bluuebunny/crossref_metadata_2025 huggingface dataset:
Current approaches to obesity management in UK Primary Care: the Counterweight Programme
Authors:   The Counterweight Project Team
Published: December 2004

Background/Aims  Primary care is expected to develop strategies to manage obese patients as part of coronary heart disease and diabetes national service frameworks. Little is known about current management practices for obesity in this setting. The aim of this study is to examine current approaches to obesity management in UK primary care and to identify potential gaps in care.

Method  A total of 141 general practitioners (GPs) and 66 practice nurses (PNs) from 40 primary care practices participated in structured interviews to examine clinician self‐reported approaches to obesity management. Medical records were also reviewed for 100 randomly selected obese patients from each practice [body mass index (BMI) ≥30 kg m−2, n = 4000] to review rates of diet counselling, dietetic or obesity centre referrals, and use of anti‐obesity medication. Computerized medical records for the total practice population (n = 206 341, 18–75 years) were searched to examine the proportion of patients with a weight/BMI ever recorded.

Results  Eighty‐three per cent of GPs and 97% of PNs reported that they would raise weight as an issue with obese patients (P < 0.01). Few GPs (15%) reported spending up to 10 min in a consultation discussing weight‐related issues, compared with PNs (76%; P < 0.001). Over 18 months, practice‐based diet counselling (20%), dietetic (4%) and obesity centre (1%) referrals, and any anti‐obesity medication (2%) were recorded. BMI was recorded for 64.2% of patients and apparent prevalence of obesity was less than expected.

Conclusion  Obesity is under‐recognized in primary care even in these 40 practices with an interest in weight management. Weight management appears to be based on brief opportunistic intervention undertaken mainly by PNs. While clinicians report the use of external sources of support, few patients are referred, with practice‐based counselling being the most common intervention.
Old patients with hypertension. A 25‐year observational study of a geographically defined population (Dalby), aged 67 years at entry
Authors: Lidfeldt J. , Lanke J. , Sundquist J. , Lindholm L. H.
Published: December 2004

Abstract  Lidfeldt J, Lanke J, Sundquist J, Lindholm LH (Lund University, Lund, Sweden). Old patients with hypertension – a 25‐year observational study of a geographically defined population (Dalby), aged 67 years at entry. J Intern Med 1998; 244: 469–78.

Objectives.  To evaluate the impact of hypertension and other risk factors on mortality, in particular cardiovascular mortality, in a geographically defined population of elderly subjects.

Design.  An observational 25‐year study of a total population.

Setting.  The local health centre in the village of Dalby in southern Sweden.

Subjects.  All men and women born in 1902 or 1903, living in Dalby, were, at the age of 67, invited for medical and psychological examinations. The population comprised 188 subjects (109 men and 79 women); 156 (83%) of them took part in the first medical examination. Blood pressure, heart rate, weight and height were measured and laboratory tests performed at entry. Blood pressures were thereafter recorded six times, and this report is based on a 25‐year follow‐up period ending in October 1994.

Main outcome measures.  Survival analyses were performed, based on definition of underlying causes of death, divided into all‐cause and cardiovascular.

Results.  At entry, females had higher blood pressure than males, both at baseline and during the first 16 years of the study, regardless of whether they were hypertensives or not. Most men smoked but only a few women. At the end of the follow‐up of the present study in 1994, 138 out of 156 (88%) subjects had died and only 18 (12%) remained alive; 78 (57%) had died of a cardiovascular disease. In men, a diagnosis of hypertension as well as increased blood pressure at entry was associated with increased mortality. In women this was the case for blood pressure and risk of cardiovascular mortality. In men, both systolic and diastolic blood pressures during the study were significant risk factors for death, whereas in women this was not the case.

Conclusions.  Elderly male hypertensives ran an increased mortality risk even though they were treated according to the then current guidelines; female hypertensives seemed to run the same risk of dying as normotensive females.
Assessing the effectiveness and cost‐effectiveness of prophylaxis against bleeding in patients with severe haemophilia and severe von Willebrand's disease
Authors: Miners A. H. , Sabin C. A. , Tolley K. H. , Lee C. A.
Published: December 2004

Abstract. Miners AH, Sabin CA, Tolley KH, Lee CA (Royal Free Hospital School of Medicine, London; University Hospital Queen's Medical Centre, Nottingham; and Royal Free Hampstead NHS Trust, London, UK). Assessing the effectiveness and cost‐effectiveness of prophylaxis against bleeding in patients with severe haemophilia and severe von Willebrand's disease. J Intern Med 1998; 244: 515–22.

