Interactions between invasive and native crustaceans: differential functional responses of intraguild predators towards juvenile hetero-specifics

Intraguild predation (IGP) between invasive and native species can lead to species exclusions or co-existence, dependent on the direction and strength of the interaction. Recently, derivation of 'functional responses' has been identified as a means of comparing the community impacts of invasive and native species. Here, we employ a novel use of this functional response methodology to evaluate any IGP asymmetries between the invasive Ponto-Caspian amphipod Echinogammarus ischnus and the North American native Gammarus fasciatus. The direction and magnitude of intraguild predation of adult males on hetero-specific adult females has previously been shown to reverse across a water conductivity gradient. This partially explains field patterns, but does not predict the co-existence of the two species observed in many habitats and locations. Here, we compared intraguild predation by both species on each other's juveniles in high- and low- conductivity water. G. fasciatus has a higher type II functional response towards E. ischnus juveniles compared to the reciprocal interaction. Conductivity did not influence the predation rate on juveniles of either E. ischnus or G. fasciatus. Thus, the male/female IGP advantage to the native G. fasciatus in low conductivity water is compounded by a juvenile IGP asymmetry, which also counteracts the male/female IGP advantage to E. ischnus in high conductivity waters, helping to explain field patterns of exclusion and co-existence. Thus, complex asymmetries in mutual IGP associated with inherent species differences, environmental modulation, and life-history effects can help us understand and predict the population and community level outcomes of species invasions.

Were last glacial climate events simultaneous between Greenland and France? A quantitative comparison using non-tuned chronologies

Several large abrupt climate fluctuations during the last glacial have been recorded in Greenland ice cores and archives from other regions. Often these Dansgaard-Oeschger events are assumed to have been synchronous over wide areas, and then used as tie-points to link chronologies between the proxy archives. However, it has not yet been tested independently whether or not these events were indeed synchronous over large areas. Here, we compare Dansgaard-Oeschger-type events in a well-dated record from southeastern France with those in Greenland ice cores. Instead of assuming simultaneous climate events between both archives, we keep their age models independent. Even these well-dated archives possess large chronological uncertainties that prevent us from inferring synchronous climate events at decadal to multi-centennial time scales. If possible, comparisons between proxy archives should be based on independent, non-tuned time-scales. Copyright (C) 2009 John Wiley & Sons, Ltd.

The Creative Life of Law: Improvisation, Between Tradition and Suspicion

Originally applying solely to chefs, waiters, dishwashers and the like, New York City (NYC) regulations governing cabaret employees were altered in 1943 to include musicians and entertainers, who until the late 1960’s would be required to hold a NYC Cabaret Employee’s Identification Card. The introduction of these notorious “police cards” occurred roughly contemporaneously to the emergence in after-hours night clubs in Harlem of a new and supposedly “wild”, improvisatory brand of jazz: bebop. This article adds to the many rather practical theories on why these cards were introduced a more abstract discussion coined in terms of the relationship between suspicion and tradition and focusing on differing essences of law and improvisatory jazz. While law breathes tradition and is suspicious of improvisation and unpredictability, the converse is true of jazz. Allusion to tradition in jazz improvisation is often viewed as a betrayal of its creative and spontaneous nature. And yet it is only through its departure from the stable transmission of past meaning that improvisation gains meaning. Law, in contrast, while appearing to be entirely composed of tradition, to transmit some sort of determinate and fixed meaning, is constantly betraying itself. As no two legal actions can be exactly the same, judges must improvise on tradition and past precedent every time they are asked to decide a case. Law can thus neither dispense with nor be completely determined by tradition. The legal decision instead lies on the border between what it “is” and what it otherwise could be and every judicial act is, in some sense, a species of improvisation. This article uses the cabaret cards to explore this uncertain terrain between law and improvisation, between tradition and suspicion.

Biodiversity loss and ecosystem functioning: Distinguishing between number and identity of species

Given currently high rates of extinction, it is critical to be able to predict how ecosystems will respond to loss of species and consequent changes in community structure. Much previous research in this area has been based on terrestrial systems, using synthetically assembled communities. There has beer! much less research on inter-trophic effects in different systems, using in situ removal experiments. Problems with the design of early experiments have made it difficult to determine whether reductions in ecosystem functioning in low diversity treatments were due to the number of species present or merely to the reduced likelihood of including particular (

‘It ain’t easy being green’: Sustainable Development between Environment and Economy in Northern Ireland’

Given the relative lack of research on sustainable development in Northern Ireland, this paper focuses on the tensions between environmental governance and regulation on the one hand, and the ‘post-conflict’ imperative for Northern Ireland to compete and grow as a regional economy without continued British state subvention and subsidisation. The paper outlines how this ‘trade-off’ between ‘environment’ and ‘economy’ is essentially misplaced. It argues that this trade-off can be avoided if there is a shift in focus from an ‘environment versus the economy’ policy position to one in which the ‘triple bottom line’ (social, economic and environmental) of sustainable development becomes the over-arching policy agenda. Sustainable development, unlike either orthodox environmental or economic policy, also connects centrally with the unique ‘post-conflict transformation’ agenda of Northern Ireland. For example, promoting a human rights civic culture, tackling socioeconomic inequality and social exclusion, and building a shared future based on supporting sustainable communities and an innovative model of a ‘green(ing) economy’ goes beyond orthodox economic growth. However, it is clear from the Executive’s Programme for Government, failure to support the creation of an independent Environment Protection Agency, and above all the prioritisation of orthodox economic growth based on foreign direct investment that neither environmental protection nor sustainable development is or will be high on the political or policy agenda in Northern Ireland.

Distance between home and work: A multilevel analysis of individual workers, neighbourhoods, and employment sites in Northern Ireland

Abstract. We explore the distances between home and work for employees at twenty-eight different employment sites across Northern Ireland. Substantively, this is important for better understanding the geography of labour catchments. Methodologically, with data on the distances between place of residence (566 wards) and place of work for some 15 000 workers, and the use of multilevel modelling (MLM), the analysis adds to the evidence derived from other census-based and survey-based studies. Descriptive analysis is supplemented with MLM that simultaneously explores individual, neighbourhood, and site variations in travel-to-work patterns using hierarchical and cross-classified model specifications, including individual and ecological predictor variables (and their cross-level interactions). In doing so we apportion variability to different levels and spatial contexts, and also outline the factors that shape spatial mobility. We find, as expected, that factors such as gender and occupation influence the distance between home and work, and also confirm the importance of neighbourhood characteristics (such as population density observed in ecological analyses at ward level) in shaping individual outcomes, with major differences found between urban and rural locations. Beyond this, the analysis of variability also points to the relative significance of residential location, with less individual variability in travel-to-work distance between workers within wards than within employment sites. We conclude by suggesting that, whilst some general ‘rules’ about the factors that shape labour catchments are possible (eg workers in rural areas and in higher occupations travel further than others), the complex variability between places highlighted by the MLM analysis illustrates the salience of place-specific uniqueness.