Summary1. The management of both desirable and undesirable species requires an understanding of the factors determining their distribution. Quantitative distribution models offer simple methods for formulating the species-habitat link and the means not only for predicting where species should occur, but also for understanding the factors involved. Generalized linear modelling, in particular, links the incidence of species to habitat variables, and has increasingly formed the backbone of the modelling approaches used. New 'data technologies', such as remote sensing and geographical information systems, have further broadened these modelling applications to almost any ecological system and any species for which there are distribution data. 2. Many previous approaches have aimed to identify the most parsimonious model with the best suite of predictors, selected on the basis of null hypothesis testing. However, information-theoretic approaches based on Akaike's information criterion allow the selection of a best approximating model or a subset of models from a set of candidates. Information-theoretic approaches require a deeper understanding of the biology of the system modelled and may well become an improved paradigm for species distribution modelling. 3. Synthesis and applications . This special profile of six papers demonstrates the development in methodology used in species distribution modelling. The papers show how information-theoretic approaches can be coupled with emerging data technologies to address issues of conservation significance. With conservation biology and applied ecology at the forefront of many of the basic science developments so far, we expect these methods to pervade other areas of ecological research more fully in future.

2005. Distribution of selected macroinvertebrates in a mosaic of temporary and permanent freshwater ponds as explained by autologistic models. Á/ Ecography 28: 355 Á/362.We investigated the aquatic macroinvertebrate fauna of 76 ponds and small pools in an urban fringe landscape, and related the presence of ten species to measures of water permanence, pond area and environmental conditions using logistic models. The incidence of all the species was strongly associated with variation in hydroperiod, but patterns were more variable with the other explanatory variables. To determine whether the presence of a species at neighbouring ponds increased its probability of occurance at a pond we constructed a series of autologistic models, that differed from the aspatial logistic model in that they included a spatial autocovariate in the predictor terms. The improvement of model fit on inclusion of this autocovariate, measured as the decline in deviance compared to the aspatial models, was determined across a range of lag distances. In seven of the ten species, the autologistic models explained the incidence of the species amongst the ponds better than the aspatial models. Spatial effects were typically over short distances ( B/200 m) before declining, but in two species appeared to reach an asymptote, and we propose that variation in dispersal ability is the most likely factor producing these spatial effects. We conclude that it is essential that some measure of spatial autocorrelation is considered when evaluating the distribution of aquatic macroinvertebrates at small or medium scales. R. A. Sanderson (r.a.sanderson@newcastle.ac.uk), M. D. Eyre and S. P. Rushton, Inst. for Research in Environment and Sustainability, Devonshire Bldg, Univ. of Newcastle, Newcastle upon Tyne, UK NE1 7RU.

Owing to its catadromous lifestyle, the Chinese mitten crab, Eriocheir sinensis, allows comparison between a coastal and an inland biological invasion of the same species. Information about the distribution of this species in the United Kingdom has been collected from sightings made by governmental agencies, The Natural History Museum (London) collection, literature, and from the general public. This information indicated that the range of the species has expanded since the species' arrival in 1973. The spread has been most marked along the east coast northwards to the river Tyne, on the south coast westwards to the river Teign. The expansion range was quantified and compared using geographic information software, and then compared to recorded spread in Europe. Mitten crabs dispersed along the coast at an average rate of 78 km per year , with a recent sharp increase to 448 km per year (1997)(1998)(1999). These values are comparable with the historic outbreak in continental Europe where the average rate of dispersion along the Baltic Sea coast (1928)(1929)(1930)(1931)(1932)(1933)(1934)(1935) was 416 km per year. Comparable figures for the North Sea coast were 75 km per year with a peak of 168 km per year in 1927-1937. The upstream spread along rivers in the United Kingdom was 16 km per year in 1973-1998 with a marked increase since 1995 to 49 km per year (1995)(1996)(1997)(1998). These data, in combination with population data published for the river Thames, indicate that the population has been increasing since the early 1990s, causing further range expansion into previously uninvaded river systems. The comparison of the spreading behaviour of the ongoing invasion in the United Kingdom with the historic invasion in northern Europe suggests that E. sinensis in future has the potential to establish itself in all major UK estuaries.

