How do misassigned paternities affect the estimation of heritability in the wild?

Studies of birds have recently played an important role in the increasing success of quantitative genetics applied to natural populations. However, these studies mostly base their pedigree relationships on social information, despite the known widespread genetic polygamy in avian species. Here, we study the influence of misassigned paternities, combined with the effect of pedigree size and depth, on the estimation of heritability. First, we compute simulations of a polygenic trait for two levels of heritability (0.1 and 0.4), several extra-pair paternity rates (ranging from 5% to 40%), and varying sample sizes (20, 50 and 100 broods) or pedigree depth (2 or 4 generations). We compare heritability estimates from the social and the genetic pedigree, running a restricted maximum-likelihood 'animal model'. Social pedigree underestimates heritability by an average of 0-17% for 5-20% extra-pair paternities and by up to 18% for 40% extra-pair paternities and a heritability of 0.4. Second, we identifyied extra-pair offspring using microsatellite loci in two populations of blue tits (Parus caeruleus) showing high levels of extra-pair paternities (15% and 25% of extra-pair offspring). We compare heritabilities of tarsus length and body mass estimated with pedigrees of increasing accuracy. These analyses suggest that the bias induced by misassigned paternities on heritability estimation depends on the level of heritability and the rate of paternity error. Typical rates of extra-pair paternities in birds (around 20% of offspring) should result in an underestimation of heritability of less than 15% when estimated over a minimum of 100 broods.     

How do reaction conditions affect the enantiopure synthesis of 2‐substituted‐1,4‐benzodioxane derivatives?

Several biologically active compounds structurally include the enantiopure 2‐substituted‐1,4‐benzodioxane scaffold. The straightforward racemization that affects reactions involving most of the common chemical reactives is thus a crucial issue. The developing of a completely stereo‐controlled synthetic route that does not affect the enantiomeric excess is consequently mandatory. It is also important to set up a reliable chiral HPLC method, able to follow the reaction, and to improve the synthetic performances. Here, we report the chiral investigation of two different synthons, we specifically evaluated the synthetic pathways that could be run in order to afford them, avoiding the racemization processes, which could normally occur in basic conditions. In addition, we developed peculiar chiral HPLC methods in order to resolve the enantiomers, define the enantiomeric excess, and fully characterize these compounds.     

How does pollination mutualism affect the evolution of prior self‐fertilization? A model

The mode of pollination is often neglected regarding the evolution of selfing. Yet the distribution of mating systems seems to depend on the mode of pollination, and pollinators are likely to interfere with selfing evolution, since they can cause strong selective pressures on floral traits. Most selfing species reduce their investment in reproduction, and display smaller flowers, with less nectar and scents (referred to as selfing syndrome). We model the evolution of prior selfing when it affects both the demography of plants and pollinators and the investment of plants in pollination. Including the selfing syndrome in the model allows to predict several outcomes: plants can evolve either toward complete outcrossing, complete selfing, or to a stable mixed‐mating system, even when inbreeding depression is high. We predict that the evolution to high prior selfing could lead to evolutionary suicides, highlighting the importance of merging demography and evolution in models. The consequence of the selfing syndrome on plant–pollinator interactions could be a widespread mechanism driving the evolution of selfing in animal‐pollinated taxa.     

How do surfactants and DTT affect the size, dynamics, activity and growth of soluble lysozyme aggregates?

The early intermediates in the protein aggregation pathway, the elusive soluble aggregates, play a pivotal role in growth and maturation of ordered aggregates such as amyloid fibrils. Blocking the growth of soluble oligomers is an effective strategy to inhibit aggregation. To decipher the molecular mechanisms and develop better strategies to arrest aggregation, it is imperative to understand how the size, molecular dynamics, activity and growth kinetics of soluble aggregates are affected when aggregation is inhibited. With this objective, in the present study we have investigated the influence of additives such as SDS, CTAB (cetyltrimethylammonium bromide) and DTT (dithiothreitol) on the slow aggregation of HEWL (hen eggwhite lysozyme) at pH 12.2. For this purpose, techniques such as steady-state and time-resolved fluorescence anisotropy of covalently labelled dansyl probe, gel-filtration chromatography, estimation of free thiol groups, thioflavin T and ANS (8-anilinonaphthalene-1-sulfonic acid) fluorescence, CD and atomic-force microscopy were employed to monitor the soluble oligomers over a period spanning 30 days. The results of the present study reveal that: (i) the spontaneous formation of soluble aggregates is irreversible and abolishes activity; (ii) the initial growth of aggregates (0-24 h) is promoted by a gradual increase in the exposure of hydrophobic surfaces; (iii) subsequently intermolecular disulfide bonds are critical for the assembly and stability of aggregates; (iv) the tight molecular packing inside large aggregates which contributed to slow (approximately 5 ns) and restricted segmental motion of dansyl probe was clearly loosened up in the presence of additives, enabling fast (1-2 ns) and free motion (unlike DTT, the size of lysozyme complexes with surfactants, was large, due to a conglomeration of proteins and surfactants); (v) the aggregates show reduced helical content compared with native lysozyme, except in the presence of SDS; and (vi) DTT was more potent than SDS/CTAB in arresting the growth of aggregates.     

