Biological invasions have major economic and environmental impacts on agriculture, epidemiology and conservation, yet our current understanding of the processes involved is hampered by studying causal drivers in isolation and largely ignoring rapid evolution. Here, we aim to use experimental populations of microbes, combined with a related theoretical and modeling agenda, to study: 1) the effect of independent, and combined, manipulation of disturbance and diversity on invasion success; and 2) the role of pre-adaptation to disturbance regimes in mediating invasion resistance. This integrated theoretical-empirical approach will greatly improve our conceptual understanding of the role disturbance and diversity play in mediating invasion.

Why and how animals cooperate with each other remains a fascinating challenge to explain. We know that individuals within families or that regularly interact with each other are far more likely to gain reciprocal benefits from cooperating with each other. However, there are many examples across the animal kingdom where these conditions don't hold and where cooperation is observed in situations in which it isn't predicted. We have recently uncovered such an example in our studies of the social responses of fruitflies. They don't live in familial or social groups, which predicts that they should be very unlikely to express socially cooperative behaviour. Nevertheless, we have found that females have remarkably fine-tuned responses to their social environments. For example, when they detect the presence of other females they very rapidly increase their rate of egg laying and alter their sexual receptivity. Eggs laid by groups of females that meet on food substrates females are laid together in clumps together with those of other females and, unexpectedly, these eggs seem to benefit from the cooperative protection offered by the eggs of other females. Laying eggs in communal batches seems to be beneficial because eggs are laid with an antimicrobial and anticannibalism 'coating': this diffuses and prevents spoilage of the substrate on which the eggs are laid, and prevents eggs from being eaten by any larvae that are present. The defensive coating protects batches of eggs (and resulting larvae) on a food patch. However, the production of these antimicrobial and anticannibalistic chemicals is energetically costly and potentially open to exploitation by others. This is because, if some individuals lay 'defenceless' eggs next to those with a strong antimicrobial coat or with effective anti-cannibalism defences, they can benefit without paying costs and hence can 'free-ride' the system. The explanation for what prevents most individuals from cheating like this resides in a powerful body of theory concerning 'public goods'. Key to the explanation is whether the benefits of producing public goods (i.e. the antimicrobial and anti-cannibalism defences) are 'non linear', for example if the only way everyone can benefit is if a threshold number of cooperating individuals pitch in. The aim of our project is to measure how and why cooperation over public goods occurs in our test system, and hence test the predictions of this important theory. Using the power of the fruitfly system, we can do this by experimentally manipulating the whole system, from the sensory inputs, to the production of public goods themselves, to the outcome in terms of the reproductive output of individual females. We will investigate: (1) The nature of benefits to females from responding to social environments through the production of public goods such as antimicrobial and anti-cannibalistic chemicals. (2) The shape of the relationship between the production of public goods and fitness. (3) The gene regulatory mechanisms underlying the production of socially responsive public goods. The results of this programme will provide a significant step forward in our understanding of fundamental components of social biology. These principles will have broad impact across taxa and will help to show us how and why we behave as we do.