Objectives To assess the effectiveness and cost‐effectiveness of prophylaxis with clotting factor against bleeding in patients with severe haemophilia and von Willebrand's disease (vWD).

Design Treatment details that related to 179 patients with severe (< 1 u dL−1) haemophilia A, B and vWD were retrospectively examined for the period 1980–95. A subgroup of these patients, 25 adults and 22 children, who had previously received treatment on demand and who had switched to treating with prophylaxis, were studied in order to examine the effects of the change. The cost‐effectiveness of prophylaxis was also analysed using another subgroup of 38 patients and by adjusting their treatment details by age and method of treatment.

Setting Data were obtained on patients who were solely registered at the Royal Free Hospital Haemophilia Centre (RFHHC), London, UK.

Outcome measure Bleeds.

Results The median annual number of bleeds decreased from 23.5 (range 1–107) in 1980, to 14 (range 0–45) in 1995 (P < 0.0001). Switching from treating on demand to prophylaxis reduced bleeding frequency in 41 out of 47 patients within the period of 1 year. At the base scenario, switching to prophylaxis cost an additional £547 per averted bleed; however, this figure was highly sensitive to certain variables.

Conclusion Prophylaxis can reduce bleeding frequency but requires more clotting factor than treatment on demand. More detailed proof of cost‐effectiveness is likely to require the use of modelling techniques.
Life events and neurocirculatory asthenia. A controlled study
Authors: Sonino N. , Fava G. A. , Fava G. A. , Boscaro M. , Fallo F.
Published: December 2004

Sonino N, Fava GA, Boscaro M, Fallo F (University of Padova, Padova, University of Bologna, Bologna, Italy; and State University of New York at Buffalo, NY USA). Life events and neurocirculatory asthenia. A controlled study. J Intern Med 1998; 244: 523–8.

Objectives : The purpose of this study was to assess the occurrence of stressful life events in the year before the onset of neurocirculatory asthenia.

Design : Case‐control retrospective study.

Setting : A university medical outpatient clinic.

Subjects : A consecutive series of 50 patients with neurocirculatory asthenia and a control group of 50 healthy subjects, matched for sociodemographic variables, were studied.

Main outcome measures : Paykel's Interview for Recent Life Events (a semistructured research interview covering 64 life events) was administered to patients and controls.

Results : Patients with neurocirculatory asthenia reported significantly more stressful life events than the control group (P < 0.05) and had significantly more of the following: exits (P < 0.05), undesirable (P < 0.05) and uncontrolled (P < 0.01) events. More events that had an objective negative impact (P < 0.001) and more independent events (P = 0.07) were also reported. Ratings of impact and independence were carried out by a blind rater who was unaware whether the event had occurred in patients or controls.

Conclusions : The results are suggestive of a strong relationship between stressful life events and neurocirculatory asthenia. This is in agreement with a multifactorial model of pathogenesis in neurocirculatory asthenia and with current understanding of the extensive links of behavioral responses to stress with neurophysiological and biochemical processes.
Planning of clinical trials
Authors: Boissel J.‐P.
Published: December 2004

This article focuses on steps of planning clinical trials most relevant to the question the clinician asks and how this question is properly transformed in a design and a protocol. All steps are important for the data quality or the validity of the results. A clinical trial is an experiment aimed at testing an hypothesis regarding the efficacy of a given intervention on an event, symptom or impaired quality of life in patients with a defined condition and a particular profile. As such, it should meet the fundamentals of scientific discovery that guarantee causality between the observed difference and the intervention. All the planning components are thought according to these fundamentals.
Undertreatment and overtreatment with statins: the Oslo Health Study 2000–2001
Authors: Tonstad S. , Rosvold E. O. , Furu K. , Skurtveit S.
Published: December 2004

Objective.  We examined the prevalence and factors associated with use of cholesterol‐lowering statins in the population.

Methods.  Demographic, medical, anthropometric and lifestyle data was obtained from 6233 men and 7521 women born in 1924/25, 1940/41, 1955 and 1960 that participated in the Oslo Health Study 2000–2001. A nonfasting blood sample was collected.