Composition, antimicrobial and antioxidant activity of the extracts of Eryngium palmatum Pančić and Vis. (Apiaceae)

The chemical composition, antimicrobial and antioxidant activity of Eryngium palmatum, an endemic plant species from the Balkan Peninsula, were investigated. The flavonoids apigenin (9.5±0.3 mg g^?1) and apigenin 7-O-glucoside (2.4±0.1 mg g^?1) were determined in a methanol extract of aerial parts using HPLC analysis. The methanol extract of roots contained catechin (5.0±0.1 mg g^?1), epicatechin (2.9±0.1 mg g^?1), chlorogenic acid (1.6±0.0 mg g^?1), gallic acid (0.9±0.0 mg g^?1) and rosmarinic acid (0.9±0.2 mg g^?1). GC-FID and GCMS analysis of a chloroform extract of aerial parts showed that the main volatile constituents were falcarinol, linoleic acid, hexadecanoic acid and methyl linoleate (comprising 32.6%; 24.4%; 19.9; 13.2% of the volatile fraction, respectively), while octanoic acid, tetradecanol and dodecanol dominated in the chloroform extract of the roots (34.9%; 25.8%; 22.2% of the volatile fraction, respectively). Investigation of antimicrobial activity by broth microdilution showed that the methanol and chloroform extracts of aerial parts and roots exerted a significant effect (MIC 3.5–15.6 μg mL^?1) against tested Gram-positive and Gram-negative bacteria. The methanol extracts of aerial parts or roots exerted moderate ferric reducing antioxidant power, DPPH radical scavenging activity and hydroxyl radical scavenging activity.     

How does habitat structure affect activity and use of space among house mice?

For small mammals that are vulnerable to predation, the protection provided by physical structuring within the habitat is important in determining suitable nest or resting sites but little is known about how different aspects of structure affect use of the habitat more generally. We examined the effects of ground-level structure (open/complex), overhead cover (present/absent) and the distribution of protected nest sites and food (clumped together/scattered) on activity and use of space among house mice, Mus domesticus, in enclosures. Adult pairs were housed in eight habitat types differing in arrangement of nestboxes, bricks and cover sheets, and their location was monitored under infrared light every 0.5 s over 4 h during the dark period. The mice spent much more time within protected nest sites and were more restricted in use of different sites within habitats that had little ground-level structure and no overhead cover. Much wider use was made of structurally complex habitats. Complex ground-level structure had the greatest impact on emergence from protected nest sites and use of space, since mice preferred to stay close to, or on top of, walls and other objects when undisturbed. The influence of overhead cover on normal activity depended on the extent of ground-level structure and origin of the mice, but, when disturbed by an experimenter, mice sheltered under overhead cover or in enclosed nest sites. Preference between nest sites depended on accessibility from under overhead cover and proximity to enclosure walls. We found almost no sex differences in activity or use of space. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.      

How does competition affect the transmission of information?

The use of social information is a prerequisite to the evolution of culture. In humans, social learning allows individuals to aggregate adaptive information and increase the complexity of technology at a level unparalleled in the animal kingdom. However, the potential to use social information is related to the availability of this type of information. Although most cultural evolution experiments assume that social learners are free to use social information, there are many examples of information withholding, particularly in ethnographic studies. In this experiment, we used a computer-based cultural game in which players were faced with a complex task and had the possibility to trade a specific part of their knowledge within their groups. The dynamics of information transmission were studied when competition was within- or exclusively between-groups. Our results show that between-group competition improved the transmission of information, increasing the amount and the quality of information. Further, informational access costs did not prevent social learners from performing better than individual learners, even when between-group competition was absent. Interestingly, between-group competition did not entirely eliminate access costs and did not improve the performance of players as compared with within-group competition. These results suggest that the field of cultural evolution would benefit from a better understanding of the factors that underlie the production and the sharing of information.     

How does climate warming affect plant‐pollinator interactions?

