illustrated, including that due to immaturity in two of them. The concealed female copulatory structures are also figured. A new key to species and subspecies (as well as an abridged key) is presented. New species are:A. occidentalis and A. orientalis. New subspecies are:A. sinensis montana and A. psittacina affinis. Species resurrected from synonymy are:A. rufopunctata Bolivar, A. himalayica Bolivar, A. angusta Karsch, and A. similis Bolivar, of which A. australiana Bolivar proves to be a synonym, and not a subspecies of A. crenaticeps (Blanchard). The other species re-elevated from subspecific rank is A. rhodoptera Karsch. Further changes in synonymy are as follows:A. lanceolata Bolivar is a synonym of A. burri Bolivar and not of A. rhodoptera; A. dentifrons Bolivar is a synonym of A. similis and not of A. crenaticeps; A. brevicornis (Thunberg) is removed from partial synonymy with A. lata (Motschoulsky). A. blanchardi Bolivar is not synonymous with A. crenulata (Fabricius) but is conspecific with A. acutipennis (Guérin-Méneville) and is here tentatively recognized as a widely distributed south-west Asiatic subspecies (in place of A. brevis Uvarov, which, as now understood, is restricted to south-west Arabia). A. crenulata apparently has a more restricted distribution than previously thought, being largely replaced or complemented by A, angusta, except in India and Ceylon. Neotypes are designated for A. acutipennis blanchardi and for Truxalis oceanicus Montrouzier (=A. crenaticeps). Information regarding the type specimens of all nominal species of Atractomorpha except A. nipponica Steinmann is given, and lectotype designations are made wherever necessary. Photographs of almost all primary types, except that of A. nipponica, that have not previously been so illustrated are present. This last species may be a synonym of A. rufopunctata.