bluuebunny/crossref_metadata_2025_split huggingface dataset:
The evolution of facilitation and mutualism
Authors: Bronstein Judith L. 
Published: October 2009

Summary1.While the relationship between facilitation and competition has been explored extensively in recent years, there is also a natural link between facilitation and mutualism, as both are interspecific interactions that confer benefits. Yet, the relationship between these two interactions has been minimally explored.2.Here, I explore parallels and differences between mutualism and facilitation. Five focal areas organize current research on mutualism evolution: trait evolution; the continuum from specialization to generalization; the evolutionary origins and maintenance of the interaction; co‐evolution of partners; and the prevalence and implications of cheating. These foci are also helpful for investigating how facilitation evolves, a much less explored issue.3.Testable hypotheses regarding the evolution of facilitation include the following: selection should be stronger on traits of facilitated species than on traits of facilitators; facilitative interactions with mutualistic (++) and commensal (+0) outcomes should exhibit greater evolutionary stability than those with antagonistic (+−) outcomes; co‐evolution should be possible in mutualistic and antagonistic facilitation only; when co‐evolution occurs, it should produce a geographic mosaic of interaction outcomes; and antagonistic facilitation could lead to selection on facilitators to either escape or to tolerate the neighbours that benefit from them.4.Synthesis. Three gaps in our knowledge currently impede progress on evolutionary questions surrounding facilitation. First, reciprocal effects are rarely investigated; facilitation might evolve like mutualism, commensalism or antagonism, depending on effects on the facilitator species. Secondly, the genetics of relevant traits are not yet well explored; the traits themselves are better known for facilitator species than for the facilitated, which are more likely to evolve in the context of the interaction. Finally, the fitness costs and benefits associated with facilitation have rarely been measured. Filling these gaps should permit rapid progress in understanding how facilitation arises, persists and evolves.
Facilitation research in marine systems: state of the art, emerging patterns and insights for future developments
Authors: Bulleri Fabio 
Published: October 2009

Summary 1. Positive species interactions are increasingly recognized as important drivers of community structure and ecosystem functioning. Although the literature on facilitative interactions in terrestrial environments has been reviewed and emerging patterns have been synthesized, comparable attempts are lacking for the marine realm. 2. By means of a quantitative survey of the literature, I provide a critical summary of current knowledge on positive species interactions in marine environments. In particular, I (i) assess how marine facilitation research compares to that carried out in terrestrial environments in terms of focus and philosophical approach; (ii) illustrate the mechanisms by which facilitation takes place in different habitats; (iii) assess whether benefactor and beneficiary species are more likely to belong to the same or to a different trophic level; and (iv) provide examples of how including facilitation into ecological theory might advance our understanding of the mechanisms that regulate ecosystem functioning. 3. Except for some studies in intertidal habitats, few studies in marine environments have been framed within mainstream facilitation theory (e.g. the Stress Gradient Hypothesis) and research does not seem to be organized in a self‐contained theme. Amelioration of physical conditions appears to be the most common mechanism of facilitation in intertidal habitats, whilst associational defence predominates in the subtidal. 4. In contrast to the terrestrial literature, dominated by plant–plant interactions, marine benefactors and beneficiary species often belong to different trophic levels. This might imply little overlapping of resource niches or a differential response to environmental conditions or consumer pressure, with implications for the persistence of facilitative effects at the extreme ends of stress gradients. 5. Recent research shows that facilitation can enhance temporal variability and invasibility of marine communities and emphasizes the central role of positive species interactions in regulating the functioning of natural ecosystems. 6.
Synthesis. Studies encompassing a wide variety of life histories and environmental conditions are central to achieving a unified facilitation theory. Research in marine environments can provide new insights into the mechanisms underlying variations in the strength and direction of species interactions, but this will require greater awareness and consideration of facilitation.
The role of plant interactions in the restoration of degraded ecosystems: a meta‐analysis across life‐forms and ecosystems
Authors: Gómez‐Aparicio Lorena 
Published: October 2009