Climate warming affects the phenology, local abundance and large-scale distribution of plants and pollinators. Despite this, there is still limited knowledge of how elevated temperatures affect plant-pollinator mutualisms and how changed availability of mutualistic partners influences the persistence of interacting species. Here we review the evidence of climate warming effects on plants and pollinators and discuss how their interactions may be affected by increased temperatures. The onset of flowering in plants and first appearance dates of pollinators in several cases appear to advance linearly in response to recent temperature increases. Phenological responses to climate warming may therefore occur at parallel magnitudes in plants and pollinators, although considerable variation in responses across species should be expected. Despite the overall similarities in responses, a few studies have shown that climate warming may generate temporal mismatches among the mutualistic partners. Mismatches in pollination interactions are still rarely explored and their demographic consequences are largely unknown. Studies on multi-species plant-pollinator assemblages indicate that the overall structure of pollination networks probably are robust against perturbations caused by climate warming. We suggest potential ways of studying warming-caused mismatches and their consequences for plant-pollinator interactions, and highlight the strengths and limitations of such approaches.     

How does the exosite of rhomboid protease affect substrate processing and inhibition?

Rhomboid proteases constitute a family of intramembrane serine proteases ubiquitous in all forms of life. They differ in many aspects from their soluble counterparts. We applied molecular dynamics (MD) computational approach to address several challenging issues regarding their catalytic mechanism: How does the exosite of GlpG rhomboid protease control the kinetics efficiency of substrate hydrolysis? What is the mechanism of inhibition by the non‐competitive peptidyl aldehyde inhibitors bound to the GlpG rhomboid active site (AS)? What is the underlying mechanism that explains the hypothesis that GlpG rhomboid protease is not adopted for the hydrolysis of short peptides that do not contain a transmembrane domain (TMD)? Two fundamental features of rhomboid catalysis, the enzyme recognition and discrimination of substrates by TMD interactions in the exosite, and the concerted mechanism of non‐covalent pre‐catalytic complex to covalent tetrahedral complex (TC) conversion, provide answers to these mechanistic questions.     

How do pectin methylesterases and their inhibitors affect the spreading of tobamovirus?

After replication in the cytoplasm, viruses spread from the infected cell into the neighboring cells through plasmodesmata, membranous channels embedded by the cell wall. As obligate parasites, viruses have acquired the ability to utilize host factors that unwillingly cooperate for the viral infection process. For example, the viral movement proteins (MP) interacts with the host pectin methylesterase (PME) and both proteins cooperate to sustain the viral spread. However, how and where PMEs interact with MPs and how the PME/MP complexes favor the viral translocation is not well understood. Recently, we demonstrated that the overexpression of PME inhibitors (PMEIs) in tobacco and Arabidopsis plants limits the movement of Tobacco mosaic virus and Turnip vein clearing virus and reduces plant susceptibility to these viruses. Here we discuss how overexpression of PMEI may reduce tobamovirus spreading.     

How do chemical denaturants affect the mechanical folding and unfolding of proteins?

We present the first single-molecule atomic force microscopy study on the effect of chemical denaturants on the mechanical folding/unfolding kinetics of a small protein GB1 (the B1 immunoglobulin-binding domain of protein G from Streptococcus). Upon increasing the concentration of the chemical denaturant guanidinium chloride (GdmCl), we observed a systematic decrease in the mechanical stability of GB1, indicating the softening effect of the chemical denaturant on the mechanical stability of proteins. This mechanical softening effect originates from the reduced free-energy barrier between the folded state and the unfolding transition state, which decreases linearly as a function of the denaturant concentration. Chemical denaturants, however, do not alter the mechanical unfolding pathway or shift the position of the transition state for mechanical unfolding. We also found that the folding rate constant of GB1 is slowed down by GdmCl in mechanical folding experiments. By combining the mechanical folding/unfolding kinetics of GB1 in GdmCl solution, we developed the “mechanical chevron plot” as a general tool to understand how chemical denaturants influence the mechanical folding/unfolding kinetics and free-energy diagram in a quantitative fashion. This study demonstrates great potential in combining chemical denaturation with single-molecule atomic force microscopy techniques to reveal invaluable information on the energy landscape underlying protein folding/unfolding reactions.     

Is the structural and psittacofulvin‐based coloration of wild burrowing parrots Cyanoliseus patagonus condition dependent?