Results.  Of subjects with a heart attack, angina, stroke or diabetes 45% of men and 35% of women were taking a statin (P < 0.001). Of subjects with cardiovascular disease (CVD) or diabetes taking statins 61% of men and 40% of women achieved total serum cholesterol levels ≤5 mmol L−1. The odds ratio for taking a statin was increased amongst subjects who also took antihypertensive drug(s) or acetylsalicylic acid, subjects with a family history of coronary heart disease (CHD) and women who had visited the general practitioner within the last year. Amongst presumed healthy subjects use of statins increased from about 1% in women aged 40–45 years, to 7% at age 60 and to 12% at age 75 whilst the corresponding figures for men were 3%, 8% and 9%, respectively. About 22% of men but <2% of women aged 60 who were not taking statins had a 10‐year Framingham CHD risk score >20%. Determinants of statin use were similar to those amongst subjects with CVD or diabetes.

Conclusion.  People with CVD or diabetes remain undertreated with statins, women more so than men. Use of other preventive drugs, the family history and recent contact with the general practitioner were the most important determinants of statin use in primary and secondary prevention. Amongst healthy subjects aged 60 or 75 years women received statins disproportionately to their low CHD risk compared with men.
On the evolution of statistical methods as applied to clinical trials
Authors: Machin D.
Published: December 2004

This paper describes how statistical methods have evolved in parallel with activities associated with randomized control trials. In particular we emphasize the pivotal role of two papers published inBritish Journal of Cancer, and the paper describing the Cox proportional hazards model. In addition, the importance of early papers on estimating the sample size required for trials is highlighted. Later developments including the increasing roles for competing risks, multilevel modelling and Bayesian methodologies are described. The interplay between computer software and statistical methodological developments is stressed. Finally some future directions are indicated.
Prognostic value of biochemical markers, 12‐lead ECG and patient characteristics amongst patients calling for an ambulance due to a suspected acute coronary syndrome
Authors: Svensson L. , Axelsson C. , Nordlander R. , Herlitz J.
Published: December 2004

Objectives.  To evaluate whether a 12‐lead ECG, together with a multi‐marker strategy that used point‐of‐care measurements of myoglobin, creatine kinase (CK‐MB) and troponin I, was able to predict patients at short‐ and long‐term risk of death, when simultaneously considering age, gender, previous history, symptoms and clinical findings on arrival of the ambulance.

Design.  Prospective observational study.

Setting and subjects.  Consecutive patients (n=511) in ambulances in Stockholm and Göteborg in Sweden who called for an ambulance due to chest pain or other symptoms raising a suspicion of acute coronary syndrome.

Intervention.  In almost all patients, a diagnostic ECG, patient baseline characteristics and measurements of CK‐MB, troponin I and myoglobin were recorded.

Results.  In univariate analysis, the highest 30‐day mortality (17%) was found amongst patients with the combination of ECG signs of myocardial ischaemia and the elevation of any biochemical marker. The highest 1‐year mortality (20%) was found amongst patients with ECG signs of myocardial ischaemia and the elevation of any biochemical marker. Increasing age (RR 1.07; 95 CI 1.02–1.13) lack of symptoms of chest pain and a previous history of hypertension (3.02; 1.08–8.79) were independent predictors of 30‐day mortality. Myoglobin was the only biochemical marker independently associated with 30‐day mortality (6.66; 1.83–22.3). Increasing age (1.11; 1.06–1.16), previous history of diabetes (3.42; 1.41–8.25) heart failure (2.64; 1.26–5.52) and other symptoms than chest pain and dyspnoea (5.23; 2.14–12.76) were independent predictors of 1‐year mortality. In many of the variables the confidence limits were wide.

Conclusion.  Amongst patients with a clinical suspicion of acute coronary syndrome, those with the combination of ECG signs of myocardial ischaemia and the elevation of any biochemical marker on arrival of the ambulance form a group with a particularly high risk of death. However, age as well as aspects of clinical history and type of symptoms independently contribute to prognostic information.
Cost‐effectiveness of clopidogrel in acute coronary syndromes in Sweden: a long‐term model based on the cure trial
Authors: Lindgren P. , Jönsson B. , Yusuf S.
Published: December 2004

Objectives.  The purpose of this study was to evaluate the long‐term cost‐effectiveness of clopidogrel on top of standard therapy (including ASA) in patients with acute coronary syndromes without ST‐segment elevation in Sweden.

Methods and results.  Incremental cost‐effectiveness ratios (ICER) were assessed using a Markov model with transition probabilities estimated from the Swedish hospital discharge and cause of death registers. Patients were assumed to be treated for 1 year, with treatment effects (RR = 0.8) and costs taken from the Clopidogrel in Unstable Angina to prevent Recurrent ischaemic Events trial. Two scenarios were analysed: with patients similar to those in the trial and with patients similar to those from the register. In the first scenario, the predicted net direct cost was 160€ and the net total cost −54€, which with an incremental survival of 0.12 years give the ICER of 1365€ per life‐year gained from the health care payer perspective (including direct costs) and cost savings from the societal perspective (also including indirect costs). The net costs in the second scenario were 149€, giving an ICER of 1009€ for both perspectives.

