Circular Ribosomal RNA Genes Are a General Feature of Schizopyrenid Amoebae

ABSTRACT We have recently shown that the ribosomal RNA genes of the amoebo-flagellate Naegleria gruberi Schardinger, 1899, strain NEG-M are carried exclusively on a 14 kilobasepair plasmid. To explore the distribution of this unique gene arrangement, we have examined another strain of N. gruberi and four other species from the order Schizopyrenida. All have this unusual gene arrangement although the size of the plasmid varies widely. Species groups based on morphological criteria do not agree with those resulting from comparison of plasmid restriction enzyme patterns.     

Species‐specific PCR primers for the mitochondrial genome control region hypervariable region 1 of the reef fish Lutjanus sebae

Lutjanus sebae is an important commercial and recreational fish found throughout the Indo‐West Pacific region. Using universal primers for the mitochondrial genome control region hypervariable region 1 (HVR1), we isolated a 385‐bp fragment of HVR1 then designed specific primers near each end of this sequence in the conserved regions flanking the hypervariable region. These primers were shown to yield good quantity and quality of product and to be species specific. Of 20 L. sebae studied, there were eight segregating sites and eight haplotypes. These primers will provide a useful tool for population genetics studies, identification of larvae and eggs and for wildlife forensics.     

Expressed sequence tag‐derived microsatellites for the cool‐water marine copepod Calanus finmarchicus

The copepod Calanus finmarchicus is the major contributor to zooplankton biomass in the North Atlantic and Norwegian Sea, but recent studies have shown a 70% decrease in abundance as well as a northward shift in the species’ range. Insights into dispersal capabilities gained from population genetic studies will be crucial in predicting the response of C. finmarchicus communities to climate change and, consequently, we have developed a set of expressed sequence tag‐derived microsatellite markers to allow fine‐scale elucidation of population structuring and dispersal. Ten polymorphic markers displayed between two and 19 alleles, with levels of expected heterozygosity ranging from 0.044 to 0.924.     

Barred Owl Space Use and Habitat Selection in the Eastern Cascades,Washington

ABSTRACT Competition with barred owls (Strix varia varia) is an important factor contributing to the continued decline of threatened northern spotted owl (Strix occidentalis caurina) populations in the Pacific Northwest, USA, but basic information on habitat selection and space use patterns of barred owls is lacking for much of the region. We investigated space use and habitat selection by tracking radiotagged barred owls in the Eastern Cascade Range of Washington, USA, from 2004 to 2006. We surveyed for barred owls across the 309-km² study area and confirmed presence of barred owl pairs at 21 sites. We collected movement data on 14 barred owls from 12 sites. Mean annual 95% fixed-kernel home-range size was 194 ha for females (n = 4, SD = 70) and 288 ha for males (n = 5, SD = 114). Home ranges were located more frequently than expected in areas with low topographic position, gentle slopes, large overstory tree-crown diameter, high normalized difference vegetation index (NDVI), overstory tree canopy closure >72%, and a moderate amount of solar insolation. Within home ranges, areas that had large tree-crown diameters, low topographic positions, and gentle slopes were used more frequently than expected. The resource selection function we developed for barred owls in our study area indicated that barred owls used areas with the combination of low values for topographic position and slope and higher values for NDVI, solar insolation, and an interaction term for canopy closure and tree-crown diameter. In comparison to published information on northern spotted owls, barred owls used areas with similar canopy closure and tree size classes, but barred owl home ranges were much smaller and more concentrated on gentler slopes in valley bottoms. This information may contribute to the development of management practices that maintain forest characteristics appropriate for spotted owl habitat and prey in areas where spotted owls are least likely to be excluded by territorial barred owls in the Eastern Cascades of Washington.     

Vision and the foraging technique of Great Cormorants Phalacrocorax carbo: pursuit or close‐quarter foraging?

Predatory diving birds, such as cormorants (Phalacrocoracidae), have been generally regarded as visually guided pursuit foragers. However, due to their poor visual resolution underwater, it has recently been hypothesized that Great Cormorants do not in fact employ a pursuit-dive foraging technique. They appear capable of detecting typical prey only at short distances, and primarily use a foraging technique in which prey may be detected only at close quarters or flushed from a substratum or hiding place. In birds, visual field parameters, such as the position and extent of the region of binocular vision, and how these are altered by eye movements, appear to be determined primarily by feeding ecology. Therefore, to understand further the feeding technique of Great Cormorants we have determined retinal visual fields and eye movement amplitudes using an ophthalmoscopic reflex technique. We show that visual fields and eye movements in cormorants exhibit close similarity with those of other birds, such as herons (Ardeidae) and hornbills (Bucerotidae), which forage terrestrially typically using a close-quarter prey detection or flushing technique and/or which need to examine items held in the bill before ingestion. We argue that this visual field topography and associated eye movements is a general characteristic of birds whose foraging requires the detection of nearby mobile prey items from within a wide arc around the head, accurate capture of that prey using the bill, and visual examination of the caught prey held in the bill. This supports the idea that cormorants, although visually guided predators, are not primarily pursuit predators, and that their visual fields exhibit convergence towards a set of characteristics that meet the perceptual challenges of close-quarter prey detection or flush foraging in both aquatic and terrestrial environments.     