Here we detail a multidisciplinary exploratory study bringing together expertise in disease ecology/epidemiology, biomedicine, microbiology, environmental science, genomics and mathematical modelling to study the interactions between bacteria causing human disease (pathogens) and free-living helminths (nematode worms), both commonly found co-occurring in the soil. Previous work has shown that free-living helminths harbour a range of pathogens and that these could be transmitted to humans by accidental ingestion of free-living helminths or via parasitic helminths infected with human pathogens; termed helminth vectors. As such, our overall aim is to bring together experts from different fields to adopt a unique approach to experimentally test and monitor the association between pathogens and free-living helminths (parasitic and non-parasitic). This interaction may show a previously undiscovered mechanism of pathogen persistence and transmission in the environment, which in turn may lead to increased persistence and survival of pathogens in the soil with obvious implications for human health. In this study we will ascertain the advantages conferred to pathogens by associating with helminths. We ask questions such as 'does association of a pathogen with a worm protect the pathogen from environmental conditions that it otherwise would not survive, or offer protection against food sanitizers?' A natural progression is to then ask 'how does helminth vectoring alter persistence of the pathogen in the host population?' We will use model systems for our experiments because of their applicability to other systems and also for ease of work in terms of published techniques as well as availability of a range of phenotypic mutants useful to testing our hypotheses. We will use the free-living non-parasitic nematode Caenorhabditis elegans, because of its extensive use in genetic studies leading to a proliferation of established techniques. We will also use a parasitic helminth; the nematode Heligmosomoides polygyrus, a common parasite of wild mice. The bacteria used in the study will be Salmonella typhimurium and E. coli O157, which both cause severe gastrointestinal infections in humans and are common in the soil. In our study we plan to use a novel monitoring system; that of bioluminescent reporter bacteria. To discover whether these bacteria can be spread to humans and animals by small soil dwelling nematode worms, we will use genetically modified Salmonella and E. coli O157 that express the lux genes so that they are self-bioluminescent. The modified bacteria emit light when they are alive and can therefore be seen within the organism they are infecting, whether that is a worm or a larger organism, such as a mouse, which feeds on the bacteria. This gives us a novel method to study persistence and transmission of the disease causing (pathogenic) bacteria in the environment. This proposal aims to elucidate interactions between pathogenic bacteria, helminths (free-living and parasitic nematode worms), and the environmental conditions they experience and the implications this has for persistence of pathogenic bacteria in the environment and host. We aim to test the hypothesis that free-living helminths can be both environmental reservoirs and vectors of disease causing bacteria, using laboratory experiments, in conjunction with mathematical modelling. We posit that helminth vectors/reservoirs confer advantages to pathogenic bacteria that alter the way in which pathogens persist in the environment and may also alter the ability of these bacteria to cause human disease. The final part of the project will use DNA micro-array technology to investigate whether the bacteria become more infectious when they are carried by nematode worms. Our findings will have important implications for the dynamics and control of pathogens found in the environment, including human enteric pathogens and important livestock infections.

The development of optical fibres led directly to the data communications revolution of the late 20th century and are now impacting many other fields from remote sensing to biomedicine. This impact is growing in part because of rapid advances in active devices for which the fibre serves not merely as a passive waveguide, but as a medium to directly modulate, generate, or otherwise manipulate light. As a result of this versatility, fibres form key components of systems in almost any applications that use light. In parallel with these breakthroughs in photonics, the computer and microelectronics industries has seen exponential growth every 18 months since the 1960's of the performance to price ratio of transistors on CPU and DRAM chips, with commensurate improvements in optoelectronic components such as the visible lasers used in DVD players, and the infrared laser diodes used to generate and modulate light for data communications in optical fibres. The crystalline semiconductors upon which all microelectronics is based, namely silicon, germanium, gallium arsenide and many others, are familiar to almost every scientist and engineer. The advanced technological fields represented by fibre optics that are based on very long, very thin strands of glass and microelectronics based on planar chips fabricated by lithography, are typically integrated to create communication network systems by using intermediate optics and packaging. However, the technology we are developing allows crystalline semiconductor structures made from silicon and germanium directly inside the optical fibre itself. This technique utilises a deposition process similar to that used for modern planar electronic devices and so opens up the possibility for directly combining the light guiding capabilities of optical fibres with the exceptional capabilities of semiconductors for manipulating light and electrons. This suggests that many of the functions currently performed by planar optoelectronics might now be integrated directly inside the fibre itself, and that many new semiconductor devices that cannot be realised in a conventional planar geometry may now become possible. Advanced technological applications demand high performance devices, which in turn require exceptional materials; our efforts focus on the fundamental materials research and development necessary to move this innovation beyond the laboratory to next generation photonic devices and systems.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.