Electrophoretic keys to identify members of the Anopheles punctulatus complex of vector mosquitoes in Papua New Guinea

Abstract. Electrophoretic keys are given for the six species of the Anopheles punctulatus complex (Diptera: Culicidae) known from Papua New Guinea plus An.farauti No. 2 and No. 3 from Australia. The categories ‘faster’, ‘standard’ and ‘slower’ are used in keys to relate allozyme band migration following cellulose acetate electrophoresis to the standard pattern. Alternative keys are given depending on the availability of different species for use as standards.     

Competition on a divided and ephemeral resource: a cage experiment

This paper describes an experimental test of the 'aggregation' model of coexistence. With patches, the two species coexist. Without patches, the inferior competitor is eliminated.     

Microdistribution and habitat selection in Drosophila subobscura Collin

Microdistribution and habitat selection were investigated in a population of Drosophila subobscura near Leeds, Yorkshire. Microdistribution was examined along a transect running through a deciduous woodland. Two main types of habitat were recognized, those with dry soil and a closed canopy of mature trees (dry and dark) and those with wet soil and an open canopy of mature trees (wet and light). Flies were much more frequent, judged by their attendance at baited traps, in the dry/dark habitat. Flies taken from both habitat types, marked with different coloured fluorescent dust and released at a point mid-way between the original habitats, tended to return to their area of initial capture.     

Desiccation and Free Radical Mediated Changes in Plant Membranes

Senaratna, T., McKersie, B. D. and Borochov, A. 1987. Desiccationand free radical mediated changes in plant membranes.—J.exp. Bot. 38: 2005-2014. In vitro treatment of microsomal membranes from the axes ofsoybean (Glycine max (L.) Merr.) seeds with free radicals simulatesthe type of membrane injury observed following a lethal desiccationstress—the accumulation of free fatty acids in the membranebilayer, the loss of lipid-P, and the formation of gel phasedomains. The major phospholipids in the microsomal fractionwere phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol.Although these treatments induced an extensive loss of totalphospholipid from the microsomal fraction following desiccation,the ratio of the major phospholipids remained unchanged. Neitherlysophosphatides nor phosphatidic acid accumulated in the fraction,but free fatty acid levels increased. Therefore, cleavage ofboth acyl chains from the phospholipid molecule occurred followingdesiccation of the axes and in vitro free radical treatmentof the membrane. Both treatments also promoted formation of gel phase domainsas shown by wide angle x-ray diffraction and increased microviscosityas determined by the fluorescent probe, DPH (1,6-diphenyl-1,3,5-hexatriene).This could be simulated in liposomes prepared from the totalmicrosomal lipid fraction by the addition of saturated freefatty acids (16:0 and 18:0) at the levels observed followingstress. In contrast, the addition of unsaturated fatty acidsperturbed the bilayer and reduced microviscosity. The inclusionof both saturated and unsaturated free fatty acids as observedin vivo promoted a response similar to that observed with onlythe addition of the saturated free fatty acids. Desiccation of the axes also promoted a loss of microsomal protein,which was recovered in the 165 000 x g supernatant, and an apparentloss of thiol groups from the membrane as determined by a thiolspecific fluorescence probe, dansylaziridine. This loss of thiolgroups could also be simulated by exposure of the membranesto gamma irradiation, which was used as a non-enzymatic sourceof free radicals. Collectively, these data support the hypothesisthat membrane disassembly following desiccation stress is mediatedby a free radical mechanism, and that the consequent de-esterificationof membrane phospholipid and accumulation of saturated freefatty acids alter the physical properties of the membrane. Key words: Membrane microviscosity, membrane fluidity, free fatty acids     

Nest Turnover Rates and List-Frame Decay in Bald Eagles: Implications for the National Monitoring Plan

