Implications of local knowledge of the ecology of a wild super sweetener for its domestication and commercialization in West and Central Africa

Despite its local use as a fiber and international trade in thaumatin, the intensely sweet protein derived from its fruit, little ecological information aboutThaumatococcus daniellii (Benn.) Benth. is in the public domain. Here, we combine systematic studies of the local knowledge of plant collectors and cultivators in Ghana with a thorough evaluation of the plant’s natural distribution in order to explore possibilities for increasing the contribution that it makes to sustaining rural livelihoods in West and Central Africa. The natural range goes well beyond where commercial collection and cultivation have been previously reported. Local knowledge was found to be detailed and explanatory. Its acquisition has refined our understanding of the ecology of the plant, although some significant gaps remain, particularly with respect to pollination. The market for thaumatin is ripe for expansion, and the plant has untapped potential as an intercrop for rubber and cocoa. Further domestication needs to be accompanied by consideration of impacts on the livelihoods of those who presently collect fruit from the wild, and of opportunities for increasing the value that accrues within Africa through the development of local processing capacity.     

Species diversity reduces invasion success in pathogen‐regulated communities

The loss of natural enemies is thought to explain why certain invasive species are so spectacularly successful in their introduced range. However, if losing natural enemies leads to unregulated population growth, this implies that native species are themselves normally subject to natural enemy regulation. One possible widespread mechanism of natural enemy regulation is negative soil feedbacks, in which resident species growing on home soils are disadvantaged because of a build‐up of species‐specific soil pathogens. Here we construct simple models in which pathogens cause resident species to suffer reduced competitive ability on home soils and consider the consequences of such pathogen regulation for potential invading species. We show that the probability of successful invasion and its timescale depend strongly on the competitive ability of the invader on resident soils, but are unaffected by whether or not the invader also suffers reduced competitive ability on home soils (i.e. pathogen regulation). This is because, at the start of an invasion, the invader is rare and hence mostly encounters resident soils. However, the lack of pathogen regulation does allow the invader to achieve an unusually high population density. We also show that increasing resident species diversity in a pathogen‐regulated community increases invasion resistance by reducing the frequency of home‐site encounters. Diverse communities are more resistant to invasion than monocultures of the component species: they preclude a greater range of potential invaders, slow the timescale of invasion and reduce invader population size. Thus, widespread pathogen regulation of resident species is a potential explanation for the empirical observation that diverse communities are more invasion resistant.     

Interspecific genetics of speciation phenotypes: song and preference coevolution in Hawaiian crickets

Understanding the genetic architecture of traits involved in premating isolation between recently diverged lineages can provide valuable insight regarding the mode and tempo of speciation. The repeated coevolution of male courtship song and female preference across the species radiation of Laupala crickets presents an unusual opportunity to compare the genetic basis of divergence across independent evolutionary histories. Previous studies of one pair of species revealed a polygenic basis (including a significant X chromosome contribution) to quantitative differences in male song and female acoustic preference. Here, we studied interspecific crosses between two phenotypically less-diverged species that represents a phylogenetically independent occurrence of intersexual signalling evolution. We found patterns consistent with an additive polygenic basis to differentiation in both song and preference (n(E) = 5.3 and 5.1 genetic factors, respectively), and estimate a moderate contribution of the X chromosome (7.6%) of similar magnitude to that observed for Laupala species with nearly twice the phenotypic divergence. Together, these findings suggest a similar genetic architecture underlying the repeated evolution of sexual characters in this genus and provide a counterexample to prevailing theory predicting an association between early lineage divergence and sex-linked 'major genes'.     

Kidney function after renal arterial embolism

Seven patients with atrial fibrillation had acute unilateral renal pain associated with suppression of function in the affected kidney. This was ascribed to renal embolism. Arteriography performed in four patients showed abnormalities in the renal arterial tree in three, though thrombus in a main artery was present in only one.Considerable function returned spontaneously to the affected kidney in six patients as judged by intravenous pyelography or renography. In two patients the sole functioning kidney was affected, leading to acute oliguric renal failure, but renal function recovered in each case. The routine use of anticoagulants in persistent atrial fibrillation is justified by such cases.     

Germination of the conidia of Peziza ostracoderma

Conidia ofPeziza ostracoderma Korf, washed by centrifugation and decantation, germinated in a high percentage in glass-distilled water and various nutrient solutions. They also germinated on a wide variety of agar media and in citratephosphate buffers from pH 3 through 8. The conidia first swell to twice their original size, and then emit one cylindrical germ tube. The cardinal temperatures for germination were: minimum, below 3° C; optimum, 20°–33° C; maximum, between 38° and 42° C. A liquid film of water was required for germination.