Conclusions.  Adding clopidogrel to standard therapy including ASA is cost‐effective in the studied setting and compares favourably with other cardiovascular treatment and prevention strategies.
Bayesian approaches for the analysis of population genetic structure: an example fromPlatanthera leucophaea(Orchidaceae)
Authors: Holsinger Kent E. , Wallace Lisa E.
Published: December 2004

We describe four extensions to existing Bayesian methods for the analysis of genetic structure in populations: (i) use of beta distributions to approximate the posterior distribution offand θB; (ii) use of an entropy statistic to describe the amount of information about a parameter derived from the data; (iii) use of the Deviance Information Criterion (DIC) as a model choice criterion for determining whether there is evidence for inbreeding within populations or genetic differentiation among populations; and (iv) use of samples from the posterior distributions forfand θBderived from different data sets to determine whether the estimates are consistent with one another. We illustrate each of these extensions by applying them to data derived from previous alloyzme and random amplified polymorphic DNA surveys of an endangered orchid,Platanthera leucophaea, and we conclude that differences in θBfrom the two data sets may represent differences in the underlying mutational processes.
Effect of unsampled populations on the estimation of population sizes and migration rates between sampled populations
Authors: Beerli Peter
Published: December 2004

Current estimators of gene flow come in two methods; those that estimate parameters assuming that the populations investigated are a small random sample of a large number of populations and those that assume that all populations were sampled. Maximum likelihood or Bayesian approaches that estimate the migration rates and population sizes directly using coalescent theory can easily accommodate datasets that contain a population that has no data, a so‐called ‘ghost’ population. This manipulation allows us to explore the effects of missing populations on the estimation of population sizes and migration rates between two specific populations. The biases of the inferred population parameters depend on the magnitude of the migration rate from the unknown populations. The effects on the population sizes are larger than the effects on the migration rates. The more immigrants from the unknown populations that are arriving in the sample populations the larger the estimated population sizes. Taking into account a ghost population improves or at least does not harm the estimation of population sizes. Estimates of the scaled migration rateM(migration rate per generation divided by the mutation rate per generation) are fairly robust as long as migration rates from the unknown populations are not huge. The inclusion of a ghost population does not improve the estimation of the migration rateM; when the migration rates are estimated as the number of immigrants Nm then a ghost population improves the estimates because of its effect on population size estimation. It seems that for ‘real world’ analyses one should carefully choose which populations to sample, but there is no need to sample every population in the neighbourhood of a population of interest.
Evaluating the performance of likelihood methods for detecting population structure and migration
Authors: Abdo ZAID , Crandall Keith A. , Joyce PAUL
Published: December 2004

A plethora of statistical models have recently been developed to estimate components of population genetic history. Very few of these methods, however, have been adequately evaluated for their performance in accurately estimating population genetic parameters of interest. In this paper, we continue a research program of evaluation of population genetic methods through computer simulation. Specifically, we examine the software migratee‐n 1.6.8 and test the accuracy of this software to estimate genetic diversity (Θ), migration rates, and confidence intervals. We simulated nucleotide sequence data under a neutral coalescent model with lengths of 500 bp and 1000 bp, and with three different per site Θ values of (0.00025, 0.0025, 0.025) crossed with four different migration rates (0.0000025, 0.025, 0.25, 2.5) to construct 1000 evolutionary trees per‐combination per‐sequence‐length. We found that while migratee‐n 1.6.8 performs reasonably well in estimating genetic diversity (Θ), it does poorly at estimating migration rates and the confidence intervals associated with them. We recommend researchers use this software with caution under conditions similar to those used in this evaluation.
Microsatellite variation and population structure in a declining Australian HylidLitoria aurea
Authors: Burns Emma L. , Eldridge Mark D. B. , Houlden Bronwyn A.
Published: December 2004