The bright colours of parrots are caused by psittacofulvin pigments, which appear unique to this Order, and by structural colours. We measured red (psittacofulvin), green (mixed) and blue (structural) colours of wild burrowing parrots Cyanoliseus patagonus of northeastern Patagonia, Argentina, and measured nestlings regularly to obtain data on breeding success and nestling growth. As adult feathers are moulted outside the breeding season, adult body condition could not be measured directly during feather growth, and climatic conditions were used as an indirect parameter. The colony of burrowing parrots is surrounded by Monte steppe habitat, the breeding success has been shown to depend strongly on the climatic patterns. The area experienced a drought with very poor breeding success as well as a year of above‐average precipitation during the study period, serving as a natural experiment. We thus analysed the variability of colouration within the population among and within breeding seasons. We observed strong inter‐annual differences in nestling and adult colouration. Nestlings grew blue feathers with lower achromatic brightness during better conditions, and when controlling for year effects, nestlings with higher mass and from more successful families also had blue feathers with lower achromatic brightness. Adult blue feathers showed the same trend, with lower achromatic brightness in the moult following breeding seasons of better conditions. In contrast, during better conditions, adults grew red feathers with higher achromatic brightness and the colour hue was also affected, and the hue of the red region of nestlings varied with the hatching order. The colour of all three regions of nestlings varied between nests, and the colour of the red region of adult males positively correlated with breeding success (clutch size, brood size). In summary, the present data suggest that environmental conditions contribute to variability in both structural and the psittacofulvin‐based colours of wild burrowing parrots.     

How does parental role influence the activity and movements of breeding wolves?

We studied the activity and movements of a male and a female wolf during breeding in the Bieszczady Mountains, Poland. The female was less active and mobile and on average closer to the den than the male. The male was less active and mobile when the pack size was seven compared to a year when the pack consisted only of the breeding pair. We conclude that the roles played by breeding males and females rearing pups influence their activity, and that breeding males in larger packs move less during the nursing period because of help by other pack members.     

How do food quality and larval crowding affect performance of the autumnal moth,Epirrita autumnata?

Outbreak densities of autumnal moth, Epirrita autumnata (Borkhausen) (Lepidoptera: Geometridae), lead to high larval crowding. Phenotypic responses of E. autumnata to larval crowding and to food quality were studied by measuring growth and consumption as well as pupal weight and fecundity. Crowding may trigger increased consumption and faster development to avoid impending food shortage on good quality food. This is suggested by the result that on a good‐quality diet, the growth of crowded larvae was better than that of solitary larvae, though they did not consume more food than solitary larvae. Crowded larvae also completed the last instar earlier than solitary larvae. The fecundity of crowded autumnal moths was not lower than the fecundity of solitarily grown autumnal moths. This may provide conditions for extra rapid population build‐up of E. autumnata. During the population increase phase the crowding effect may facilitate larval performance; however, at peak density the crowding starts to have negative effects on the performance of larvae. On a poor‐quality diet, the performance of crowded and solitary larvae did not differ. The growth of larvae was better on a good‐quality diet than on a poor‐quality diet, due to higher efficiency in food utilization. Larvae feeding on low‐quality diet did not prolong their development time, but pupated at smaller size; this resulted in lower fecundity. A decrease in food quality can be seen as a cue of oncoming food shortage and resource depletion; it may be advantageous to pupate at a smaller size and ensure survival till reproduction, rather than risk prolonging development to achieve larger size and higher fecundity.     

How do elevated levels of testosterone affect the function of the human fallopian tube and fertility?—New insights

Excess testosterone levels affect up to 20% of the female population worldwide and are a key component in the pathogenesis of polycystic ovary syndrome. However, little is known about how excess testosterone affects the function of the human fallopian tube—the site of gamete transport, fertilization, and early embryogenesis. Therefore, this study aimed to characterize alterations caused by long‐term exposure to male testosterone levels. For this purpose, the Fallopian tubes of nine female‐to‐male transsexuals, who had been undergoing testosterone treatment for 1–3 years, were compared with the tubes of 19 cycling patients. In the ampulla, testosterone treatment resulted in extensive luminal accumulations of secretions and cell debris which caused ciliary clumping and luminal blockage. Additionally, the percentage of ciliated cells in the ampulla was significantly increased. Transsexual patients, who had had sexual intercourse before surgery, showed spermatozoa trapped in mucus. Finally, in the isthmus complete luminal collapse occurred. Our results imply that fertility in women with elevated levels of testosterone is altered by tubal luminal obstruction resulting in impaired gamete transport and survival.     

Do hormone‐modulating chemicals impact on reproduction and development of wild amphibians?