ABSTRACT In accordance with federal regulations, the United States Fish and Wildlife Service developed a postdelisting monitoring plan for the bald eagle (Haliaeetus leucocephalus) designed to detect a change in the number of occupied nests on a national scale. The plan employs a dual-frame approach to the survey design where a list frame (list of known nests) and an area frame (set of survey plots) are used in concert to estimate the number of occupied nests in 5-year intervals over a 20-year period. The plan offers no provisions for changes in list-frame integrity, nor does it contemplate the impact of such changes on survey performance. We used a long-term data set to quantify occupancy patterns for nests in Virginia, USA, and evaluated their influence on integrity of the list frame and performance of the proposed dual-frame monitoring approach. The average annual turnover rate for nests was 0.261, resulting in a rapid decay of the list frame. Decay of the list frame leads to a functional collapse of the dual-frame approach, down to the area-frame survey alone, early within the monitoring time horizon. This early decay of the list frame implies that the area-frame coverage needed to maintain the same statistical power as stated in the monitoring plan would have to be increased by a factor of 3 to 5 beyond that recommended in the current plan. Remedies for this deficiency undermine the cost benefit associated with inclusion of the list frame. We examined response of the dual-frame survey to variation in nest turnover rates and population growth rates and defined a state space where time to collapse is beyond the proposed 20-year time horizon. Because, under realistic estimates of turnover rates, the dual-frame approach collapses to the area frame within the proposed monitoring window, we recommend that the costs of list-frame maintenance be included in the procedure to optimize allocation of survey effort.     

Impacts of passage migrant songbirds on behaviour and habitat use of resident Sardinian Warblers Sylvia melanocephala in Gibraltar

Explanations for the coexistence of migratory and sedentary (resident) birds are much debated: some authors have suggested that migrants make use of surplus resources not exploited by residents, whereas others have recorded ecological shifts in residents during periods when migrants are present. These shifts have been ascribed to the presence of migrants but could equally reflect seasonal variation in the distribution of resources required by sedentary species. Here we assess how the abundance of migrants affects the territorial behaviour and habitat use of resident Sardinian Warblers Sylvia melanocephala at a stop‐over site on the Rock of Gibraltar. There was a significant positive relationship between the abundance of migrants and the distances moved, time spent calling and the species and functional diversity of plants used by Sardinian Warblers on a daily basis, suggesting that migrants have a significant impact on residents.     

The Zambezi River in Moçambique

SUMMARY. Surveys of the physico-chemical status of the River Zambezi in Moçambique were conducted between April 1973 and May 1974, to characterize the river prior to the closure of the Cabora Bassa Dam and to provide baseline data from which future changes in the river ecosystem can be followed. The temperature of the river water increases by about 3°C from Lake Kariba to the sea, and with an average pH of 7.8 the water is slightly more alkaline than Kariba Dam water. The river is well oxygenated with no sign of hydrogen sulphide. Transparency is generally very low and changes are mainly determined by the floods of local tributaries. The overall average total alkalinity is 55 mg 1^?1 CaCO₃, with no regular seasonal variation, average concentrations of chloride and sulphate are respectively, 5.4 mg 1^?1 Cl^? and 5.3 mg 1^?1 SO^2-₄. They increase under both the influence of the ionically rich Shire River and the sea; the latter due to vertical mixing. Total hardness and calcium hardness behave in a similar way, while conductivity and silica concentrations increase slightly until the Zambezi—Shire confluence, at which point, conductivity increases by 25% to an average peak value of 153 μS cm^?1, and silica decreases by 15% to a minimum average value of 15.5 mg 1^?1 SiO₂. Ammonia and nitrate concentrations show a clear seasonal variation, with respectively, minimum dry season and maximum wet season average values of about 0.05 mg 1^?1 and 0.3 mg 1^?1. The overall average concentration of nitrite is 0.004 mg 1^?1. Orthophosphate in the river is mostly affected by Lake Kariba, though other sources are also of some importance. Maximum average concentrations of about 0.4 mg 1^?1 PO^3-₄ were recorded during the dry season after the overturn of Lake Kariba. The concentration of dissolved metals is mainly determined by the outflow of Kariba and by the Shire River, with only K and Mg apparently affected by the outflow from Lake Kafue. It is concluded that the water quality of the Middle Zambezi is mainly determined by the Kariba Dam, with the Kafue Dam playing a minor role. At the time of the pre-impoundment survey, the main impact on water quality of the Lower Zambezi came from the Shire River. With the addition of yet another large reservoir on the Zambezi, in the form of Cabora Bassa, together with the appreciable effect of tributary rivers on the lake, and the likely increased impact of the Shire River on the now more regulated river, the quality of the Lower Zambezi is expected to alter considerably, with concomitant ecological changes.     

Some Factors Involved in the Control of Microtubule Assembly in Sea Urchins

Some recent evidence is discussed which suggests that the controlof microtubule assembly during the formation of the mitoticapparatus in sea urchins involves three factors. These include:nucleation sites such as the kinetochores, a mechanism for regulatingintracellular calcium, and a heat stable substance which preventsspontaneous, non-nucleated microtubule polymerization.