bluuebunny/crossref_metadata_2025_split huggingface dataset:
Survival of Svalbard pink‐footed geeseAnser brachyrhynchusin relation to winter climate, density and land‐use
Authors: KÉRY MARC , MADSEN JESPER , LEBRETON JEAN‐DOMINIQUE 
Published: August 2006

SummaryGlobal change may strongly affect population dynamics, but mechanisms remain elusive. Several Arctic goose species have increased considerably during the last decades. Climate, and land‐use changes outside the breeding area have been invoked as causes but have not been tested. We analysed the relationships between conditions on wintering and migration staging areas, and survival in Svalbard pink‐footed geeseAnser brachyrhynchus. Using mark–recapture data from 14 winters (1989–2002) we estimated survival rates and tested for time trends, and effects of climate, goose density and land‐use.Resighting rates differed for males and females, were higher for birds recorded during the previous winter and changed smoothly over time. Survival rates did not differ between sexes, varied over time with a nonsignificant negative trend, and were higher for the first interval after marking (0·88–0·97) than afterwards (0·74–0·93). Average survival estimates were 0·967 (SE 0·026) for the first and 0·861 (SE 0·023) for all later survival intervals.We combined 16 winter and spring climate covariates into two principal components axes. F1 was related to warm/wet winters and an early spring on the Norwegian staging areas and F2 to dry/cold winters. We expected that F1 would be positively related to survival and F2 negatively. F1 explained 23% of survival variation (F1,10 = 3·24; one‐sidedP = 0·051) when alone in a model and 28% (F1,9 = 4·50; one‐sidedP = 0·031) in a model that assumed a trend for survival. In contrast, neither F2 nor density, land‐use, or scaring practices on important Norwegian spring staging areas had discernible effects on survival.Climate change may thus affect goose population dynamics, with warmer winters and earlier springs enhancing survival and fecundity. A possible mechanism is increased food availability on Danish wintering and Norwegian staging areas. As geese are among the main herbivores in Arctic ecosystems, climate change, by increasing goose populations, may have important indirect effects on Arctic vegetation. Our study also highlights the importance of events outside the breeding area for the population dynamics of migrant species.
Assessing grassland restoration success: relative roles of seed additions and native ungulate activities
Authors: MARTIN LEANNE M. , WILSEY BRIAN J. 
Published: August 2006

Summary

Grassland restorations often lack rare forb and grass species that are found in intact grasslands. The possible reasons for low diversity include seed limitation, microsite limitation and a combination of both. Native ungulates may create microsites for seedling establishment in tallgrass prairie restorations by grazing dominant species or through trampling activities, but this has never been tested in developing prairies.
We experimentally tested for seed and microsite limitation in the largest tallgrass prairie restoration in the USA by adding rare forb and grass seeds in two trials inside and outside native ungulate exclosures. We measured seedling emergence because this stage is crucial in recruiting species into a community. We also measured light, water and standing crop biomass to test whether resource availability could help to explain seedling emergence rates.
Ungulates increased light availability for each sampling time and also increased above‐ground net primary productivity (ANPP) during summer.
Seedling emergence of rare prairie forbs and grasses was consistently greater when we added seeds.
Seedling emergence was conditionally greater with a combination of seed additions and grazing, but grazing alone was unable to increase emergence.
When ungulates increased seedling enhancement, the mechanism was partially associated with increased water and light availability.
Exotic and cosmopolitan weed seedling emergence was not affected by grazing.
Synthesis and applications. These results suggest that tallgrass prairie restorations are primarily seed limited and that grazing alone may not be able to increase seedling emergence of rare species without the addition of seeds. Therefore, adding seeds to grassland restorations may increase seedling emergence of rare species, and mimicking effects of grazing may increase emergence when seeds are added.
Ecologically justified charisma: preservation of top predators delivers biodiversity conservation
Authors: SERGIO FABRIZIO , NEWTON IAN , MARCHESI LUIGI , PEDRINI PAOLO 
Published: August 2006

