Invasiveness of plants is predicted by size and fecundity in the native range

This is the final version of the article. Available from Wiley via the DOI in this record.An important goal for invasive species research is to find key traits of species that predispose them to being invasive outside their native range. Comparative studies have revealed phenotypic and demographic traits that correlate with invasiveness among plants. However, all but a few previous studies have been performed in the invaded range, an approach which potentially conflates predictors of invasiveness with changes that happen during the invasion process itself. Here, we focus on wild plants in their native range to compare life-history traits of species known to be invasive elsewhere, with their exported but noninvasive relatives. Specifically, we test four hypotheses: that invasive plant species (1) are larger; (2) are more fecund; (3) exhibit higher fecundity for a given size; and (4) attempt to make seed more frequently, than their noninvasive relatives in the native range. We control for the effects of environment and phylogeny using sympatric congeneric or confamilial pairs in the native range. We find that invasive species are larger than noninvasive relatives. Greater size yields greater fecundity, but we also find that invasives are more fecund per-unit-size. SYNTHESIS: We provide the first multispecies, taxonomically controlled comparison of size, and fecundity of invasive versus noninvasive plants in their native range. We find that invasive species are bigger, and produce more seeds, even when we account for their differences in size. Our findings demonstrate that invasive plant species are likely to be invasive as a result of both greater size and constitutively higher fecundity. This suggests that size and fecundity, relative to related species, could be used to predict which plants should be quarantined.We thank the National Trust and Cornwall Wildlife Trust for access to field sites, Dr. Colin French for use of the ERICA database, and Luke Davis and Cheryl Mills for assistance during data collection. KJ was supported by the University of Exeter as part of its wildlife research partnership with DEFRA's National Wildlife Management Centre. DH was supported by the Natural Environment Research Council grant reference NE/L007770/1

Modifications to the Aesop's Fable paradigm change New Caledonian crow performances

While humans are able to understand much about causality, it is unclear to what extent non-human animals can do the same. The Aesop's Fable paradigm requires an animal to drop stones into a water-filled tube to bring a floating food reward within reach. Rook, Eurasian jay, and New Caledonian crow performances are similar to those of children under seven years of age when solving this task. However, we know very little about the cognition underpinning these birds' performances. Here, we address several limitations of previous Aesop's Fable studies to gain insight into the causal cognition of New Caledonian crows. Our results provide the first evidence that any non-human animal can solve the U-tube task and can discriminate between water-filled tubes of different volumes. However, our results do not provide support for the hypothesis that these crows can infer the presence of a hidden causal mechanism. They also call into question previous object-discrimination performances. The methodologies outlined here should allow for more powerful comparisons between humans and other animal species and thus help us to determine which aspects of causal cognition are distinct to humans.Publisher PDFPeer reviewe

Transparent and flexible polymerized graphite oxide thin film with frequency-dependent dielectric constant

Here we report on the preparation of transparent and flexible polymerized graphite oxide, which is composed of carbons with sp3-hybridized orbitals and a non-planar ring structure, and which demonstrates dispersion in its dielectric constant at room temperature. This frequency dependence renders the material suitable for creating miniaturized, flexible, and transparent variable capacitors, allowing for smaller and simpler integrated electronic devices. We discuss this polarizability in terms of space charge effects