The green and golden bell frog (Litoria aurea) was once a common Australian Hylid. Today, many populations are small and fragmented as a result of dramatic declines in distribution and abundance. We undertook a large‐scale assessment of genetic structure and diversity inL. aureausing four species‐specific microsatellite markers. Twenty‐one locations were sampled from throughout the species range covering 1000 km of the east coast of Australia. Levels of allelic diversity and heterozygosity were high (uncorrected mean alleles/locus andHEwere 4.8–8.8 and 0.43–0.8, respectively) compared to other amphibian species and significant differences among sampled sites were recorded. Despite recent population declines, no sites displayed a genetic signature indicative of a population bottleneck. Significant genetic structuring (overallFST0.172) was detected throughout the species range, but was relatively low compared to previous amphibian studies employing microsatellites. In addition we found that some areas sampled within continuous habitat showed evidence of weak genetic structuring (data subsetFST0.034). We conclude that maintaining areas of continuous habitat is critical to the conservation of the species and argue that population recovery and/or persistence in all areas sampled is possible if appropriate protection and management are afforded.
‘O father: where art thou?’— Paternity assessment in an open fission–fusion society of wild bottlenose dolphins (Tursiopssp.) in Shark Bay, Western Australia
Authors: Krützen Michael , Barré Lynne M. , Connor Richard C. , Mann Janet , Sherwin William B.
Published: December 2004

Sexually mature male bottlenose dolphins in Shark Bay cooperate by pursuing distinct alliance strategies to monopolize females in reproductive condition. We present the results of a comprehensive study in a wild cetacean population to test whether male alliance membership is a prerequisite for reproductive success. We compared two methods for inferring paternity: both calculate a likelihood ratio, called the paternity index, between two opposing hypotheses, but they differ in the way that significance is applied to the data. The first method, a Bayesian approach commonly used in human paternity testing, appeared to be overly conservative for our data set, but would be less susceptible to assumptions if a larger number of microsatellite loci had been used. Using the second approach, the computer programcervus2.0, we successfully assigned 11 paternities to nine males, and 17 paternities to 14 out of 139 sexually mature males at 95% and 80% confidence levels, respectively. It appears that being a member of a bottlenose dolphin alliance is not a prerequisite for paternity: two paternities were obtained by juvenile males (one at the 95%, the other at the 80% confidence level), suggesting that young males without alliance partners pursue different mating tactics to adults. Likelihood analyses showed that these two juvenile males were significantly more likely to be the true father of the offspring than to be their half‐sibling (P < 0.05). Using paternity data at an 80% confidence level, we could show that reproductive success was significantly skewed within at least some stable first‐order alliances (P < 0.01). Interestingly, there is powerful evidence that one mating was incestuous, with one calf apparently fathered by its mother's father (P < 0.01). Our study suggests that the reproductive success of both allied males, and of nonallied juveniles, needs to be incorporated into an adaptive framework that seeks to explain alliance formation in male bottlenose dolphins.
Very low genetic variability in the Indian queenless ant Diacamma indicum
Authors: Viginier B. , Peeters C. , Brazier L. , Doums C.
Published: December 2004

We developed microsatellite markers and combined them with mitochondrial markers to analyse the population genetic structure of the queenless ant Diacamma indicum. This species, lacking winged queens, is likely to have a restricted female dispersal but exhibits various life history traits suggesting higher dispersal abilities than the other Diacamma species. Only 4 of 11 microsatellites were polymorphic and only 1 had more than 4 alleles over 166 individuals originating from 7 populations from the south of India. Only one mitochondrial DNA (mtDNA) haplotype was detected throughout India (including one population in the north) and Sri Lanka. Such a level of polymorphism is particularly low compared with other Diacamma species having much smaller ranges in the south of India. A strong genetic differentiation was observed between populations separated by more than a few kilometres. We also analysed the genetic differentiation between the Indian populations and two populations from the Japanese island of Okinawa, which are morphologically similar and might belong to the same species. The genetic differentiation was high for both markers, suggesting an absence of ongoing gene flow between these populations.
Distribution of the bacterial symbiont Cardinium in arthropods
Authors: ZCHORI‐FEIN EINAT , PERLMAN STEVE J.
Published: December 2004