Summary1. Traditionally, techniques of plant manipulation during restoration have focused on the reduction of competition by ‘problematic’ existing vegetation. However, the increasing recognition of facilitation as a main process regulating the composition of communities has brought a change in the practice of restoration towards a better awareness of the benefits inherent to conserving neighbouring vegetation.2. Here, I provide the results of a meta‐analysis of published studies that have manipulated interactions among plants with the objective of restoring degraded terrestrial systems. I created four different data sets corresponding to the variables most commonly used to measure plant performance (i.e. emergence, survival, growth and density), and asked whether the benefits of facilitation as a restoration tool vary depending on the study duration, the life‐form of the neighbour and target species, and the ecosystem type.3. Neighbour effects varied strongly among performance estimators. Positive effects were frequently found for emergence and survival, whereas neutral or negative interactions predominated for growth and density.4. No clear support existed for a relationship between study duration and neighbour effect.5. The life‐form of the interacting species, particularly of neighbours, largely influenced the interaction outcome. Herbs had strong negative effects, especially on other herb species, whereas shrubs had large facilitative effects, especially on trees.6. Semiarid and tropical systems showed in general more positive neighbour effects than wetlands and particularly mesic temperate systems, where negative interactions predominated. However, these results were largely influenced by the over‐representation of herb species in wetlands and temperate habitats, survival facilitation being found in all systems when only woody species were considered.7. Synthesis.Pre‐existing vegetation can have large impacts on species establishment in degraded habitats. Inhibition predominates in herbaceous communities typical of early‐successional stages, whereas facilitation prevailes in communities dominated by shrubs and trees. Even productive systems (e.g. mesic temperate habitats) appear suitable for the application of facilitation as a restoration tool of woody communities. Whereas restoring herbaceous communities seems largely reliable on removal techniques, augmenting populations of nurse shrubs and trees should be considered a promising strategy for restoring woody late‐successional communities.
Facilitation in the conceptual melting pot
Authors: Brooker Rob W. , Callaway Ragan M. 
Published: October 2009

Summary 1. Here we present an introduction to this issue’s Special Feature arising from the British Ecological Society Symposium: Facilitation in Plant Communities (20–22 April 2009). 2. Papers in the Special Feature demonstrate the benefits that arise from cross‐system application of general concepts, for example, the well‐known stress gradient hypothesis. Such comparisons challenge our definition of facilitation, as well as our pre‐conceptions on the nature of intermediary organisms. 3. We suggest that under some circumstances a clear definition of the two‐way nature of interactions is essential, e.g. when considering the evolutionary implications of facilitation. In other cases, however, we can perhaps be more relaxed, e.g. when facilitation is a component of conservation ecology. 4.
Synthesis. Overall we believe that establishing facilitation as an independent concept has driven substantial progress towards a clearer understanding of how ecological systems work. Through the links established by work such as that presented in this Special Feature, we believe this field will continue to make rapid progress and aid ecological understanding in general.
Cardiovascular outcomes and their relationships to lipoprotein components in patients with and without chronic kidney disease: results from the IDEAL trial
Authors: Holme I. , Fayyad R. , Faergeman O. , Kastelein J. J. P. , Olsson A. G. , Tikkanen M. J. , Larsen M. L. , Lindahl C. , Holdaas H. , Pedersen T. R. ,   On behalf of the Incremental Decrease in End Points Through Aggressive Lipid Lowering Study Group
Published: October 2009

