Molecular phylogeny and zoogeography of the freshwater crayfish genus Cherax Erichson (Decapoda: Parastacidae) in Australia

The evolutionary history and biogeography of freshwater-dependent taxa in Australia is of intrinsic interest given the present-day aridity of this continent. Cherax is the most widespread and one of the most species-rich of Australia's nine freshwater crayfish genera. The phylogenetic relationships amongst 19 of the 23 Australian Cherax were established from mitochondrial DNA sequences representing the 12S rRNA and 16S rRNA gene regions. The relationships among species support an initial east–west separation, followed by a north–south divergence in eastern Australia. Molecular clock estimations suggest that these divergences date back to the Miocene. The phylogenetic relationships support endemic speciation within geographical regions and indicate that long-distance dispersal has not led to recent speciation as previously hypothesized. This new evolutionary scenario is consistent with the climatic history of Australia and the evolutionary history of other similarly distributed freshwater-dependent organisms in Australia.

The molecular systematics of Leiopotherapon unicolor (Günther, 1859): testing for cryptic speciation in Australia’s most widespread freshwater fish

Leiopotherapon unicolor is the most widespread freshwater fish species in Australia. A comprehensive allozyme and mitochondrial DNA 16S rRNA data set was assembled from 141 specimens of L. unicolor collected Australia-wide in order to test for cryptic speciation in this far-ranging species. Surprisingly, little genetic diversity was observed within L. unicolor and provided no evidence for the existence of cryptic species within this lineage. In contrast, a small sample set of L. aheneus used as the outgroup showed two highly divergent haplotypes strongly suggestive of cryptic speciation. L. unicolor has a number of ecological and life history attributes that may explain the lack of significant genetic divergence over substantial geographical distances. The occurrence of other widespread fish and crustacean species that also display only limited genetic diversity indicate that climate conditions more favourable to dispersal across central and northern Australia than is suggested by the extent of present-day aridity have occurred in the relatively recent geological past.

Oral zinc sulfate solutions inhibit sweet taste perception

We investigated the ability of zinc sulfate (5, 25, 50 mM) to inhibit the sweetness of 12 chemically diverse sweeteners, which were all intensity matched to 300 mM sucrose [800 mM glucose, 475 mM fructose, 3.25 mM aspartame, 3.5 mM saccharin, 12 mM sodium cyclamate, 14 mM acesulfame-K, 1.04 M sorbitol, 0.629 mM sucralose, 0.375 mM neohesperidin dihydrochalcone (NHDC), 1.5 mM stevioside and 0.0163 mM thaumatin]. Zinc sulfate inhibited the sweetness of most compounds in a concentration dependent manner, peaking with 80% inhibition by 50 mM. Curiously, zinc sulfate never inhibited the sweetness of Na-cyclamate. This suggests that Na-cyclamate may access a sweet taste mechanism that is different from the other sweeteners, which were inhibited uniformly (except thaumatin) at every concentration of zinc sulfate. We hypothesize that this set of compounds either accesses a single receptor or multiple receptors that are inhibited equally by zinc sulfate at each concentration.

Comparing entire colour patterns as birds see them

Colour patterns and their visual backgrounds consist of a mosaic of patches that vary in colour, brightness, size, shape and position. Most studies of crypsis, aposematism, sexual selection, or other forms of signalling concentrate on one or two patch classes (colours), either ignoring the rest of the colour pattern, or analysing the patches separately. We summarize methods of comparing colour patterns making use of known properties of bird eyes. The methods are easily modifiable for other animal visual systems. We present a new statistical method to compare entire colour patterns rather than comparing multiple pairs of patches. Unlike previous methods, the new method detects differences in the relationships among the colours, not just differences in colours. We present tests of the method's ability to detect a variety of kinds of differences between natural colour patterns and provide suggestions for analysis.