‘Candidatus Cardinium’, a recently described bacterium from the Bacteroidetes group, is involved in diverse reproduction alterations of its arthropod hosts, including cytoplasmic incompatibility, parthenogenesis and feminization. To estimate the incidence rate of Cardinium and explore the limits of its host range, 99 insect and mite species were screened, using primers designed to amplify a portion of Cardinium 16S ribosomal DNA (rDNA). These arthropods were also screened for the presence of the better‐known reproductive manipulator, Wolbachia. Six per cent of the species screened tested positive for Cardinium, compared with 24% positive for Wolbachia. Of the 85 insects screened, Cardinium was found in four parasitic wasp species and one armoured scale insect. Of the 14 mite species examined, one predatory mite was found to carry the symbiont. A phylogenetic analysis of all known Cardinium 16S rDNA sequences shows that distantly related arthropods can harbour closely related symbionts, a pattern typical of horizontal transmission. However, closely related Cardinium were found to cluster among closely related hosts, suggesting host specialization and horizontal transmission among closely related hosts. Finally, the primers used revealed the presence of a second lineage of Bacteroidetes symbionts, not related to Cardinium, in two insect species. This second symbiont lineage is closely allied with other arthropod symbionts, such as Blattabacterium, the primary symbionts of cockroaches, and male‐killing symbionts of ladybird beetles. The combined data suggest the presence of a diverse assemblage of arthropod‐associated Bacteroidetes bacteria that are likely to strongly influence their hosts’ biology.
Population genetics of the roan antelope (Hippotragus equinus) with suggestions for conservation
Authors: ALPERS D. L. , VAN VUUREN B. J. , ARCTANDER P. , ROBINSON T. J.
Published: December 2004

The roan antelope (Hippotragus equinus) is the second largest African antelope, distributed throughout the continent in sub‐Saharan savannah habitat. Mitochondrial DNA (mtDNA) control region sequencing (401 bp, n = 137) and microsatellite genotyping (eight loci, n = 137) were used to quantify the genetic variability within and among 18 populations of this species. The within‐population diversity was low to moderate with an average mtDNA nucleotide diversity of 1.9% and average expected heterozygosity with the microsatellites of 46%, but significant differences were found among populations with both the mtDNA and microsatellite data. Different levels of genetic resolution were found using the two marker sets, but both lent strong support for the separation of West African populations (samples from Benin, Senegal and Ghana) from the remainder of the populations studied across the African continent. Mismatch distribution analyses revealed possible past refugia for roan in the west and east of Africa. The West African populations could be recognized together as an evolutionarily significant unit (ESU), referable to the subspecies H. e. koba. Samples from the rest of the continent constituted a geographically more diverse assemblage with genetic associations not strictly corresponding to the other recognized subspecies.
Factors affecting the amount of genomic DNA extracted from ape faeces and the identification of an improved sample storage method
Authors: NSUBUGA A. M. , ROBBINS M. M. , ROEDER A. D. , MORIN P. A. , BOESCH C. , VIGILANT L.
Published: December 2004

Genetic analysis using noninvasively collected samples such as faeces continues to pose a formidable challenge because of unpredictable variation in the extent to which usable DNA is obtained. We investigated the influence of multiple variables on the quantity of DNA extracted from faecal samples from wild mountain gorillas and chimpanzees. There was a small negative correlation between temperature at time of collection and the amount of DNA obtained. Storage of samples either in RNAlater solution or dried using silica gel beads produced similar results, but significantly higher amounts of DNA were obtained using a novel protocol that combines a short period of storage in ethanol with subsequent desiccation using silica.
Isolation by distance and sharp discontinuities in gene frequencies: implications for the phylogeography of an alpine insect species, Carabus solieri
Authors: GARNIER S. , ALIBERT P. , AUDIOT P. , PRIEUR B. , RASPLUS J.‐Y.
Published: December 2004

Analysis of genetic isolation by distance (IBD) is of prime importance for the study of processes responsible for spatial population genetic structure and is thus frequently used in case studies. However, the identification of a significant IBD pattern does not necessarily imply the absence of sharp discontinuities in gene frequencies. Therefore, identifying barriers to gene flow and/or secondary contact between differentiated entities remains a major challenge in population biology. Geographical genetic structure of 41 populations (1080 individuals) of an alpine insect species, Carabus solieri, was studied using 10 microsatellite loci. All populations were significantly differentiated and spatially structured according to IBD over the entire range. However, clustering analyses clearly identified three main clusters of populations, which correspond to geographical entities. Whereas IBD also occurs within each cluster, population structure was different according to which group of populations was considered. The southernmost cluster corresponds to the most fragmented part of the range. Consistently, it was characterized by relatively high levels of differentiation associated with low genetic diversity, and the slope of the regression of genetic differentiation against geographical distances was threefold those of the two other clusters. Comparisons of within‐cluster and between‐cluster IBD patterns revealed barriers to gene flow. A comparison of the two approaches, IBD and clustering analyses, provided us with valuable information with which to infer the phylogeography of the species, and in particular to propose postglacial colonization routes from two potential refugia located in Italy and in southeastern France. Our study highlights strongly the possible confounding contribution of barriers to gene flow to IBD pattern and emphasizes the utility of the model‐based clustering analysis to identify such barriers.
Phylogeographic structure, gene flow and species status in blue grouse (Dendragapus obscurus)
Authors: BARROWCLOUGH GEORGE F. , GROTH JEFF G. , MERTZ LISA A. , GUTIÉRREZ R. J.
Published: December 2004