Abstract.  Holme I, Fayyad R, Faergeman O, Kastelein JJP, Olsson AG, Tikkanen MJ, Larsen ML, Lindahl C, Holdaas H, Pedersen TR, On behalf of the Incremental Decrease in End Points Through Aggressive Lipid Lowering Study Group (Centre of Preventive Medicine, Oslo, Norway; Århus University Hospital, Århus, Denmark; Academic Hospital Amsterdam, Amsterdam, The Netherlands; University Hospital, Linköping, Sweden; Helsinki University Central Hospital, Helsinki, Finland; Oslo University Hospital, Rikshospitalet, Oslo, Norway; Pfizer Sweden, Sollentuna, Sweden; and Pfizer Inc., New York, NY, USA). Cardiovascular outcomes and their relationships to lipoprotein components in patients with and without chronic kidney disease: Results from the IDEAL trial. J Intern Med 2010; 267:567–575.Objectives.  In Incremental Decrease in Endpoints through Aggressive Lipid‐lowering (IDEAL), we compared cardiovascular outcomes in patients with and without chronic kidney disease (CKD) (estimated glomerular filtration rate <60 mL min−1 1.73 m−2) and analysed relationships between lipoprotein components (LC) and major coronary events (MCE) and other cardiovascular (CV) events.Design.  Exploratory analysis of CV endpoints in a randomized trial comparing high dose of atorvastatin to usual dose of simvastatin on MCE.Settings.  Patients with CKD were compared with the non‐CKD patients. Cox regression models were used to study the relationships between on‐treatment levels of LC and incident MCE.Findings.  Chronic kidney disease was strongly associated with cardiovascular end‐points including total mortality. In patients with CKD, a significant benefit of high dose atorvastatin treatment was found for any CV events, stroke and peripheral artery disease, but not for MCE. However, all cardiovascular end‐points except stroke and CV mortality were reduced in the non‐CKD group. Differential changes in LC or relationships to LC could not explain the different treatment outcomes in MCE in the two groups.Interpretation.  Chronic kidney disease was a powerful risk factor for all cardiovascular end‐points. The reason why the significant reductions achieved by high‐dose statin treatment in most CV end‐points in the non‐CKD group were only in part matched by similar reductions in the CKD patients is not apparent. This difference did not result from differential changes in or relations to LC, but limited power may have increased the possibility of chance findings.
Identifying glacial refugia in a geographic parthenogen using palaeoclimate modelling and phylogeography: the New Zealand stick insect Argosarchus horridus (White)
Authors: BUCKLEY THOMAS R. , MARSKE KATHARINE A. , ATTANAYAKE DILINI 
Published: October 2009

AbstractWe have used phylogeographic analysis of mitochondrial DNA (COI and COII genes) and ecological niche modelling (ENM) to reconstruct the population history of Argosarchus horridus (White), a widespread species of New Zealand stick insect. These data were used to address outstanding questions on the role of glacial refugia in determining the distribution and genetic structure of New Zealand species. Phylogeographic analysis shows a general pattern of high diversity in upper North Island and reduced diversity in lower North Island and South Island. The ENM indicates that during the last glacial maximum, A. horridus was largely restricted to refugia around coastal areas of North Island. The ENM also suggests refugia on the northeast coast of South Island and southeast coast of North Island and this prediction is verified by phylogeographic analysis, which shows a clade restricted to this region. Argosarchus horridus is also most likely a geographic parthenogen where males are much rarer at higher latitudes. The higher levels of genetic variation in northern, bisexual populations suggest southern and largely unisexual populations originated from southwardly expanding parthenogenetic lineages. Bayesian skyline analysis also provides support for a recent population size increase consistent with a large increase in geographic distribution in the late Pleistocene. These results exemplify the utility of integrating ENM and phylogeographic analysis in testing hypotheses on the origin of geographic parthenogenesis and effects of Pleistocene environmental change on biodiversity.
Breast feeding very‐low‐birthweight infants at discharge: a multicentre study using WHO definitions
Authors: Davanzo Riccardo , Ronfani Luca , Brovedani Pierpaolo , Demarini Sergio 
Published: October 2009