The Comparative Demography of Invasive Plants

Biodiversity, ecosystems, industry and human health are threatened by invasive plant species. The costs of mitigating damages run into billions of pounds per annum. Fundamental to the control of invasive plant species is an ability to predict which species will become invasive. Yet identification of predictive differences between invasive and non-invasive species has proven difficult to pinpoint. In this thesis I identify several weaknesses within published literature, and using field experiments and meta-analyses we address these to find consistent predictors of invasiveness amongst plants. Specifically, I recognize that predictors of invasiveness can be identified by studying plant species in the native range because species may undergo phenotypic and demographic changes following naturalization (Chapters 2 – 5). I also recognize the importance of comparing globally invasive and non-invasive species, and the importance of accounting for phylogenetic relationships so as not to inflate or conceal differences (Chapters 2 – 4). Finally, I investigate whether particular analyses are more appropriate for investigating life history and demographic differences (Chapter 5). This thesis comprises an introductory chapter (Chapter 1), four data chapters (Chapters 2 - 5) and a general discussion (Chapter 6). Chapters 2 and 3 compare life history traits of plant species known to be invasive elsewhere, with their exported but non-invasive sympatric relatives in the native range. Chapter 4 utilizes Population Projection Matrices held within the COMPADRE Plant Matrix Database, to compare demographic projections of stable and transient dynamics of invasive and non-invasive plants; and Chapter 5 compares ten metrics, derived from Population Projection Matrices, of seven invasive species between the native and invaded range to determine if there are demographic or life history differences that facilitate invasion, and to identify those analyses that are most likely to reveal such differences. I find reproductive capacity to be a predictor of invasiveness, and that analyses of transient dynamics are more likely than analyses of projected stable dynamics to reveal demographic or life history differences between invasive and non-invasive species or populations of plants. I discuss these findings in the context of invasive risk assessment protocols and highlight future research opportunities

History dependent magnetoresistance in lightly doped La_{2-x}Sr_{x}CuO_{4} thin films

The in-plane magnetoresistance (MR) in atomically smooth La_{2-x}Sr_{x}CuO_{4} thin films grown by molecular-beam-epitaxy was measured in magnetic fields B up to 9 T over a wide range of temperatures T. The films, with x=0.03 and x=0.05, are insulating, and the positive MR emerges at T<4 K. The positive MR exhibits glassy features, including history dependence and memory, for all orientations of B. The results show that this behavior, which reflects the onset of glassiness in the dynamics of doped holes, is a robust feature of the insulating state.Comment: 4 pages, 4 figures, International School and Workshop on Electronic Crystals (ECRYS-2011); to appear in Physica

Sex Trafficking and State Intervention: Conflicts and Contradictions during the 2012 London Olympics

This thesis focuses on the British human trafficking prevention policies adopted for the 2012 London Olympics using mixed methods including participation-observation, qualitative interviews, theoretical analysis and policy evaluation. I was invited to observe the Human Trafficking Network and London 2012, the Mayor of London’s official response to the claim that human trafficking would increase at the London Olympics. My presence enabled me to witness first-hand the key policy debates surrounding human trafficking intervention and to conduct a series of in-depth interviews with members of the Human Trafficking Network as well as associated professionals such as the United Kingdom Human Trafficking Centre, MPs, governmental and non-governmental agencies, law enforcement officials, anti-trafficking groups, sex workers, sex workers outreach services and academics. In addition to collecting rich empirical data, I contexualise these policy debates within two relevant theoretical frameworks. First, I draw upon the work of Weitzer (2007) to examine the construction of the four underlying claims that human trafficking increases before and during large sporting events. Significantly, this perspective is built upon an anti-prostitution agenda of the partial criminalisation proponents, which collapses all migration for prostitution together with human trafficking (Weitzer 2005, Kempadoo 2005, Milivojevic and Pickering 2008, Kinnell 2009, Mai 2009, Mai 2012, Weitzer 2014). This same conceptualisation of human trafficking as the nexus of prostitution, migration and crime is replicated within the global anti-trafficking framework (Milivojevic and Pickering 2013), resulting in two approaches to human trafficking prevention policies — Security Governance and Human Rights — which together resulted in preventions measures that target prostitution and control migration. Finally, I draw upon my empirical evidence to critically examine the effects of the claim that human trafficking increases over the Olympics and, moreover, situate the response by the Mayor of London within the global anti-trafficking framework. This framework highlights the contradictions and, in some instances, failures between the approaches to human trafficking and the stated purpose of the Human Trafficking Network. The thesis concludes with two innovative policy recommendations for human trafficking prevention programmes.Dr Mike and Mrs Patricia Jelbert, Cambridge Political Economy Society Trust, The Sir Richard Stapley Educational Trust, Al Charitable Trust, Philip Lake Fund, University of Cambridge and Funds for Women Graduates

