Simplification of structured population dynamics in complex ecological communities

Goldstone's idea of slow dynamics resulting from spontaneously broken symmetries is applied to Hubbell's neutral hypothesis of community dynamics, to efficiently simplify stage-structured multi-species models-introducing the quasi-neutral approximation (QNA). Rather than assuming population-dynamical neutrality in the QNA, deviations from ideal neutrality, thought to be small, drive dynamics. The QNA is systematically derived to first and second order in a two-scale singular perturbation expansion. The total reproductive value of species, as computed from the effective life-history parameters resulting from the non-linear interactions with the surrounding community, emerges as the new dynamic variables in this aggregated description. Using a simple stage-structured community-assembly model, the QNA is demonstrated to accurately reproduce population dynamics in large, complex communities. Further, the utility of the QNA in building intuition for management problems is illustrated by estimating the responses of a fish stock to harvesting and variations in fecundity.

Habitat simplification increases the impact of a freshwater invasive fish

Biodiversity continues to decline at a range of spatial scales and there is an urgent requirement to understand how multiple drivers interact in causing such declines. Further, we require methodologies that can facilitate predictions of the effects of such drivers in the future. Habitat degradation and biological invasions are two of the most important threats to biodiversity and here we investigate their combined effects, both in terms of understanding and predicting impacts on native species. The predatory largemouth bass Micropterus salmoides is one of the World’s Worst Invaders, causing declines in native prey species, and its introduction often coincides with habitat simplification. We investigated the predatory functional response, as a measure of ecological impact, of juvenile largemouth bass in artificial vegetation over a range of habitat complexities (high, intermediate, low and zero). Prey, the female guppy Poecilia reticulata, were representative of native fish. As habitats became less complex, significantly more prey were consumed, since, even although attack rates declined, reduced handling times resulted in higher maximum feeding rates by bass. At all levels of habitat complexity, bass exhibited potentially population destabilising Type II functional responses, with no emergence of more stabilising Type III functional responses as often occurs in predator-prey relationships in complex habitats. Thus, habitat degradation and simplification potentially exacerbate the impact of this invasive species, but even highly complex habitats may ultimately not protect native species. The utilisation of functional responses under varying environmental contexts provides a method for the understanding and prediction of invasive species impacts.

England, Neo-Latin, and the Continental Journey: Linguistic and Textual Itineraries

This chapter examines the ramifications of continental travel and associated epistolary communication for English poets of the period. It argues that recourse to neo-Latin, the universal language of diplomacy, served not only to establish a sense of shared space—linguistic, cultural, generic—between England and the continent, but also to signal self-conscious differences (climatic, geographical, historical, political) between England and her continental peers. Through an investigation of a range of ‘performances’ on stages that were ‘academic’, poetic, autobiographical, and epistolographic, it assesses the central role of neo-Latin as a language that underwent a series of textual itineraries. These ‘itineraries’ manifest themselves in a number of ways. Neo-Latin as a shared linguistic medium can facilitate, and quite uniquely so, intertextual engagement with the classics, but now ancient Rome, its language, its mythology, its hierarchy of genres, are viewed through a seventeenth-century lens and appropriated by poets in both England and Italy to describe contemporary events, whether personal, or political. Close examination of the neo-Latin poetry of Milton and Marvell reveals, it is argued, a self-fashioning coloured by such textual itineraries and interchanges. The absorption and replication of continental literary and linguistic methodologies (the academic debate; the etymological play of Marinism; the hybridity of neo-Latin and Italian voices) reveal in short a linguistic and textual reciprocity that gave birth to something very new.