SummaryHuman milk has several advantages in the nutrition of very‐low‐birthweight (VLBW) infants. However, there are limited data on breast feeding (BF) in neonatal intensive care units (NICU). The aim of this study was to identify a practical definition of BF rate in VLBW infants and to test its applicability and reproducibility in Italian NICUs. The study population included all VLBW infants discharged from 12 level 3 NICUs, over a 12‐month period. Type of feeding was recorded according to the World Health Organisation (WHO) definition, with a 72‐h recall period.We enrolled 594 VLBW infants. Mean birthweight was 1105 g (SD: 267), mean gestational age was 29.2 weeks (SD: 2.7) and mean length of stay in NICUs was 62.5 days (SD: 56.5). At discharge, 30.5% of VLBW infants were exclusively breast fed, 0.2% were predominantly breast fed, 23.8% were on complementary feeding and 45.5% were exclusively formula fed. A wide variability in BF rates was seen between centres. Among exclusively breast‐fed VLBW infants, only 10% sucked directly and exclusively at the breast. WHO definitions can be used to assess type of feeding at discharge from NICUs. We speculate that common feeding definitions may allow both comparisons among different NICUs and ratings of quality improvement programmes.
Relationships between birthweight and biomarkers of chronic disease in childhood: Aboriginal Birth Cohort Study 1987–2001
Authors: Sayers Susan , Singh Gurmeet , Mott Susan , McDonnell Joseph , Hoy Wendy 
Published: October 2009

SummaryReports of relationships between lower birthweight and later chronic diseases are mainly from populations with low rates of low birthweight (LBW) and growth‐restricted births. A prospective study of an Australian Aboriginal birth cohort with a mean birthweight of 3050 g (SD 630), 16% LBW and 28% fetal growth restriction was used to examine the relationships between birthweight and selected biomarkers of chronic adult disease.At a mean age of 11.4 years (range 8.9–14), the mean weight was 35.7 kg (SD 11.8) and the mean height was 143.8 cm (SD 10.6). Using the Centers for Disease Control and Prevention (CDC) 2000 growth references, weight and height‐for‐age z‐scores were −0.8 (SD 1.4) and −0.5 (SD 1.07) respectively and using World Health Organisation criteria, 19% of children were classified as underweight (weight for age Z‐score <2.0). The relationships between birthweight and blood pressure (n = 475), total cholesterol (n = 461), Apolipoprotein A‐1 (n = 343), Apolipoprotein B (n = 390), respiratory function tests (n = 427), kidney size determined by ultrasound (n = 446), urinary albumin/creatinine ratio (n = 420) and fasting triglycerides (n = 281), insulin (n = 272) and glucose (n = 279) were examined using regression models adjusted for sex, gestational age, current age and puberty status. In this population with high rates of fetal growth restriction at birth and an excess of under‐nutrition at age 11 years we found that birthweight had a negative relationship with child blood pressure only, while current child weight was positively related to blood pressure, total cholesterol, Apolipoprotein B, respiratory function tests, kidney size, and fasting triglycerides, insulin and glucose.
Understanding the factors associated with differences in caesarean section rates at hospital level: the case of Latin America
Authors: Taljaard Monica , Donner Allan , Villar José , Wojdyla Daniel , Faundes Anibal , Zavaleta Nelly , Acosta Arnaldo 
Published: October 2009

SummaryAs in many other regions of the world, caesarean section (CS) rates in Latin America are increasing. Studies elsewhere have shown that providing feedback to caregivers regarding their own performance relative to their peers can significantly reduce the rates. Our objectives are to calculate risk‐adjusted CS rates for hospitals in Latin America and to identify factors associated with differences among risk‐adjusted rates. We included 120 randomly selected institutions in eight countries of Latin America, representing 97 095 pregnancies. We used random‐effects models to calculate a risk‐adjusted rate for each hospital and to identify hospitals significantly higher or lower than a benchmark rate. We conducted a regression analysis to identify characteristics of hospitals associated with differences among risk‐adjusted rates.The overall CS rate was 35%, ranging from 0% to 85%. Risk‐adjusted CS rates ranged from 11% to 78%. Three‐quarters of hospitals had risk‐adjusted rates significantly above the previously identified benchmark of 20%. Characteristics of institutions explained 48% of the variability among risk‐adjusted rates, including being a private as opposed to a public institution, having some economic incentive for CS as opposed to no incentive, and having ≥50 maternity beds.Strategies to halt further increases in CS rates and reduce rates to levels that reflect the best quality of care, are urgently needed worldwide. The involvement of local quality control departments is an essential component in achieving success. Our results can be used to identify institutions that can be targets for further interventions to reduce CS rates.
Basal metabolic rate and risk‐taking behaviour in birds
Authors: MØLLER A. P. 
Published: October 2009

