Variations in attack behaviours between Glossina palpalis gambiensis and G. tachinoides in a gallery forest suggest host specificity

Tsetse flies Glossina palpalis gambiensis and G. tachinoides are among the major vectors of sleeping sickness (Human African Trypanosomiasis‐HAT) and nagana (African Animal Trypanosomiasis – AAT) in West Africa. Both riparian species occur sympatrically in gallery forests of south west Burkina Faso, but little is known of their interspecies relationships although different authors think there may be some competition between them. The aim of this study was to check if sympatric species have different strategies when approaching a host. A man placed in a sticky cube (1 m × 1 m × 1 m) and a sticky black‐blue‐black target (1 m × 1 m) were used to capture tsetse along the Comoe river banks in a Latin Square design. The number and the height at which tsetse were caught by each capture method were recorded according to species and sex. Glossina p. gambiensis was more attracted to human bait than to the target, but both species were captured at a significantly higher height on the target compared with the human bait (P < 0.05). No significant difference in heights was found between G. tachinoides and G. p. gambiensis captured on targets (33 and 35 cm, respectively, P > 0.05). However, catches on human bait showed a significant difference in height between G. tachinoides and G. p. gambiensis (22.5 and 30.6 cm, respectively, P < 0.001). This study showed that these sympatric species had different attack behaviours to humans, which is not the case with the target. The implications of these findings are discussed.     

Lizards as model organisms for linking phylogeographic and speciation studies

Lizards have been model organisms for ecological and evolutionary studies from individual to community levels at multiple spatial and temporal scales. Here we highlight lizards as models for phylogeographic studies, review the published population genetics/phylogeography literature to summarize general patterns and trends and describe some studies that have contributed to conceptual advances. Our review includes 426 references and 452 case studies: this literature reflects a general trend of exponential growth associated with the theoretical and empirical expansions of the discipline. We describe recent lizard studies that have contributed to advances in understanding of several aspects of phylogeography, emphasize some linkages between phylogeography and speciation and suggest ways to expand phylogeographic studies to test alternative pattern‐based modes of speciation. Allopatric speciation patterns can be tested by phylogeographic approaches if these are designed to discriminate among four alternatives based on the role of selection in driving divergence between populations, including: (i) passive divergence by genetic drift; (ii) adaptive divergence by natural selection (niche conservatism or ecological speciation); and (iii) socially‐mediated speciation. Here we propose an expanded approach to compare patterns of variation in phylogeographic data sets that, when coupled with morphological and environmental data, can be used to to discriminate among these alternative speciation patterns. [Correction made after online publication (28/07/2010): (minor deletion in the last line of the abstract)].     

Periphyton biomass dynamics in gravel bed rivers: the relative effects of flows and nutrients

SUMMARY. 1. Periphyton chlorophyll a and ash free dry weight (AFDW) were monitored in nine rivers to examine the relative importance of flows and nutrients for regulating periphyton biomass in gravel bed rivers. 2. Mean annual flows in the rivers ranged from 0.94 to 169 m³ s^?1, mean dissolved reactive phophorus (DRP) from 1.3 to 68 μ g 1^?1, periphytic chlorophyll a from 4.6 to 73 mg m ^?2. and AFDW from 2.8 to 16 g m^?2. 3. For eight of the nine rivers NH₄-N. DRP, total Kjeldahl nitrogen, total phosphorus and total suspended solids were correlated (P<0.01) with flow, and for seven rivers conductivity was inversely correlated (P<0.05) with flow. 4. There was a hyperbolic relationship between flows and biomass, with chlorophyll a >100 mg m ^?2 and AFDW >20 g m^?2 occurring most frequently in flows of <20 m³ s^?1. 5. Floods prevented the development of medium term (i.e. up to 2 months) maxima in biomass in five of the rivers, but maxima occurred over summer-autumn and winter-spring in the three rivers where floods were absent. 6. Chlorophyll a biomass was more resistant to flooding than AFDW. Only 5993 of the forty-six recorded floods caused chlorophyll a scouring, whereas 74% of the floods caused AFDW scouring. The efficiency of scour was more influenced by the pre-flood biomass than the magnitude of the event. 7. Biomass maxima were significantly correlated (P<0.01) with mean DRP concentration during the accrual period. Overall, up to 53% of the mean annual biomass difference between rivers was explained by the mean annual DRP concentrations. However, the high correlations between nutrient concentrations and flow indicated that the nutrient data were also carrying hydrological information and that simple causal relationships between nutrients and biomass are difficult to establish in rivers. 8. It is concluded that hydrological factors contribute at least equally with nutrients to the differences in periphyton biomass between the gravel-bed study rivers. They combined to explain up to 63.3% of the variance in biomass, compared with 57.6% for nutrients. It is recommended that periphyton data from gravel-bed rivers should always be viewed within the context of the flow history of the site, and not just as a function of nutrient concentrations.     

A taxonomic and biological review of the tetramoriine ant genus Rhoptromyrmex (Hymenoptera: Formicidae)

Available data on the tetramoriine ant genus Rhoptromyrmex Mayr are reviewed. The genus is redefined for all castes and the monotypic genus Hagioxenus Forel, formerly placed in the Monomorium-group , is synonymized with Rhoptromyrmex. A new species (caritus) is described from Uganda and keys to known workers, females and males are presented. Nest founding by the females, two of which appear autoparasitic and two of which are inquilines, is discussed and the evolutionary pathway of inquilines reviewed. Current taxonomic data on all species are summarized.     

The Localization and Potential Function of Glycosyltransferases in Chick Embryos

Intact, developing chick embryos (stages 9+ to 14) incorporatesugars from sugar nucleotides in patterns which vary accordingto the sugar nucleotide used, the area of the embryo, and theage of the embryo. Radioautographs of the notochord-somite-lateralplate mesoderm vicinity, the optic vesicle-skin ectoderm junction,and the area vasculosa are presented. It is possible that thesepatterns represent localized cell surface glycosyltransferase-glycosylacceptor complexes. However, other possibilities have not beenruled out. The potential role of enzyme-substrate complexesin intercellular interactions is discussed.     

Rates of litterfall and organic matter turnover at three South Australian indigenous forest sites

A quantitative study of the litterfall rate, litter mass and the organic carbon content of litter and soil at three South Australian low open-forests was made monthly for 2 years. The soil and dominant vegetation at the sites were similar, but the mean annual rainfall differed; 635, 690 and 1050 mm respectively at the ‘dry’, ‘medium’ and ‘wet’ sites. Mean annual litterfall at the dry, medium and wet sites was 114, 205 and 233 g m^?2 respectively, and the mean mass of the litter layer was 885, 1153 and 858 g m^?2 Leafy material formed 82% of the litterfall at each site and maximum fall occurred in the summer. Leafy material formed 64–68% of the three litter layers and there was no general pattern of seasonal change of mass. The data obtained were used to calculate the half-life (T_1/2 of the litter, the values were 5.4, 3.9 and 2.6 years respectively at the dry, medium and wet sites. The values from the medium and wet sites fit within the range previously recorded for other open-forests and low open-forests, but indicate an extremely slow rate of decomposition at the dry site, which was located close to open-scrubland. The amounts of organic carbon in the 0–8 cm layer of soil at the dry, medium and wet sites were 777, 928and 950 g m^-2 respectively. However, without a detailed investigation of the source of soil carbon, these values could only be used to show that the organic carbon store to a depth of 8 cm is equivalent to 9–15 times the annual litterfall input.