Colour change ability and its effect on prey capture success in female Misumenoides formosipes crab spiders

1. Changing between white and yellow body colour in certain crab spider species has been interpreted as an adaptation for matching the background colour where they hunt and thereby remaining cryptic to prey and/or their own predators. The potential costs and benefits of colour change in female Misumenoides formosipes Walckenaer were investigated via assessment of prey opportunities and capture success, in conjunction with the tendency for and rate of colour change on different backgrounds. 2. It was tested whether being matched or mismatched to their background affected foraging by moving females between white and yellow inflorescences. Female colour was quantified in digital photos using the Lab colour space component of Adobe photoshop , providing the first empirical assessment of the rate of colour change for a crab spider species. 3. Insect visits (potential prey) on inflorescences with and without spiders and prey capture success with females matched and mismatched to their background were quantified. 4. Yellow females abandoned white inflorescences, whereas white females remained on and underwent colour change on yellow inflorescences. This difference supported the notion that the costs of colour change differ depending on the starting colour. Female departures from white flowers were apparently not due to a lack of insect visitation, as white inflorescences had higher visitation rates than did yellow inflorescences, even in the presence of spiders. 5. An increase in the prey capture success of females who transitioned from white to yellow body colour on a yellow background supported the hypothesis that colour matching functions to deceive prey.     

Change to a diatom assemblage in a eutrophic lake following point source nutrient re-direction: a palaeolimnological approach

SUMMARY. 1. Lough Augher, Co. Tyrone, Northern Ireland, underwent eutrophication as a result of untreated effluent disposal by a local creamery, from 1900 until 1972–73, when primary sewage treatment began. When this remedial action met with limited success the effluent was redirected to the River Blackwater, downstream of the lake 2. A sediment core taken in July 1981 shows an unambiguous record of the diatom response to this eutrophication; the species succession represents a clear eutrophication gradient, with a shift from mesotrophic plankton forms (Aulacoseira ambigua, Asterionella formosa, Fragilaria crotonensis, Diatoma tenue var. elongatum) to a variety of small Stephanodiscus spp. typical of very eutrophic conditions (S. parvus, S. hantzschii). The succession is in reasonable agreement with that predicted by changing Si:P ratios. 3. A second, short core, taken in September 1985, shows dramatic changes in the diatom plankton after 1981, with resurgences and rapid increases of species present early in the lake's eutrophication, and representative of mesotrophic conditions. There is clear agreement between the biostratigraphic record of the two cores, for the time period during which they overlap, c. 1970–81. 4. The available chemical data post-dates the re-direction of the creamery effluent. However, it indicates that the phosphorus concentration is in equilibrium with the loading, and has stabilized following effluent re-direction. There were no significant differences for chlorophyll a and total phosphorus between the years for which data are available. The mean concentrations were 10, 14 and 10 g 1^?1 chlorophyll a, and 61, 63 and 58 g TP 1^?1 in 1978, 1979 and 1982 respectively. 5. A Correspondence Analysis Joint-plot is used to summarize the biostratigraphy of the two cores. It serves as an ecological summary of the responses of the plankton diatoms to changing nutrient concentrations and ratios, following redirection of the creamery effluent, and demonstrates clearly the new direction taken by the planktonic diatoms. Although the phosphorus and chlorophyll a data suggest that the lake returned quickly to an equilibrium state, the diatom community continued to change. suggesting a time-lag effect and non-equilibrium responses by the planktonic diatoms to their nutrient environment. 6. The potential value of palaeolimnological approaches to long- and medium-term monitoring of diatom plankton changes should not be underestimated; they may provide an important time component for limnological restoration projects.     

Life history and ecological role of the xylophagous aquatic beetle, Lara avara LeConte (Dryopoidea: Elmidae)

SUMMARY.

• 1 This study documents the life history of the xylophagous elmid beetle, Lara avara, and estimates its contribution to wood degradation in Oregon streams. The life cycle was found to be 4 to 6 or more years long, with all but 2–3 months of that spent in the larval stage.
• 2 Larvae grow through seven instars, taking about 1 year for instars 1–3, and from 3 to 5 or more years for instars 4–7.
• 3 Last-instar larvae leave the water to pupate. Adults live approximately 3 weeks and occur from May to August. The eggs are deposited on submerged wood.
• 4 Larvae probably obtain their nutrition by absorbing substances liberated into decaying wood by microbial activity. They do not produce their own cellulase, nor do they have a symbiotic gut flora similar to that of xylophagous cranefly (Tipulidae) larvae.
• 5 Faecal production by L. avara larvae averaged 13% dry body wt d^-1. This yields an estimate of faecal production of 1.6 g m^-2 y^-1 in Oregon Coast Range streams (about 0.3% y^-1 of wood standing crop).

     

Sporulation of Marteilioides branchialis N. Sp. (Paramyxea) in the Sydney Rock Oyster, Saccostrea commercialis: An Electron Microscope Study

ABSTRACT The ultrastructure of sporulation of a new parasite, Marteilioides branchialis (Paramyxea), in the Sydney Rock oyster, Saccostrea commercialis , is described. The development is typical of other Paramyxea whereby a stem cell internally cleaves a secondary cell contained within a vacuole. It differs from other species in the phylum in that each secondary cell produces a single spore composed of two concentric cells, one within a vacuole of the other. This type of sporulation represents the simplest of all known Paramyxea. Infection results in focal gill lesions and was observed concurrently with an epizootic of another paramyxean, Marteilia sydneyi .     

Opisthosomal fusion and phylogeny of Palaeozoic Xiphosura

Fusion of opisthosomal tergites to form a thoracetron has previously been considered a characteristic of the xiphosuran superfamilies Euproopoidea Eller, 1938, and Limuloidea Zittel, 1885. Evidence is presented here that fusion also occurs in Bellinuroidea Zittel & Eastman, 1913. Results of a cladistic analysis of Palaeozoic xiphosuran genera indicate that Synziphosurina Packard, 1886, is a paraphyletic assemblage of stem-group Xiphosura. Superfamily Paleolimulidae superfam. nov. is erected for families Paleolimulidae Raymond, 1944, and Moravuridae P&íbyl, 1967.     

Glandular lesions of the cervix—cytological and histological correlation

In this retrospective review we assessed the frequency with which atypical glandular cells in cervical smears predict cervical glandular lesions. Asymptomatic patients (n=34) with one or more smears showing atypical glandular cells and subsequent histopathological assessment were studied. Independent cytological and histological review was undertaken. Cytological review confirmed atypical glandular cells in 29 cases, 17 of which had coexisting squamous dyskaryosis. Histological review of these 29 cases revealed glandular neoplasia in 13 (45%) and microglandular hyperplasia (MEH) in an additional four (14%). Initial reporting had underestimated the prevalence of glandular neoplasia.