AbstractBasal metabolic rate (BMR) constitutes the minimal metabolic rate in the zone of thermo‐neutrality, where heat production is not elevated for temperature regulation. BMR thus constitutes the minimum metabolic rate that is required for maintenance. Interspecific variation in BMR in birds is correlated with food habits, climate, habitat, flight activity, torpor, altitude, and migration, although the selective forces involved in the evolution of these presumed adaptations are not always obvious. I suggest that BMR constitutes the minimum level required for maintenance, and that variation in this minimum level reflects the fitness costs and benefits in terms of ability to respond to selective agents like predators, implying that an elevated level of BMR is a cost of wariness towards predators. This hypothesis predicts a positive relationship between BMR and measures of risk taking such as flight initiation distance (FID) of individuals approached by a potential predator. Consistent with this suggestion, I show in a comparative analysis of 76 bird species that species with higher BMR for their body mass have longer FID when approached by a potential predator. This effect was independent of potentially confounding variables and similarity among species due to common phylogenetic descent. These results imply that BMR is positively related to risk‐taking behaviour, and that predation constitutes a neglected factor in the evolution of BMR.
Clinal variation in post‐winter male fertility retention; an adaptive overwintering strategy in Drosophila melanogaster
Authors: RAKO L. , POULSEN N. A. , SHIRRIFFS J. , HOFFMANN A. A. 
Published: October 2009

AbstractIn insects including Drosophila melanogaster, females can overwinter at the adult stage by adopting a shallow reproductive diapause, but almost nothing is known about male reproductive diapause. In this study, we test for the maintenance of fertility in overwintering males from the eastern Australian D. melanogaster cline. Males from southern temperate populations maintained in field cages in temperate Melbourne had a higher fertility in spring compared with males from tropical locations. Temperate males successfully inseminated more females, and there were also more offspring produced per inseminated female. The resulting linear post‐winter fertility clines were unrelated to male body size. In contrast, there was no clinal variation for fertility in nonoverwintering males held in the laboratory. The cline in overwintering male fertility is likely to have evolved as an adaptive response to latitudinal climatic variation over the last 100 years.
Refined mapping of quantitative trait loci for somatic cell score on BTA02 in the German Holstein
Authors: Baes C. , Goertz I. , Mayer M. , Weimann C. , Liu Z. , Reinhardt F. , Erhardt G. , Reinsch N. 
Published: October 2009

SummaryThe aim of this study was to more precisely map a previously reported quantitative trait locus (QTL) affecting somatic cell score on Bos taurus autosome 2 by increasing the number of markers fourfold, analysing more families and exploiting within‐population linkage disequilibrium (LD). A granddaughter design of 10 German Holstein grandsire families with 1121 progeny tested sons was used. Twenty‐six markers with an average marker spacing of 3.14 cM were genotyped along 81.6 cM. Linkage analysis (LA) was performed using variance‐component methodology. The incorporation of LD was first done using variance‐component methods followed by regression on marker alleles. LA revealed genome‐wide significance (LOD > 3) at 15 contiguous marker‐intervals, with the maximum test‐statistic between DIK2862 and BMS778 and a 1‐lod drop‐off interval of 38 cM. While the variance‐component methods could not detect any LD, two individual markers with a significant effect (ILSTS098, p < 0.05; BMS778, p < 0.01) were found by regression analysis. Compared with previous results QTL‐localisation was substantially narrowed; further fine‐mapping should focus on the close vicinity of BMS778.