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The Réunion grey white-eye, Zosterops borbonicus, a passerine bird endemic to Réunion Island in the Mascarene archipelago, represents an extreme case of microgeographical plumage colour variation in birds, with four distinct colour forms occupying different parts of this small island (2512 km(2)). To understand whether such population differentiation may reflect low levels of dispersal and gene flow at a very small spatial scale, we examined population structure and gene flow by analysing variation at 11 microsatellite loci among four geographically close localities (<26 km apart) sampled within the distribution range of one of the colour forms, the brown-headed brown form. Our results revealed levels of genetic differentiation that are exceptionally high for birds at such a small spatial scale. This strong population structure appears to reflect low levels of historical and contemporary gene flow among populations, unless very close geographically (<10 km). Thus, we suggest that the Réunion grey white-eye shows an extremely reduced propensity to disperse, which is likely to be related to behavioural processes.

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Feathers are essential for avian thermoregulation, communication or flight and a reduction of plumage condition may alter these functions and reduce individual fitness. Recently, descriptive studies provided evidence that birds carry feather-degrading bacteria on their plumage that have the ability to degrade feathers rapidly under laboratory conditions. If such bacteria reduce avian fitness, natural selection should favour the evolution of anti-bacterial defences to limit the effects of these detrimental microorganisms. Preening behaviour and associated preen gland secretions have been proposed as the main factor used by birds to limit feather-degrading bacterial growth and some recent in vitro studies provided evidence that uropygial oil inhibited the growth of some keratinolytic strains in passerines. However, preen oil antimicrobial properties remained to be experimentally tested in vivo. We conducted an experiment with mallards (Anas platyrhynchos) onto which we fixed a removable mechanism that blocked access to the uropygial gland in a first group of mallards, whilst birds in a second group had the same removable mechanism but access to their gland and a third group of birds had normal access to their gland. We found no significant effect of our treatment on total and feather-degrading bacterial loads. Three hypotheses may explain the discrepancy between our results and previous in vitro studies. First, in vitro studies may have over-estimated the bactericidal properties of the preen oil. Second, preen gland deprivation may have affected only a small portion of the feather-degrading bacterial community. Third, ducks and passerine oils might have different bactericidal properties.

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An integrated system of a microreformer and a carrier allowing for syngas generation from liquefied petroleum gas (LPG) for micro-SOFC application is discussed. The microreformer with an overall size of 12.7 mm × 12.7 mm × 1.9 mm is fabricated with micro-electro-mechanical system (MEMS) technologies. As a catalyst, a special foam-like material made from ceria-zirconia nanoparticles doped with rhodium is used to fill the reformer cavity of 58.5 mm(3). The microreformer is fixed onto a microfabricated structure with built-in fluidic channels and integrated heaters, the so-called functional carrier. It allows for thermal decoupling of the cold inlet gas and the hot fuel processing zone. Two methods for heating the microreformer are compared in this study: a) heating in an external furnace and b) heating with the two built-in heaters on the functional carrier. With both methods, high butane conversion rates of 74%-85% are obtained at around 550 °C. In addition, high hydrogen and carbon monoxide yields and selectivities are achieved. The results confirm those from classical lab reformers built without MEMS technology (N. Hotz et al., Chem. Eng. Sci., 2008, 63, 5193; N. Hotz et al., Appl. Catal., B, 2007, 73, 336). The material combinations and processing techniques enable syngas production with the present MEMS based microreformer with high performance for temperatures up to 700 °C. The functional carrier is the basis for a new platform, which can integrate the micro-SOFC membranes and the gas processing unit as subsystem of an entire micro-SOFC system.

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The differential allocation hypothesis predicts that females modify their investment in a breeding attempt according to its reproductive value. One prediction of this hypothesis is that females will increase reproductive investment when mated to high-quality males. In birds, it was shown that females can modulate pre-hatch reproductive investment by manipulating egg and clutch sizes and/or the concentrations of egg internal compounds according to paternal attractiveness. However, the differential allocation of immune factors has seldom been considered, particularly with an experimental approach. The carotenoid-based ornaments can function as reliable signals of quality, indicating better immunity or ability to resist parasites. Thus, numerous studies show that females use the expression of carotenoid-based colour when choosing mates; but the influence of this paternal coloration on maternal investment decisions has seldom been considered and has only been experimentally studied with artificial manipulation of male coloration. Here, we used dietary carotenoid provisioning to manipulate male mallard (Anas platyrhynchos) bill coloration, a sexually selected trait, and followed female investment. We show that an increase of male bill coloration positively influenced egg mass and albumen lysozyme concentration. By contrast, yolk carotenoid concentration was not affected by paternal ornamentation. Maternal decisions highlighted in this study may influence chick survival and compel males to maintain carotenoid-based coloration from the mate-choice period until egg-laying has been finished.

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AIMS: To characterize a new feather-degrading bacterium. METHODS AND RESULTS: The strain kr10 producing a high keratinolytic activity when cultured on native feather broth was identified as Microbacterium sp., based on phenotypical characteristics and 16S rDNA sequence. The bacterium presented optimum growth and feather-degrading activity at pH 7.0 and 30 degrees C. Complete feather degradation was achieved during cultivation. The keratinase was partially purified by gel filtration chromatography. It was optimally active at pH 7.0 and 55 degrees C. The enzyme was inhibited by 1,10-phenanthroline, EDTA, p-chloromercuribenzoic acid, 2-mercaptoethanol and metal ions like Hg(2+), Cu(2+) and Zn(2+). SIGNIFICANCE AND IMPACT OF THE STUDY: A new Microbacterium sp. strain was characterized presenting high feather-degrading activity, which appears to be associated to a metalloprotease-type keratinase. This micro-organism has enormous potential for use in biotechnological processes involving keratin hydrolysis.