Summary

Because of their popular appeal, top vertebrate predators have frequently been used as flagship or umbrella species to acquire financial support, raise environmental awareness and plan systems of protected areas. However, some have claimed that the utilization of charismatic predators may divert a disproportionate amount of funding to a few glamorous species without delivering broader biodiversity benefits, an accusation aggravated by the fact that the conservation of top predators is often complex, difficult and expensive. Therefore, tests are needed of whether apex predators may be employed to achieve ecosystem‐level targets.
To test such a hypothesis, we compared the biodiversity values recorded at the breeding sites of six raptor species, differing widely in diet and habitat associations, with those observed at three types of control locations, (i) sites randomly chosen in comparable habitat, (ii) breeding sites of a randomly selected bird species of lower trophic level and (iii) breeding sites of a lower trophic level species with specialized ecological requirements. Biodiversity was measured as the richness and evenness of bird, butterfly and tree species.
Biodiversity levels were consistently higher at sites occupied by top predators than at any of the three types of control sites. Furthermore, sites occupied by top predators also held greater densities of individual birds and butterflies (all species combined) than control sites.
In a reserve‐selection simulation exercise, networks of protected sites constructed on the basis of top predators were more efficient than networks based on lower trophic level species, enabling higher biodiversity coverage to be achieved with a smaller number of reserves.
Synthesis and applications. Our results provide evidence of a link between the strategic utilization of top predatory species and ecosystem‐level conservation. We suggest that, at least in some biological systems, conservation plans based on apex predators could be implemented to deliver broader biodiversity benefits.
Photon flux partitioning among species along a productivity gradient of an herbaceous plant community
Authors: AAN ANNE , HALLIK LEA , KULL OLEVI 
Published: August 2006

Summary

We studied light partitioning among species along the natural productivity gradient of herbaceous vegetation with an above‐ground dry mass of 150–490 g m−2. The aim was to investigate how the light capturing ability per above‐ground biomass and leaf nitrogen changes in an entire community and to reveal whether different species respond similarly to changes in soil conditions and competition.
Species becoming dominant at high soil resources have intrinsically low leaf area ratios (LAR) and lower tissue nitrogen concentration, and hence relatively high nitrogen use efficiency. These traits lead to dominance when soil resources allow rapid growth so that benefits arising from the ability to locate leaves above neighbours and thereby increasing asymmetry of competition, become more crucial.
In contrast to our expectations, above‐ground efficiency of nitrogen use on the community level (aNUE) increased along the productivity gradient. Species level nitrogen use efficiency was unaffected by variation in site productivity; the increase in community aNUE was solely as a consequence of changes in species composition.
Light absorption per unit of above‐ground mass, ΦM, declined significantly at the community level and also in most species, indicating that light use efficiency increased with increased site productivity and LAI.
Light absorption per unit of leaf nitrogen, ΦN, as an indicator of the ratio NUE/LUE showed no clear pattern on the community level because both NUE and LUE tend to increase with increased productivity. At the species level, ΦN tends to decrease because NUE did not change with stand productivity.
Some subordinate species responded by enlarging their LAR to increased competition. Additionally, these species were the most responsive in their leaf chlorophyll/nitrogen ratio to changes in light conditions, which shows that physiological plasticity is important for species that are unable to compete for light with the ability to position their leaves above those of other species.
This study shows how plasticity in above‐ground growth pattern and nitrogen allocation differs between species with respect to increased soil fertility and competition, leading to distinctive strategies of survival. Light partitioning analysis reveals that increased competition for light, resulting in changes in species composition, is the key factor that leads to decoupling of species and community level acclimation.
The rough edges of the conservation genetics paradigm for plants
Authors: OUBORG N. J. , VERGEER P. , MIX C. 
Published: August 2006