Host relations, life cycles and multiparasitism in some parasitoids of aphidophagous Syrphidae (Diptera)

Abstract. 1. Records of parasitism from the field and host choice experiments suggest that most parasitoids of syrphids are monophagous. A few are oligophagous.
2. To elicit egg release, females require a stimulus from the host haemolymph. Differential response to haemolymph cues by females may account for the observed pattern of host relations.
3. Differences in host ranges and timing of female flight periods probably characterize most of the parasitoids studied.
4. In one case of two monophagous parasitoids, Diplazon pectoratorius (Thunberg) and Syrphophilus tricinctorius (Thunberg) attacking the same host Syrphus ribesii (L.) no partitioning was found. Stricinctorius is, however, a superior intrinsic competitor.     

Growth and Antithraquinone Biosynthesis by Galium mollugo L. Cells in Batch and Chemostat Culture

The kinetics of growth, nutrient uptake, and anthraquinone biosynthesisby suspension cultures of Galium mollugo L. cells were examinedin batch and continuous (chemostat) culture. In batch culture,although the initial growth rate was constant (minimum doublingtime = 35 h) characteristic changes in cell composition wereobserved during the growth cycle particularly cell dry weight(between 3.9 and 9.2 g/10⁹ cells), cell anthraquinone (22–80mg/10⁹ cells), and cell protein (0.7–1.6 g/10⁹ cells).Using a chemostat steady state growth was established at twodifferent specific growth rates with mean doubling times of40 h and 25 h. Phosphate was established as the growth-limitingnutrient in chemostat culture at a concentration of 11 µgP ml^–1. In steady state growth at a doubling time of 40h the cell composition remained constant although this was differentfrom any cells grown in batch culture. The cell anthraquinonelevel in steady state growth was between 7 and 30 times lowerthan in batch culture. This result raises the question of therelative importance of growth rate and the growth-limiting nutrientin determining accumulation of secondary products by culturedplant cells.     

Soft Rot Erwinia Bacteria in the Atmospheric Bacterial Aerosol

Using a Casella High Volume Airborne Bacteria Sampler, the soft rot coliform bacteria Erwinia carotovora var. carotovora and E. carotovora var. atroseptica were caught from the open air during rainfall in mid to late summer, autumn and early winter, but not in late winter, spring or early summer. They were not found every time it rained, and never when the weather was dry. The bacteria were caught close to potato crops, but there were several occasions when they were found at sites where there were no such crops or at times of year after potato crops had been harvested. The sources of the organisms are uncertain, but those obtained close to potato crops may have originated there. The results are considered to provide further evidence that airborne spread and subsequent deposition of viable bacteria could cause contamination of Erwinia -free potato stocks, and suggest that rainfall is a major generator of the general atmospheric bacterial aerosol.     

Rabbits and the failure of regeneration in Australian arid zone Acacia

Three experiments are reported concerning the effect of rabbit grazing (Oryctolagus cuniculus L.) upon the recruitment of Acacia seedlings to populations in the South Australian arid zone. In western myall woodland (Acacia papyrocaqsa Benth.) under prevailing rabbit and sheep densities, seedlings exposed to grazing by these two herbivores or to rabbits alone were severely pruned, whereas totally protected seedlings grew unchecked. Seedlings of four Acacia species; A. papyrocarpa, A. oswaldii (F. Muell.), A. kempeana (F. Muell.) and A. burkittii (F. Muell. ex Benth.) were transplanted into four 50 m × 50 m rabbit-proof enclosures. Six rabbits were introduced into each enclosure and within 24 h half of the total seedling population had been grazed. This was at a seedling dry weight ratio of 1|150 000 of the total fodder on offer. In one of the enclosures no seedlings were eaten and there is evidence to suggest that a dense patch of grass had a buffering effect, reducing grazing pressure. Small shoots cut from old Acacia and transferred to the ground throughout 1000 ha of western myall woodland were grazed rapidly near rabbit warrens and progressively less rapidly with increased distance from warrens. The experiments demonstrated that even with the lowered post-myxomatosis population densities, rabbit grazing pressure would significantly affect recruitment in arid zone Acacia populations in the absence of stock.