Speciation through sensory drive in cichlid fish

Theoretically, divergent selection on sensory systems can cause speciation through sensory drive. However, empirical evidence is rare and incomplete. Here we demonstrate sensory drive speciation within island populations of cichlid fish. We identify the ecological and molecular basis of divergent evolution in the cichlid visual system, demonstrate associated divergence in male colouration and female preferences, and show subsequent differentiation at neutral loci, indicating reproductive isolation. Evidence is replicated in several pairs of sympatric populations and species. Variation in the slope of the environmental gradients explains variation in the progress towards speciation: speciation occurs on all but the steepest gradients. This is the most complete demonstration so far of speciation through sensory drive without geographical isolation. Our results also provide a mechanistic explanation for the collapse of cichlid fish species diversity during the anthropogenic eutrophication of Lake Victoria.     

A gene in the multidrug and toxic compound extrusion (MATE) family confers aluminum tolerance in sorghum

Crop yields are significantly reduced by aluminum toxicity on highly acidic soils, which comprise up to 50% of the world's arable land. Candidate aluminum tolerance proteins include organic acid efflux transporters, with the organic acids forming non-toxic complexes with rhizosphere aluminum. In this study, we used positional cloning to identify the gene encoding a member of the multidrug and toxic compound extrusion (MATE) family, an aluminum-activated citrate transporter, as responsible for the major sorghum (Sorghum bicolor) aluminum tolerance locus, Alt(SB). Polymorphisms in regulatory regions of Alt(SB) are likely to contribute to large allelic effects, acting to increase Alt(SB) expression in the root apex of tolerant genotypes. Furthermore, aluminum-inducible Alt(SB) expression is associated with induction of aluminum tolerance via enhanced root citrate exudation. These findings will allow us to identify superior Alt(SB) haplotypes that can be incorporated via molecular breeding and biotechnology into acid soil breeding programs, thus helping to increase crop yields in developing countries where acidic soils predominate.     

On new or poorly known Australian Filistatidae spiders (Araneae: Araneomorphae), including a study on the fine morphology of Wandella

I present an update on the taxonomy of the filistatid genera Wandella Gray and Yardiella Gray, both endemic to Australia. Two new species are described: Wandella grayi sp. nov., known from Queensland, and Wandella infernalis sp. nov., known from a single cave in Western Australia. The male of Wandella australiensis (L. Koch) and the females of Wandella stuartensis Gray and Wandella waldockae Gray are described and illustrated for the first time. New records are given for these and other species of Australian filistatids, including the first epigeal records of Yardiella humphreysi Gray, a species so far known only from caves. Updated distribution maps are presented. Additionally, I present novel morphological data for Wandella using light and scanning electron microscopy. The cephalothorax, spinning organs, genitalia and appendages of some species are illustrated in detail. I report the presence of a putative claw extensor muscle in the male palpal cymbium, and describe interesting modifications in the clypeal region of adult males. The phylogenetic significance of these characters is briefly discussed.