SummarySmall and isolated populations of species are susceptible to loss of genetic diversity, owing to random genetic drift and inbreeding. This loss of diversity may reduce the evolutionary potential to adapt to changing environments, and may cause immediate loss of fitness (cf. inbreeding depression). Together with other population size‐dependent stochastic processes, this may lead to increased probabilities of population extinction.This set of processes and theories forms the core of conservation genetics and has developed into the conservation genetics paradigm. Many empirical studies have concentrated on the relationship between population size and genetic diversity, and in many cases evidence was found that small populations of plants do indeed have lower levels of genetic diversity and increased homozygosity. Although less empirical attention has been given to the relationship between low genetic diversity, fitness and, in particular, evolutionary potential, the paradigm is now widely accepted.Here we present five areas of the paradigm which could be refined, i.e. the ‘rough’ edges of the conservation genetics paradigm.Treating population size and isolation not as interchangeable parameters but as separate parameters affecting population genetics in different ways could allow more accurate predictions of the effects of landscape fragmentation on the genetic diversity and viability of populations.There is evidence that inbreeding depression may be a genotype‐specific phenomenon, rather than a population parameter. This sheds new light on the link between population inbreeding depression and the expected increased probability of extinction.Modern eco‐genomics offers the opportunity to study the population genetics of functional genes, to the extent that the role of selection can be distinguished from the effects of drift, and allowing improved insights into the effects of loss of genetic diversity on evolutionary potential.Incorporating multispecies considerations may result in the generally accepted notion that small populations are at peril being called into question. For instance, small populations may be less capable of sustaining parasites or herbivores.Comparative studies of endangered, common and invasive species may be a valuable approach to developing conservation biology from a phenomenological case study discipline into one investigating the general principles of what sustains biodiversity.The issues discussed set an agenda for further research within conservation genetics and may lead to a further refinement of our understanding and prediction of the genetic effects of habitat fragmentation. They also underline the need to integrate ecological and genetic approaches to the conservation of biodiversity, rather than regarding them as opposites.
Elevated serum alkaline phosphatase levels in a renal transplant patient precede colitis
Authors: Korzets A. , Zevin D. , Ori Y. , Herman M. , Chagnac A. , Gafter U. 
Published: August 2006

Abstract: An asymptomatic, but highly significant, rise in serum alkaline phosphatase (AP) levels developed in a renal transplant recipient. Investigations ruled out bony or hepatobiliary disease. Subsequent diarrhea and weight loss led to a diagnosis of cytomegalovirus (CMV) colitis, which was confirmed with a positive CMV pp65 antigenemia test and an endoscopic finding of multiple colonic erosions. Intravenous ganciclovir led to complete patient recovery and a swift reduction of serum AP levels to normal.Normally, intestinal AP isoenzymes are cleared quickly from the circulation. However, acute bowel diseases, especially when inflammatory in origin, can produce high serum AP levels. In this presented patient, the rise in serum AP levels preceded symptomatic manifestations of CMV colitis, and fell with successful therapy.Acute CMV disease in solid organ transplant recipients is common, can take many shapes, and needs to be diagnosed quickly. An unexplained rise in serum AP levels should lead to a search for inflammatory bowel disease, specifically CMV colitis, in transplanted patients.
Mycobacterium tuberculosis infection following renal transplantation in Taiwan
Authors: Chen C.‐H. , Lian J.‐D. , Cheng C.‐H. , Wu M.‐J. , Lee W.‐C. , Shu K.‐H. 
Published: August 2006

