In mate recognition systems, the functional necessity to coordinate traits involved in sexual communication should result in reduced pairing potential for new variants outside the distribution of common reproductive signals. Yet, many closely related, sexual species differ in mate recognition traits, suggesting that directional selection influences the divergence of mate recognition systems. Species of the endemic Hawaiian cricket genus Laupala are morphologically and ecologically cryptic, although both male calling song and female acoustic preference have diverged rapidly between closely related species. These mate recognition phenotypes are therefore often likely to be speciation phenotypes, i.e. traits whose divergence contributes, directly or indirectly, to a reduction of gene flow during speciation, given their frequent participation in early lineage divergence. We conducted a replicated, quantitative trait loci (QTL) mapping study of the genetic basis of differences in male calling song between two closely related species, Laupala paranigra and Laupala kohalensis, allowing us to examine the genetic basis of traits involved in rapid speciation. We found statistical support for eight QTL in one replicate, with at least four of these QTL mapping to the same regions in a second replicate. QTL effects ranged between 3.0% and 10.7% of the difference in pulse rate between L. paranigra and L. kohalensis, and are thus of moderate to small effect. All QTL identified show directional effects consistent with the hypothesis of directional selection. Thus, we conclude that rapid speciation can occur under the influence of many genes of moderate to small effect. This study implicates the role of directional selection in the divergence of mate recognition traits and speciation the Hawaiian cricket genus Laupala.

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These patterns suggest higher rates of gene flow among sites at similar altitudes than along transects, a process that could assist altitudinal adaptation. Patterns of spatial autocorrelation and isolation by distance changed with altitude and may reflect altered patterns of dispersal via pollen and/or seed. There was evidence for selfing and clonality in neighbouring plants. Levels of gene flow along transects were insufficient to prevent adaptive changes in morphological traits, given previously measured levels of selection.

The integron/gene cassette system contributes to lateral gene transfer of genetic information in bacterial communities, with gene cassette-encoded proteins potentially playing an important role in adaptation to stress. Class 1 integrons are a particularly important class as they themselves seem to be broadly disseminated among the Proteobacteria and have an established role in the spread of antibiotic resistance genes. The abundance and structure of class 1 integrons in freshwater sediment bacterial communities was assessed through sampling of 30 spatially distinct sites encompassing different substrate and catchment types from the Greater Melbourne Area of Victoria, Australia. Real-time PCR was used to demonstrate that the abundance of intI1 was increased as a result of ecosystem perturbation, indicated by classification of sample locations based on the catchment type and a strong positive correlation with the first principal component factor score, comprised primarily of the heavy metals zinc, mercury, lead and copper. Additionally, the abundance of intI1 at sites located downstream from treated sewage outputs was associated with the percentage contribution of the discharge to the basal flow rate. Characterization of class 1 integrons in bacteria cultured from selected sediment samples identified an association with complete Tn402-like transposition modules, and the potential for coselection of heavy-metal and antibiotic resistance mechanisms in benthic environments.

Crickets of the genus Laupala represent one of the many morphologically cryptic groups of insects, with the most closely related species distinguished only by the male calling song. Cryptic groups provide a challenge in determining the genetic boundaries between closely related populations and species. We have addressed the question of species boundaries in the Hawaiian cricket, Laupala, using nuclear DNA patterns sampled by the amplified fragment length polymorphism (AFLP) technique. This method has been used widely by plant researchers to facilitate the rapid assessment of genetic diversity in very closely related species and varieties. The AFLP technique is simple and robust, can be applied to any organism, and overcomes problems associated with cost, development time, information content and reproducibility that can plague other marker systems. Our results support previously hypothesized taxonomic relationships among sympatric populations and suggest close genetic relationships among allopatric, conspecific populations.

The divergence of premating behavior and morphology plays a primary role in speciation, and an understanding of the genetic architectures of these phenotypes is essential for the evaluation of models of the speciation process. However, our empirical knowledge of the genetics underlying speciation-related traits remains limited. In this article, we argue that a dissection of specific aspects of the genetic architecture of such traits in a comparative context can allow us to rule out some mechanisms of divergence. We discuss these ideas with reference to our investigation of intersexual communication behaviors involved in mate recognition in the Hawaiian cricket genus Laupala. Different species of Laupala sing distinctively and show species-specific acoustic preferences. We focus on the sister species Laupala paranigra and Laupala kohalensis, characterized by differences in these classic courtship phenotypes. We discuss our preliminary results on the directionality of effect of substituted alleles underlying these species differences. We then discuss these results in the context of historical inference, a necessary perspective for testing the genomic predictions made by theories of speciation that focus on evolution of mate recognition systems.

A new trimethoprim resistance determinant, designated dhfrX, was identified in the In7 integron of pDG0100. The sequence of the dhfrX dihydrofolate reductase is up to 28% identical to the sequences of several known dihydrofolate reductase proteins. The dhfrX gene is adjacent to the second 3'-conserved segment of the In7 integron, but the first 77 bases of this segment are not present.

SummaryCandidate genes for quantitative trait loci have been studied in a Medium Peppin Merino flock. Obvious candidates for effects on wool production traits are genes for the major proteins expressed in the wool fibre, the keratin and keratin‐associated protein genes. Two keratin‐associated protein loci, KRTAP6 and KRTAP8, have previously been shown to be linked. The results of analyses between these two loci and production traits gave significant evidence of linkage with wool fibre diameter in one out of eight halfsib groups tested. High‐glycine‐tyrosine proteins (KRTAP6, 7 and 8) are known to vary considerably in abundance in wool fibres and it is possible that a gene for major effect on fibre diameter is located within the same chromosomal region as KRTAP6 and KRTAP8.