Is life history a barrier to dispersal? Contrasting patterns of genetic differentiation along an oceanographically complex coast

Extreme variation in early life-history strategies is considered a moderately good predictor of genetic subdivision and hence dispersal for a range of marine species. In reality, however, a good deal of population differentiation must reflect historical effects, more subtle variation in life histories, and, particularly, the interaction of larvae with oceanographic processes. Using a combination of allozyme and microsatellite markers, we show that the large-scale genetic structure of populations of three species (direct and planktonically developing cushion stars and a planktonic developing sea anemone that is also asexually viviparous) varies consistently, in line with the predicted capacity for dispersal within three geographic regions. We detected high levels of genetic subdivision for the direct developing cushion star (FST = 0.6), low levels for the planktonically developing cushion star (FST = 0.009), and intermediate levels for the sexual/asexual sea anmone (FST = 0.19). These patterns are exhibited despite the highly variable patterns of current movement and the presence of biogeographic barriers. Our results suggest that, although there is large scale genetic differentiation for two species, patterns of population connectivity are remarkably consistent within major regions and do not reflect variation in major oceanographic processes or genetic discontinuity coincident with biogeographic boundaries.

Sorption and Fractionation of Copper in soil at a sewage irrigation farm in Australia

Copper (Cu) is an important heavy metal to be considered in soil contamination, because high concentrations of copper in soil produce toxic effects and may accumulate in plant tissues. In Australia's oldest sewage irrigation farm, located in Werribee, Victoria, soil in the land filtration area is contaminated by Cu. However, Cu content in herbage tissues is in the normal range and has been trending downward since 1979. Therefore, studies on the sorption capacity and sequential extraction of Cu in soil at the Werribee Farm is of significance, not only for better understanding the mechanism of transport, chemical processes, and plant uptake of Cu, but also in providing information for the practical management of sewage farm soils. Methods of combining sorption isotherms with sequential extraction procedures were adopted, and the results showed that the soil in the land filtration area at Werribee Farm has a high sorption capacity for Cu, and distribution coefficients, K_f of Cu, were 629 L kg^-1 in surface soils (0-20 cm) and 335 L kg^-1 in subsurface soils (20-40 cm). The sequential extraction fractions demonstrate that exchangeable and carbonate fractions are very low, only comprising 3.49 to 5.49% of total copper. The other fractions are also discussed. This characteristic of Cu in soil is related to the low concentration of Cu in plant tissues.

Development of twenty-four novel microsatellite markers for the freshwater crayfish, Geocharax gracilis, using next generation sequencing

The crayfish Geocharax gracilis is an important inhabitant of natural and agricultural drainage systems in south-eastern Australia. To investigate population structure, genetic diversity and patterns of connectivity in natural and human-altered ecosystems, we isolated and characterised 24 microsatellite loci using next generation sequencing. Loci were initially tested for levels of variation based on 12 individuals from across the species’ geographical range. A further 33 individuals from a single population were used to test for departures from Hardy–Weinberg equilibrium and linkage disequilibrium. We detected high to moderate levels of genetic variation across most loci with a mean allelic richness of 8.42 and observed heterozygosity of 0.629 (all samples combined). We found no evidence for linkage disequilibrium between any loci and only three loci (Geo01, Geo24 and Geo47) showed significant deviations from Hardy–Weinberg expectations. These same three loci, plus two additional loci (Geo06 and Geo28), also showed the presence of null alleles. These 24 variable markers will provide an important tool for future population genetic assessments in natural and human altered environments.

Response to Islamophobia in the Arabic Islamic discourse: a critical discourse analysis

In the aftermath of September 11, Muslim scholars made numerous attempts to explain Islamophobia from the Islamic perspective; they presented arguments that are not addressed in the Western narrative. Two texts in Arabic by the prominent Muslim preacher, Mohammad Hassan and by the Muslim orator Fadhel Sliman are analysed from a Critical Discourse Analysis (CDA) viewpoint. This analysis aims to demonstrate how language is inextricably linked with ideology. This paper demonstrates that textual strategies in the Arabic Islamic discourse and their ideological implications show distinct characteristics some of which add to the present literature on discourse. The aim of the chosen texts is to educate and create solidarity between the speakers and the audience in fighting Islamophobia. The reliance of the speakers on tactics such as quoting from the Holy Qur’ān and ḥadīth to defend Islam, and choice of words and sentence structures may instigate discussions about the persuasive power of the Arabic Islamic narrative.