Abstract: Background. Tuberculosis (TB) is one of the major causes of morbidity and mortality worldwide. Post‐transplant (post‐Tx) TB is a problem in successful long‐term outcome of renal transplantation recipients. It is a life‐threatening opportunistic infection that is frequently encountered, but the diagnosis is often delayed. With the emergence of newer potent immunosuppressive regimens and an increased incidence of TB in the general population, post‐Tx TB among transplant recipients can be anticipated. Our objective was to describe the pattern and risk factors of TB infection, and the prognosis in an endemic area.Methods. This study was a retrospective review of the records of 756 renal transplant recipients in our hospital during the period from January 1983 to December 2003. The demographic data, transplant characteristics, clinical manifestations, diagnostic criteria, treatment protocol, and long‐term outcome of this cohort of patients were analyzed.Results. Thirty‐one episodes developed into TB in 29 patients (3.8%) with a mean age of 45.5 (range: 24.2–66.2) years and a mean post‐Tx period of 57.9 (range: 1.2–145.2) months. The forms of the diseases were pulmonary in 22/31 (71%), disseminated in 1/31 (3%), miliary in 1/31 (3%), and extrapulmonary in 7/31 (23%). All patients initially received 4‐drug combination therapy, and then dosage was adjusted based on clinical condition. Because of drug interaction, a mean 2‐fold increase in the dose of calcineurium inhibitor, but no change in steroid, was required. Twenty‐two patients (71%) had an elevated creatinine (Cr) level, and 6 (19%) patients did not recover owing to tissue‐proof acute rejection (3 cases) and chronic allograft nephropathy (3 cases), respectively, after treatment. The serum Cr level on diagnosis of TB was 1.9±0.7 mg/dL; it then deteriorated to 2.4±1.5 mg/dL (P=0.134). Hepatotoxicity developed in 11 patients (35.5%) during treatment. Twenty‐five patients were successfully treated, 2 patients remain under treatment, and 4 (12.9%) died. Based on univariate analysis, we found the post‐Tx TB risk factors were diabetes and more than 3 episodes of rejection, modalities for acute rejection (high‐dose steroid and anti‐lymphocyte globulin), and maintenance therapy with steroid.Conclusion. Post‐Tx TB is a serious problem worldwide, and a high index of suspicion is warranted to ensure early diagnosis and prompt initiation of treatment for TB among renal transplant patients. The use of optimal immunosuppressive agents to minimize acute rejection seems reasonable to prevent TB infection in endemic areas like Taiwan. More than 9 months of treatment may be necessary to prevent recurrence.
Acute graft pyelonephritis following renal transplantation
Authors: Kamath N.S. , John G.T. , Neelakantan N. , Kirubakaran M.G. , Jacob C.K. 
Published: August 2006

Abstract: Background.Urinary tract infection is the most common form of bacterial infection encountered in a renal transplant recipient. Studies explaining the long‐term consequences of acute graft pyelonephritis (AGPN) are few.Methods.A total of 1022 consecutive renal allograft recipients were studied retrospectively over a period of 10 years for evidence of AGPN. These patients were classified into two groups according to the presence or absence of at least one AGPN episode. Only culture‐proven infections were included in the study.Result.Of the 1022 renal transplant recipients, 169 patients (16.5%) developed AGPN. In the multivariate analysis with stepwise logistic regression, significant associations were observed between AGPN and placement of ureteric stent (odds ratio [OR]=4.6), urological malformations of native kidney (OR=2.1), cytomegalovirus (CMV) disease (OR=2.0), mycophenolate mofetil (MMF)‐based regimen (OR=1.9), and acute rejection episodes (OR=1.5). However, age>40 years, female gender, induction therapy, anti‐CD3 treatment, and hyperglycemia did not show such an association. In comparison with the non‐AGPN group, these patients had a lower graft and patient survival (though it did not attain statistical significance). In the multivariate analysis using the Cox model for the entire study population, AGPN did not independently contribute to poor graft or patient survival.Conclusion.AGPN in the renal transplant setting is an ominous event, as these patients are also more prone to develop bacteremia, acute rejection, and CMV disease, which could then lead to poor graft and patient survival. Its association with MMF needs further clarification.
Experimental adaptation to high and low quality environments under different scales of temporal variation
Authors: BUCKLING A. , BROCKHURST M. A. , TRAVISANO M. , RAINEY P. B. 
Published: August 2006

AbstractWe investigated the role of the scale of temporal variation in the evolution of generalism in populations of the bacterium Pseudomonas fluorescens. Replicate populations were propagated as batch cultures for approximately 1400 generations (192 days), in either high quality media only, low quality media only, or were alternated between the two at a range of temporal scales (between 1 and 48 days). Populations evolved in alternating media showed fitness increases in both media and the rate of alternation during selection had no effect on average fitness in either media. Moreover, the fitness of these populations in high quality media was the same as for populations evolved only in high quality media and likewise for low quality media. Populations evolved only in high or low quality media did not show fitness improvements in their nonselective media. These results indicate that cost‐free generalists can evolve under a wide range of temporal variation.
Direct fitness or inclusive fitness: how shall we model kin selection?
Authors: TAYLOR P. D. , WILD G. , GARDNER A. 
Published: August 2006