Summary 1.The global need for agricultural production has never been greater. Nor has it ever been more complex due to the needs to balance global food security, optimum production, technological innovation, the preservation of environmental functions and the protection of biodiversity. The role of ecologists in finding this balance is pivotal. 2.In support of this role, ecologists now have very substantial experience of agricultural systems. We can understand, recognize and sometimes predict, at least qualitatively, the effects of pesticide applications, fertilizer use, drainage, crop choices and habitat modifications on farmland organisms, agro-ecosystems or other ecosystems influenced by agricultural land. 3. In instances of greater uncertainty, for example under changing climates, where environmental stresses on ecosystems are interactive, and where ecosystem management or restoration must adapt to new technologies, the investigative skills and experience of ecologists are even more crucial in problem solving. 4. There are, nevertheless, contrasting examples of good and bad practice in knowledgetransfer between ecologists and the communities who need our knowledge. The UK farm-scale evaluations of genetically modified crops, for example, involved ecologists at all stages from design and data collection to advocating policy. By contrast, many European agri-environment projects appear to have been developed and evaluated with only modest ecological advice. We advocate fuller involvement of ecologists in the development and evaluation of the European Union Common Agricultural Policy. 5. This special profile of seven agriculturally related papers illustrates effectively the array of approaches used by applied ecologists in addressing agricultural questions: modelling, meta-analysis, surveys, transect studies, classical experiments, seedbank assays and process studies based on modern ecological methods. With over 20% of recent papers in the Journal of Applied Ecology reflecting agricultural issues, agro-ecology continues to represent one of the pre-eminent areas of applied ecology that is unlikely to diminish in importance.

No abstract

Infections by Campylobacter spp. are a major cause of gastrointestinal disease in the United Kingdom. Most cases are associated with the consumption of chicken that has become contaminated during production. We investigated the epidemiology of Campylobacter spp. in chickens in a 3-year longitudinal study of flocks reared on 30 farms in the United Kingdom. We used Generalized Linear Mixed Effect Models (GLMM) to investigate putative risk factors associated with incidence and prevalence of flock infection arising from farm and flock management and local environmental conditions during rearing. We used survival analysis to investigate infection events and associated risk factors over the course of the study using two marginal models - the independent increment approach, which assumed that individual infection events were independent; and a conditional approach, which assumed that events were conditional on those preceding. Models of flock prevalence were highly overdispersed suggesting that infection within flocks was aggregated. The key predictors of flock infection identified from the GLMM analyses were mean temperature and mean rainfall in the month of slaughter and also the presence of natural ventilation. Mean temperature in the month of slaughter was also a significant predictor of flock infection, although the analyses suggested that the risk in flocks increased in a unimodal way in relation to temperature, peaking at 12 degrees C. The extent of pad burn was also identified as a predictor in these analyses. We conclude that predicting prevalence within flocks with linear modelling approaches is likely to be difficult, but that it may be possible to predict when flocks are at risk of Campylobacter infection. This is a key first step in managing disease and reducing the risks posed to the human food chain.

SUMMARYIn September 2006, the 7-valent pneumococcal conjugate vaccine (PCV7) was added to the UK immunization programme. We aimed to evaluate the impact of PCV7 on the incidence of all-cause community-acquired pneumonia (CAP) in children. A prospective survey was undertaken in 2008–2009 at 11 hospitals in North East England of children aged 0–16 years with radiologically confirmed pneumonia. Data were compared to those from a similar survey undertaken in the same hospitals in 2001–2002. A total of 542 children were enrolled, of which 74% were aged <5 years. PCV7 uptake was 90·7%. The incidence of pneumonia was 11·8/10 000 [95% confidence interval (CI) 10·9–12·9], and the hospitalization rate was 9·9/10 000 (95% CI 9·0–10·9). Compared to 2001, there was a 19% (95% CI 8–29) reduction in the rate of CAP in those aged <5 years, and in those <2 years a 33·1% (95% CI 20–45) reduction in the incidence of CAP and 38·1% (95% CI 24–50) reduction in hospitalization rates. However, for those unvaccinated aged ⩾5 years, there was no difference in the incidence of CAP and hospitalization rate between both surveys. Since 2001, the overall reduction in incidence was 17·7% (95% CI 8–26) and for hospitalization 18·5% (95% CI 8–28). For the <5 years age group there was a lower incidence of CAP in PCV7-vaccinated children (25·2/10 000, 95% CI 22·6–28·2) than in those that were not vaccinated (37·4/10 000, 95% CI 29·2–47·1). In conclusion, PCV7 has reduced both incidence and rate of hospitalization of pneumonia in children, particularly in the <2 years age group.

202 running-water sites in the catchment of the River Rede, a tributary of the River Tyne in northern England, were sampled for invertebrates in 1990. The distributions of water beetle species were investigated using logistic regression with several environmental factors. A number of site structure characteristics were assessed and the presence or absence of silt (as peat or clay) was found to be the most important single variable. Shingle, pebbles, cobbles, boulders and the amount of vegetation present were less important substrate variables. The distance from stream source reflected substrate structure and site gradient was a poor determinant of species distribution. A composite variable, termed the exposure index, was derived from all the site structure characteristics using an ordination and was found to be useful in explaining species distribution. Water pH also affected distributions considerably. Two variable analyses using the exposure index and water pH gave the best explanation of species distribution. The two variables used together were a reflection of productivity and disturbance, the two main components of habitat templates and strategy theory. The distribution of water beetle species in the Rede catchment was a product of these factors, which, in turn, were a product of the geography of the catchment.