We investigated the genetic population structure and species status of a relatively sedentary bird that is a permanent resident of western North American forests, the blue grouse (Dendragapus obscurus). Phylogenetic analysis of complete mitochondrial control region DNA sequences resulted in the identification of three basal clades of haplotypes that were largely congruent with well‐known biogeographical regions. These clades corresponded to the parapatric sooty (D. o. fuliginosus) and dusky (D. o. obscurus) subspecies groups of blue grouse plus a previously unrecognized division between northern and southern dusky grouse populations; the latter does not correspond closely to any currently recognized subspecies boundary. Approximately 66% of the total genetic variation was distributed among these three regions. Maximum likelihood estimates of gene flow between the regions were low or asymmetric; gene flow has been insufficient to prevent genetic divergence between dusky and sooty grouse. Estimates of gene flow among populations within sooty grouse were large except across the Columbia River valley. Among populations of dusky grouse, estimates of gene flow were heterogeneous and asymmetrical, reflecting large‐scale fragmentation of the distribution due to landscape features and associated vegetation. Genetic, morphological and behavioural evidence suggest that sooty and dusky grouse are species‐level taxa; the specific status of a third clade remains ambiguous.
Population structure of loggerhead shrikes in the California Channel Islands
Authors: EGGERT LORI S. , MUNDY NICHOLAS I. , WOODRUFF DAVID S.
Published: December 2004

The loggerhead shrike (Lanius ludovicianus), a songbird that hunts like a small raptor, maintains breeding populations on seven of the eight California Channel Islands. One of the two subspecies, L. l. anthonyi, was described as having breeding populations on six of the islands while a second subspecies, L. l. mearnsi, was described as being endemic to San Clemente Island. Previous genetic studies have demonstrated that the San Clemente Island loggerhead shrike is well differentiated genetically from both L. l. anthonyi and mainland populations, despite the fact that birds from outside the population are regular visitors to the island. Those studies, however, did not include a comparison between San Clemente Island shrikes and the breeding population on Santa Catalina Island, the closest island to San Clemente. Here we use mitochondrial control region sequences and nuclear microsatellites to investigate the population structure of loggerhead shrikes in the Channel Islands. We confirm the genetic distinctiveness of the San Clemente Island loggerhead shrike and, using Bayesian clustering analysis, demonstrate the presence and infer the source of the nonbreeding visitors. Our results indicate that Channel Island loggerhead shrikes comprise three distinct genetic clusters that inhabit: (i) San Clemente Island, (ii) Santa Catalina Island and (iii) the Northern Channel Islands and nearby mainland; they do not support a recent suggestion that all Channel Island loggerhead shrikes should be managed as a single entity.
The effect of the last glacial age on speciation and population genetic structure of the endangered Ethiopian wolf (Canis simensis)
Authors: GOTTELLI DADA , MARINO JORGELINA , SILLERO‐ZUBIRI CLAUDIO , FUNK STEPHAN M.
Published: December 2004

During the last glacial age, Afro‐alpine habitats were widespread across the highlands of Ethiopia. A wolf‐like canid ancestor is thought to have colonized this expanding habitat and given rise to a new species that was remarkably well adapted to the high altitude environment: the Ethiopian wolf Canis simensis. Here, we address the timing of genetic divergence and examine population genetic history and structure by investigating the distribution of mitochondrial DNA (mtDNA) sequence variation. The pattern of mtDNA variation and geographical distribution indicate an initial population expansion, probably immediately after divergence from the wolf‐like ancestor, around 100 000 years ago. The partition of mtDNA haplotypes that followed was most likely the result of habitat reduction and fragmentation at the onset of deglaciation ~ 15 000 years ago. Phylogenetic and geographical associations suggest that the most likely genetic partitioning corresponds to three mountain areas, Arsi/Bale, Wollo/Shoa and Simien/Mt. Guna. Although there is a degree of clustering of haplotypes from both sides of the Rift Valley, the lack of reciprocal monophyly does not support the taxonomic classification of two subspecies. This study highlights the importance of populations north of the Rift Valley for the maintenance of genetic variability within the species and has consequent implications for conservation.
Global population structure and taxonomy of the wandering albatross species complex
Authors: BURG T. M. , CROXALL J. P.
Published: December 2004