AbstractTwo standard mathematical formulations of kin‐selection models can be found. Inclusive fitness is an actor‐centred approach, which calculates the fitness effect on a number of recipients of the behaviour of a single actor. Direct fitness is a recipient‐centred approach, which calculates the fitness effect on the recipient of the behaviour of a number of actors. Inclusive fitness offers us a powerful heuristic, of choosing behaviour to maximize fitness, but direct fitness can be mathematically easier to work with and has recently emerged as the preferred approach of theoreticians. In this paper, we explore the fundamental connection between these two approaches in both homogeneous and class‐structured populations, and we show that under simple assumptions (mainly fair meiosis and weak selection) they provide equivalent formulations, which correspond to the predictions of Price's equation for allele frequency change. We use a couple of examples to highlight differences in their conception and formulation, and we briefly discuss a two‐species example in which we have a class of ‘actor’ that is never a ‘recipient’, which the standard direct fitness method can handle but the usual inclusive fitness cannot.
Dynamics of the evolution of Batesian mimicry: molecular phylogenetic analysis of ant‐mimicking Myrmarachne (Araneae: Salticidae) species and their ant models
Authors: CECCARELLI F. S. , CROZIER R. H. 
Published: August 2006

AbstractBatesian mimicry is seen as an example of evolution by natural selection, with predation as the main driving force. The mimic is under selective pressure to resemble its model, whereas it is disadvantageous for the model to be associated with the palatable mimic. In consequence one might expect there to be an evolutionary arms race, similar to the one involving host–parasite coevolution. In this study, the evolutionary dynamics of a Batesian mimicry system of model ants and ant‐mimicking salticids is investigated by comparing the phylogenies of the two groups. Although Batesian mimics are expected to coevolve with their models, we found the phylogenetic patterns of the models and the mimics to be indicative of adaptive radiation by the mimic rather than co‐speciation between the mimic and the model. This shows that there is strong selection pressure on Myrmarachne, leading to a high degree of polymorphism. There is also evidence of sympatric speciation in Myrmarachne, the reproductive isolation possibly driven by female mate choice in polymorphic species.
Topiramate in the treatment of obese subjects with drug‐naive type 2 diabetes
Authors: Stenlöf K. , Rössner S. , Vercruysse F. , Kumar A. , Fitchet M. , Sjöström L. ,   Study Group
Published: August 2006

Aim: The aim of this study was to examine the efficacy and safety of topiramate as an adjunct to diet and exercise in drug‐naive, obese subjects with type 2 diabetes.Methods: Drug‐naive individuals with type 2 diabetes, body mass index (BMI) of ≥27 and <50 kg/m2and haemoglobin A1c(HbA1c) of <10.5% were enrolled into the study. All the individuals participated in a non‐pharmacologic weight loss program (Pathways to Change®; Johnson & Johnson Healthcare Systems, Piscataway, NJ, USA) throughout the trial. After a 6‐week placebo run‐in, the subjects were randomized to placebo, topiramate 96 mg/day or topiramate 192 mg/day. Subjects were scheduled for 8‐week titration and 52‐week maintenance phases. The study was ended early; efficacy data were reported for a predefined modified intent‐to‐treat (MITT) population (n = 229), with 40 weeks of treatment. All the subjects who provided any safety data were included in the safety population (n = 535).Results: Baseline mean weight was 103.7 kg, BMI 36 kg/m2and HbA1c6.7% across all treatment groups. By the end of week 40, the placebo, the topiramate 96 mg/day and topiramate 192 mg/day groups lost 2.5, 6.6 and 9.1% of their baseline body weight respectively (p < 0.001 vs. placebo, MITT population using last observation carried forward). The decrease in HbA1cwas 0.2, 0.6 and 0.7% respectively (p < 0.001 vs. placebo, MITT). Topiramate significantly reduced blood pressure and urinary albumin excretion; a weight‐loss‐independent HbA1cimproving effect of topiramate was demonstrated. Adverse events were predominantly related to central nervous system (CNS).Conclusions: Topiramate as an add‐on treatment to lifestyle improvements produced significant weight loss and improved glucose homeostasis in obese, drug‐naive subjects with type 2 diabetes. These treatment advantages should be balanced against the occurrence of adverse events in the CNS.