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The aim of this study was to determine the diversity of cultivable bacteria able to degrade feathers and present in soil under temperate climate. We obtained 33 isolates from soil samples, which clustered in 13 ARDRA groups. These isolates were able to grow on solid medium with pigeon feathers as sole carbon and nitrogen source. One representative isolate of each ARDRA group was selected for identification and feather degradation tests. The phylogenetic analysis of 16S rDNA gene fragments revealed that only 4 isolates were gram positives. Two other isolates belonged to the Cytophaga-Flavobacterium group, and the remaining to Proteobacteria. High keratinolysis activity was found for strains related to Bacillus, Cytophagales, Actinomycetales, and Proteobacteria. The 13 selected strains showed variable efficiency in degrading whole feathers and 5 strains were able to degrade maximum 40% to 98% of the whole feathers. After 4 weeks incubation, five strains grown on milled feathers produced more than 0.5 U keratinase per mL. Keratinase activities across the 13 strains were positively correlated with the percentage of feather fragmentation and protein concentration.

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The coevolution of parental investment and offspring solicitation is driven by partly different evolutionary interests of genes expressed in parents and their offspring. In species with biparental care, the outcome of this conflict may be influenced by the sexual conflict over parental investment. Models for the resolution of such family conflicts have made so far untested assumptions about genetic variation and covariation in the parental resource provisioning response and the level of offspring solicitation. Using a combination of cross-fostering and begging playback experiments, we show that, in the great tit (Parus major), (i) the begging call intensity of nestlings depends on their common origin, suggesting genetic variation for this begging display, (ii) only mothers respond to begging calls by increased food provisioning, and (iii) the size of the parental response is positively related to the begging call intensity of nestlings in the maternal but not paternal line. This study indicates that genetic covariation, its differential expression in the maternal and paternal lines and/or early environmental and parental effects need to be taken into account when predicting the phenotypic outcome of the conflict over investment between genes expressed in each parent and the offspring.

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Dispersal patterns of organisms are a fundamental aspect of their ecology, modifying the genetic and social structure of local populations. Parasites reduce the reproductive success and survival of hosts and thereby exert selection pressure on host life-history traits, possibly affecting host dispersal. Here we test experimentally whether infestation by hen fleas, Ceratophyllus gallinae, affects sex-related recruitment of great tit, Parus major, fledglings. Using sex-specific DNA markers, we show that flea infestation led to a higher proportion of male fledglings recruiting in the local population in one year. In infested broods, the proportion of male recruits increased with brood size over a three year period, whereas the proportion of male recruits from uninfested broods decreased with brood size. Natal dispersal distances of recruits from infested nests were shorter than those from uninfested nests. To our knowledge, this study provides the first evidence for parasite-mediated host natal dispersal and local recruitment in relation to sex. Current theory needs to consider parasites as potentially important factors shaping life-history traits associated with host dispersal.

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Young mammals are unable to mount an efficient immune response against invading pathogens. Until their immune system is mature mothers transmit to their young immunological compounds during lactation. Given that genetic and foster mothers can assume this protective role, we propose that young mammals may gain immunological benefits by suckling more than one nursing female, a behaviour referred to as "allosuckling". This hypothesis has so far not been considered as a potential explanation for the propensity of young mammals to suckle foster mothers. However, pathogen transmission through milk during allosuckling may reduce the immunological net benefit that young gain, and furthermore allosuckling may increase pathogen transmission between foster and genetic mothers implying costs of allosuckling for all participants. Here, we develop the immunological function of allosuckling hypothesis (IFA) as a potential explanation for intra-and interspecific variation in allosuckling frequency. We present published experimental evidence for the assumption that immunological benefits of allosuckling depend on the immunological status of the offspring, the foster and the genetic mothers. Finally, we give predictions arising from the IFA hypothesis and propose that the IFA may provide a new explanation as to why neonates suckle various females and why foster females often refuse to nurse nonoffspring.

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The evolutionary conflict over the amount of resources transferred between a parent and its offspring may be resolved by honest signalling of 'need' by offspring and parental investment in relation to signalling level. In birds, biparental care is the norm and evidence that male and female parents differ in their investment pattern in individual offspring is growing. In an experiment on great tits, Parus major, we investigated how and why parents differ in food allocation when responding to similar chick signals, which supposedly uniquely reflect the chick's nutritional condition. Nestling hunger level was manipulated by food deprivation and hand-feeding. Subsequent filming revealed that parents fed from significantly different locations on the nest and thereby forced chicks to choose between them when competing for favourable positions. Deprived nestlings approached, and fed ones retreated (or were displaced by siblings) from, positions near the female. No such behaviour was observed towards the male. Females allocated more feeds than males to the food-deprived nestlings. The results are discussed in terms of nestling competition for access to 'begging patches'. By varying their 'begging patch' value, parents may exploit competitive inter-sibling dynamics to influence the outcome of competition among chick phenotypes (e.g. 'need', size, sex). Parent birds may thereby exert considerable control over the information content of chick begging behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

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