Modifications to the Aesop's fable paradigm change New Caledonian crow performances

While humans are able to understand much about causality, it is unclear to what extent non-human animals can do the same. The Aesop's Fable paradigm requires an animal to drop stones into a water-filled tube to bring a floating food reward within reach. Rook, Eurasian jay, and New Caledonian crow performances are similar to those of children under seven years of age when solving this task. However, we know very little about the cognition underpinning these birds' performances. Here, we address several limitations of previous Aesop's Fable studies to gain insight into the causal cognition of New Caledonian crows. Our results provide the first evidence that any non-human animal can solve the U-tube task and can discriminate between water-filled tubes of different volumes. However, our results do not provide support for the hypothesis that these crows can infer the presence of a hidden causal mechanism. They also call into question previous object-discrimination performances. The methodologies outlined here should allow for more powerful comparisons between humans and other animal species and thus help us to determine which aspects of causal cognition are distinct to humans

The Book of Chronicles and Colophonic Chronography

This thesis examines the repeating citation formulae in the biblical book of Chronicles to discover their nature, purpose and function. The principle focus of this study will be on the repeating formulae, especially the citation references: “And the rest of the acts of King X, first and last, are found in the book of the Kings of Judah and Israel,” or other such references. These usually appear at the end of each king’s reign. In addition, the ending of Chronicles which is repeated at the start of Ezra will be reviewed. Variously designated by different scholars as “titles,” “conclusion formulae” and even “Stichzeile” (catchlines), there is no scholarly consensus about these formulaic citations or their role within Chronicles. An overview of the history of scholarly views on authorship, dating and genre in the book of Chronicles is conducted here, where it may be seen that today there is no settled view on these isagogic elements, which would seem to justify not assuming the isagogic elements a priori. From this starting point the Chronicles’ citation formulae are compared and contrasted with those in the ancient Near Eastern epigraphic materials, especially those of Babylon and Assyria, where colophons are a feature of chronographic literature. A brief look at Egyptian epigraphy is included too. Overall, the thesis finds that these share similar features with those in biblical Chronicles, but also significant differences, depending on the period being examined. The next step is to make an inner biblical comparison of Chronicles’ citations with those found in Kings. Samuel is also examined, and parts of Isaiah and Jeremiah, where relevant. The findings of the ancient Near Eastern comparison of the citation formulae, and the internal biblical comparison with Kings’ source citations, lead to a proposal that points to a genre classification of “Chronicles” with all that this implies about a running account and a pre-exilic commencement date in the time of the first temple of Solomon

How flexible is tool use in Eurasian jays (Garrulus glandarius)?

Eurasian jays (Garrulus glandarius) do not habitually use tools, yet they can be trained to solve object-dropping tasks, i.e., to insert a tool into an apparatus to release a food reward. Previous research suggests that these jays can learn a preference toward functional tools – objects allowing them to obtain a food reward placed inside an apparatus – according to their density (Cheke et al., 2011). However, it is not yet known whether they can also select functional tools (tool selectivity) according to other physical properties such as size and shape and use different kinds of tools to solve a similar task. Here we conducted three object-dropping experiments aimed at exploring these abilities in Eurasian jays. In Experiment 1, jays tended to select large stones as tools irrespective of the diameter of the apparatus. However, jays progressively developed a preference for the small tool, which was functional with both the wide and the narrow apparatuses. In Experiment 2, only vertically oriented long stones could fit into the narrow apparatus, whereas both long and round stones were functional with the wide apparatus. Jays showed a preference for the long stone and, with the narrow apparatus, tended to achieve the correct manipulation after one or more unsuccessful attempts. In Experiment 3, jays were able to use sticks and adopt a novel technique on the same object-dropping apparatus, thus providing the first evidence that Eurasian jays can use sticks as tools. Taken together, these results do not support the notion that tool selectivity abilities can be found in Eurasian jays but nonetheless show that these corvids can use different kinds of tools to solve similar tasks