Matrix projection models occupy a central role in population and conservation biology. Matrix models divide a population into discrete classes, even if the structuring trait exhibits continuous variation (e.g., body size). The integral projection model (IPM) avoids discrete classes and potential artifacts from arbitrary class divisions, facilitates parsimonious modeling based on smooth relationships between individual state and demographic performance, and can be implemented with standard matrix software. Here, we extend the IPM to species with complex demographic attributes, including dormant and active life stages, cross-classification by several attributes (e.g., size, age, and condition), and changes between discrete and continuous structure over the life cycle. We present a general model encompassing these cases, numerical methods, and theoretical results, including stable population growth and sensitivity/ elasticity analysis for density-independent models, local stability analysis in density-dependent models, and optimal/evolutionarily stable strategy life-history analysis. Our presentation centers on an IPM for the thistle Onopordum illyricum based on a 6-year field study. Flowering and death probabilities are size and age dependent, and individuals also vary in a latent attribute affecting survival, but a predictively accurate IPM is completely parameterized by fitting a few regression equations. The online edition of the American Naturalist includes a zip archive of R scripts illustrating our suggested methods.

Article: Levine, J.M. and Rees, M. (2002) Coexistence and relative abundance in annual plant assemblages: The roles of competition and colonization. American Naturalist, 160 (4). pp. [452][453][454][455][456][457][458][459][460][461][462][463][464][465][466][467] eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. abstract: Although an interspecific trade-off between competitive and colonizing ability can permit multispecies coexistence, whether this mechanism controls the structure of natural systems remains unresolved. We used models to evaluate the hypothesized importance of this trade-off for explaining coexistence and relative abundance patterns in annual plant assemblages. In a nonspatial model, empirically derived competition-colonization trade-offs related to seed mass were insufficient to generate coexistence. This was unchanged by spatial structure or interspecific variation in the fraction of seeds dispersing globally. These results differ from those of the more generalized competition-colonization models because the latter assume completely asymmetric competition, an assumption that appears unrealistic considering existing data for annual systems. When, for heuristic purposes, completely asymmetric competition was incorporated into our models, unlimited coexistence was possible. However, in the resulting abundance patterns, the best competitors/poorest colonizers were the most abundant, the opposite of that observed in natural systems. By contrast, these natural patterns were produced by competition-colonization models where environmental heterogeneity permitted species coexistence. Thus, despite the failure of the simple competition-colonization trade-off to explain coexistence in annual plant systems, this trade-off may be essential to explaining relative abundance patterns when other processes permit coexistence.

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Traditional conservation biology regards environmental fluctuations as detrimental to persistence, reducing long-term average growth rates and increasing the probability of extinction. By contrast, coexistence models from community ecology suggest that for species with dormancy, environmental fluctuations may be essential for persistence in competitive communities. We used models based on California grasslands to examine the influence of interannual fluctuations in the environment on the persistence of rare forbs competing with exotic grasses. Despite grasses and forbs independently possessing high fecundity in the same types of years, interspecific differences in germination biology and dormancy caused the rare forb to benefit from variation in the environment. Owing to the buildup of grass competitors, consecutive favorable years proved highly detrimental to forb persistence. Consequently, negative temporal autocorrelation, a low probability of a favorable year, and high variation in year quality all benefited the forb. In addition, the litter produced by grasses in a previously favorable year benefited forb persistence by inhibiting its germination into highly competitive grass environments. We conclude that contrary to conventional predictions of conservation and population biology, yearly fluctuations in climate may be essential for the persistence of rare species in invaded habitats.

Background: Surgical mortality data are collected routinely in high-income countries, yet virtually no low-or middle-income countries have outcome surveillance in place. The aim was prospectively to collect worldwide mortality data following emergency abdominal surgery, comparing findings across countries with a low, middle or high Human Development Index (HDI).Methods: This was a prospective, multicentre, cohort study. Self-selected hospitals performing emergency surgery submitted prespecified data for consecutive patients from at least one 2-week interval during July to December 2014. Postoperative mortality was analysed by hierarchical multivariable logistic regression.

The development of a method to facilitate clinical negotiation with diabetic patients is described. The principles of the method incorporate patient centredness, an assessment of readiness to change and some elements of motivational interviewing. A simple low cost technology is part of the innovative method. Details of the method and its application are published before the results of a randomized controlled trial to ensure that the techniques are in the public domain before the outcome of the trial is known.

Since the early twenty- first century, a craze for “original ecology folksongs” has overtaken China. Performed by village- born singers in local dialect and obviously traditional style, these songs and the related discourse stress ties to place, cultural authenticity, and the interrelationship of physical environment with human culture. Their aesthetic stands in stark contrast to the twentieth- century preference for European- inspired modernization and standardization of Chinese traditional music. Reflecting widespread Chinese angst over rapid culture loss and major environmental degradation, this song phenomenon and the discussion it provokes resonate productively with Western scholarship in musical sustainability, intangible cultural heritage protection, and ecomusicology.

Dysfunction of the Wilms' Tumour gene (WTl), a transcription factor critical for normal development and function of the urogenital tract, can result in bothtumorigenesis and urogenital abnormalities. The association of WT1 gene mutations with most cases of Denys-Drash syndrome is well described. More recently WT1 mutations have also been described In a related condition, Frasier syndrome. We report a case where genetic analysis showed a WT1 mutation typically associated with Frasier syndrome: a 1228 + 5 guanine to adenine substitution at the 3' alternative splice donor site in intron 9. The case provides a focus for the discussion of recent evidence that Denys Drash and Frasier syndrome form two ends of a spectrum of disorders. In addition, it illustrates the increasing significance of genetic investigation within clinical practice for diagnostic, prognostic and therapeutic purposes and the importance of karyotype analysis in phenotypically normal girls with renal disease.The WTI gene was isolated from chromosome 1 lp13 as a result of a positional cloning effort aimed at identifying the gene for Wilms' tumour (Call et al., 1990;Gessler et al., 1990). Although WT1 does have tumour suppressor qualities, subsequent analysis has demonstrated mutations in only 10-15% of