Globally, amphibians are undergoing a precipitous decline. At the last estimate in 2004, 32% of the approximately 6000 species were threatened with extinction and 43% were experiencing significant declines. These declines have been linked with a wide range of environmental pressures from habitat loss to climate change, disease and pollution. This review evaluates the evidence that endocrine‐disrupting contaminants (EDCs) – pollutants that affect hormone systems – are impacting on wild amphibians and contributing to population declines. The review is limited to anurans (frogs and toads) as data for effects of EDCs on wild urodeles (salamanders, newts) or caecilians (limbless amphibians) are extremely limited. Evidence from laboratory studies has shown that a wide range of chemicals have the ability to alter hormone systems and affect reproductive development and function in anurans, but for the most part only at concentrations exceeding those normally found in natural environments. Exceptions can be found for exposures to the herbicide atrazine and polychlorinated biphenyls in leopard frogs (Rana pipiens) and perchlorate in African clawed frogs (Xenopus laevis). These contaminants induce feminising effects on the male gonads (including ‘intersex’ – oocytes within testes) at concentrations measured in some aquatic environments. The most extensive data for effects of an EDC in wild amphibian populations are for feminising effects of atrazine on male gonad development in regions across the USA. Even where strong evidence has been provided for feminising effects of EDCs, however, the possible impact of these effects on fertility and breeding outcome has not been established, making inference for effects on populations difficult. Laboratory studies have shown that various chemicals, including perchlorate, polychlorinated biphenyls and bromodiphenylethers, also act as endocrine disrupters through interfering with thyroid‐dependent processes that are fundamental for amphibian metamorphosis. Perchlorate has also been shown to induce these effects in wild anuran populations from perchlorate‐contaminated environments. Overall, the published data available suggest that some health effects observed in wild anuran populations, most notably intersex, likely have a chemical aetiology; however they derive only from very few anuran species and for a few pesticides at field sites in the USA. To understand better the impacts of EDCs on wild anuran populations, as well as other amphibian groups, assessment of fertility in exposed animals are required. Development of non‐destructive biomarkers that are indicative of specific EDC‐effect mechanisms are also needed to allow the study of vulnerable populations. This will help to distinguish the effects of EDCs from other environmental and/or genetic influences on development and reproduction.     

How could preventive therapy affect the prevalence of drug resistance? Causes and consequences

Various forms of preventive and prophylactic antimicrobial therapies have been proposed to combat HIV (e.g. pre-exposure prophylaxis), tuberculosis (e.g. isoniazid preventive therapy) and malaria (e.g. intermittent preventive treatment). However, the potential population-level effects of preventative therapy (PT) on the prevalence of drug resistance are not well understood. PT can directly affect the rate at which resistance is acquired among those receiving PT. It can also indirectly affect resistance by altering the rate at which resistance is acquired through treatment for active disease and by modifying the level of competition between transmission of drug-resistant and drug-sensitive pathogens. We propose a general mathematical model to explore the ways in which PT can affect the long-term prevalence of drug resistance. Depending on the relative contributions of these three mechanisms, we find that increasing the level of coverage of PT may result in increases, decreases or non-monotonic changes in the overall prevalence of drug resistance. These results demonstrate the complexity of the relationship between PT and drug resistance in the population. Care should be taken when predicting population-level changes in drug resistance from small pilot studies of PT or estimates based solely on its direct effects.     

Does multi‐level environmental filtering determine the functional and phylogenetic composition of wild bee species assemblages?

A central goal in ecology is to develop theories that explain the diversity and distribution of species. The evolutionary history of species and their functional traits may provide mechanistic links between community assembly and the environment. Such links may be hierarchically structured such that the strength of environmental filtering decreases in a step‐wise manner from regional conditions through landscape heterogeneity to local habitat conditions. We sampled the wild bee species assemblages in power‐line strips transecting forests in south‐eastern Norway. We used altitude, landscape diversity surrounding sites and plant species composition, together with total plant cover as proxies for regional, landscape and local environmental filters, respectively. The species richness and abundance of wild bees decreased with altitude. The reduction in species richness and abundance was accompanied by a phylogenetic clustering of wild bee individuals. Furthermore, regional filters followed by local filters best explained the structure of the functional species composition. Sites at high altitudes and sites with Ericaceae‐dominated plant communities tended to have larger bees and a higher proportion of social and spring‐emerging bees. When Bombus species were excluded from the analysis, the proportion of pollen specialists increased with the dominance of Ericaceae. Furthermore, we also found that the taxonomic, phylogenetic and functional compositional turnover between sites was higher in the northern region than in the southern part of the study region. Altogether, these results suggest that regional filters drive the species richness and abundance in trait‐groups whereas local filters have more descrete sorting effects. We conclude that the model of multi‐level environmental filters provides a good conceptual model for community ecology. We suggest that future studies should focus on the relationship between the biogeographical history of species and their current distribution, and on the assumption that closely related species do indeed compete more intensely than distantly related species.