6 resultados para mating compatibility

em CentAUR: Central Archive University of Reading - UK


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Poly(vinyl ether) gels SLURPS (Superior Liquid Uptake Resin for Polymer-supported synthesis) with low cross-linking levels have been synthesized for the first time in beaded form using a non-aqueous inverse suspension polymerisation approach. The synthetic protocol was optimized with regards to several parameters including reactions conditions, type and concentration of suspension stabilizer and controlled low temperature addition of co-initiator. Particle size measurements confirm the production of beads with average diameters of 700e950 mm. Optimization of the monomer composition of the poly (vinyl ether) gels resulted in a novel beaded polymer support with considerably improved as well as unique swelling characteristics in solvents ranging from hexane to water. The synthetic utility of the new gel was confirmed by carrying out a set of transformations with complete conversion leading to a useful amino and hydroxy terminated solid-phase precursor resin. Reaction progress could be monitored easily by 1H and 13C gel-phase NMR.

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Both the EU’s Renewable Energy Directive (RED) and Article 7a of its Fuel Quality Directive (FQD) seek to reduce greenhouse gas (GHG) emissions from transport fuels. The RED mandates a 10% share of renewable energy in transport fuels by 2020, whilst the FQD requires a 6% reduction in GHG emissions (from a 2010 base) by the same date. In practice, it will mainly be biofuels that economic operators will use to meet these requirements, but the different approaches can lead to either the RED, or the FQD, acting as the binding constraint. A common set of environmental sustainability criteria apply to biofuels under both the RED and the FQD. In particular, biofuels have to demonstrate a 35% (later increasing to 50/60%) saving in life-cycle GHG emissions. This could be problematic in the World Trade Organization (WTO), as a non-compliant biofuel with a 34% emissions saving would probably be judged to be ‘like’ a compliant biofuel. A more economically rational way to reduce GHG emissions, and one that might attract greater public support, would be for the RED to reward emission reductions along the lines of the FQD. Moreover, this modification would probably make the provisions more acceptable in the WTO, as there would be a clearer link between policy measures and the objective of reductions in GHG emissions; and the combination of the revised RED and the FQD would lessen the commercial incentive to import biofuels with modest GHG emission savings, and thus reduce the risk of trade tension.

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Perception and action are tightly linked: objects may be perceived not only in terms of visual features, but also in terms of possibilities for action. Previous studies showed that when a centrally located object has a salient graspable feature (e.g., a handle), it facilitates motor responses corresponding with the feature's position. However, such so-called affordance effects have been criticized as resulting from spatial compatibility effects, due to the visual asymmetry created by the graspable feature, irrespective of any affordances. In order to dissociate between affordance and spatial compatibility effects, we asked participants to perform a simple reaction-time task to typically graspable and non-graspable objects with similar visual features (e.g., lollipop and stop sign). Responses were measured using either electromyography (EMG) on proximal arm muscles during reaching-like movements, or with finger key-presses. In both EMG and button press measurements, participants responded faster when the object was either presented in the same location as the responding hand, or was affordable, resulting in significant and independent spatial compatibility and affordance effects, but no interaction. Furthermore, while the spatial compatibility effect was present from the earliest stages of movement preparation and throughout the different stages of movement execution, the affordance effect was restricted to the early stages of movement execution. Finally, we tested a small group of unilateral arm amputees using EMG, and found residual spatial compatibility but no affordance, suggesting that spatial compatibility effects do not necessarily rely on individuals’ available affordances. Our results show dissociation between affordance and spatial compatibility effects, and suggest that rather than evoking the specific motor action most suitable for interaction with the viewed object, graspable objects prompt the motor system in a general, body-part independent fashion

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Heterosis refers to the phenomenon in which an F1 hybrid exhibits enhanced growth or agronomic performance. However, previous theoretical studies on heterosis have been based on bi-parental segregating populations instead of F1 hybrids. To understand the genetic basis of heterosis, here we used a subset of F1 hybrids, named a partial North Carolina II design, to perform association mapping for dependent variables: original trait value, general combining ability (GCA), specific combining ability (SCA) and mid-parental heterosis (MPH). Our models jointly fitted all the additive, dominance and epistatic effects. The analyses resulted in several important findings: 1) Main components are additive and additive-by-additive effects for GCA and dominance-related effects for SCA and MPH, and additive-by-dominant effect for MPH was partly identified as additive effect; 2) the ranking of factors affecting heterosis was dominance > dominance-by-dominance > over-dominance > complete dominance; and 3) increasing the proportion of F1 hybrids in the population could significantly increase the power to detect dominance-related effects, and slightly reduce the power to detect additive and additive-by-additive effects. Analyses of cotton and rapeseed datasets showed that more additive-by-additive QTL were detected from GCA than from trait phenotype, and fewer QTL were from MPH than from other dependent variables.

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Female aggregation and male territoriality are considered to be hallmarks of polygynous mating systems. The development of genetic parentage assignment has called into question the accuracy of behavioral traits in predicting true mating systems. In this study we use 14 microsatellite markers to explore the mating system of one of the most behaviorally polygynous species, the California sea lion (Zalophus californianus). We sampled a total of 158 female-pup pairs and 99 territorial males across two breeding rookeries (San Jorge and Los Islotes) in the Gulf of California, Mexico. Fathers could be identified for 30% of pups sampled at San Jorge across three breeding seasons and 15% of sampled pups at Los Islotes across two breeding seasons. Analysis of paternal relatedness between the pups for which no fathers were identified (sampled over four breeding seasons at San Jorge and two at Los Islotes) revealed that few pups were likely to share a father. Thirty-one percent of the sampled males on San Jorge and 15% of the sampled males on Los Islotes were assigned at least one paternity. With one exception, no male was identified as the father of more than two pups. Furthermore, at Los Islotes rookery there were significantly fewer pups assigned paternity than expected given the pool of sampled males (p<0.0001). Overall, we found considerably lower variation in male reproductive success than expected in a species that exhibits behavior associated with strongly polygynous mating. Low variation in male reproductive success may result from heightened mobility among receptive females in the Gulf of California, which reduces the ability of males to monopolize groups of females. Our results raise important questions regarding the adaptive role of territoriality and the potential for alternative mating tactics in this species.