A recent taxonomic revision of wandering albatross elevated each of the four subspecies to species. We used mitochondrial DNA and nine microsatellite markers to study the phylogenetic relationships of three species (Diomedea antipodensis, D. exulans and D. gibsoni) in the wandering albatross complex. A small number of samples from a fourth species, D. dabbenena, were analysed using mitochondrial DNA only. Mitochondrial DNA sequence analyses indicated the presence of three distinct groups within the wandering albatross complex: D. exulans, D. dabbenena and D. antipodensis/D. gibsoni. Although no fixed differences were found between D. antipodensis and D. gibsoni, a significant difference in the frequency of a single restriction site was detected using random fragment length polymorphism. Microsatellite analyses using nine variable loci, showed that D. exulans, D. antipodensis and D. gibsoni were genetically differentiated. Despite the widespread distribution of D. exulans, we did not detect any genetic differentiation among populations breeding on different island groups. The lower level of genetic differentiation between D. antipodensis and D. gibsoni should be reclassified as D. antipodensis. Within the context of the current taxonomy, these combined data support three species: D. dabbenena, D. exulans and D. antipodensis.
Genetic diversity and population structure of Tasmanian devils, the largest marsupial carnivore
Authors: JONES MENNA E. , PAETKAU DAVID , GEFFEN ELI , MORITZ CRAIG
Published: December 2004

Genetic diversity and population structure were investigated across the core range of Tasmanian devils (Sarcophilus laniarius; Dasyuridae), a wide‐ranging marsupial carnivore restricted to the island of Tasmania. Heterozygosity (0.386–0.467) and allelic diversity (2.7–3.3) were low in all subpopulations and allelic size ranges were small and almost continuous, consistent with a founder effect. Island effects and repeated periods of low population density may also have contributed to the low variation. Within continuous habitat, gene flow appears extensive up to 50 km (high assignment rates to source or close neighbour populations; nonsignificant values of pairwise FST), in agreement with movement data. At larger scales (150–250 km), gene flow is reduced (significant pairwise FST) but there is no evidence for isolation by distance. The most substantial genetic structuring was observed for comparisons spanning unsuitable habitat, implying limited dispersal of devils between the well‐connected, eastern populations and a smaller northwestern population. The genetic distinctiveness of the northwestern population was reflected in all analyses: unique alleles; multivariate analyses of gene frequency (multidimensional scaling, minimum spanning tree, nearest neighbour); high self‐assignment (95%); two distinct populations for Tasmania were detected in isolation by distance and in Bayesian model‐based clustering analyses. Marsupial carnivores appear to have stronger population subdivisions than their placental counterparts.
Climate and habitat barriers to dispersal in the highly mobile grey wolf
Authors: GEFFEN ELI , ANDERSON MARTI J. , WAYNE ROBERT K.
Published: December 2004

We reanalysed published data to evaluate whether climate and habitat are barriers to dispersal in one of the most mobile and widely distributed mammals, the grey wolf (Canis lupus). Distance‐based redundancy analysis (dbRDA) was used to examine the amount of variation in genetic distances that could be explained by an array of environmental factors, including geographical distance. Patterns in genetic variation were also examined using MDS plots among populations and relationships between genetic structure and individual environmental variables were further explored using the BIOENV procedure. We found that, contrary to a previous report, a pattern of isolation with distance is evident on a continental scale in the North American wolf population. This pattern is apparently related to climate and habitat. Specifically, vegetation types appear to play a role in the genetic dissimilarities among populations. When we controlled for the effect of spatial variation, climate was still associated with genetic distance. Further, partitioning of geographical distances into latitudinal and longitudinal axes revealed that the east–west gradient had the strongest relationship with genetic distance. We suggest two possible mechanisms by which environmental conditions may influence the dispersal decisions made by wolves.
Diversity and specificity of Rhizobium leguminosarum biovar viciae on wild and cultivated legumes
Authors: MUTCH LESLEY A. , YOUNG J. PETER W.
Published: December 2004

The symbiotic partnerships between legumes and their root‐nodule bacteria (rhizobia) vary widely in their degree of specificity, but the underlying reasons are not understood. To assess the potential for host‐range evolution, we have investigated microheterogeneity among the shared symbionts of a group of related legume species. Host specificity and genetic diversity were characterized for a soil population of Rhizobium leguminosarum biovar viciae (Rlv) sampled using six wild Vicia and Lathyrus species and the crop plants pea (Pisum sativum) and broad bean (Vicia faba). Genetic variation among 625 isolates was assessed by restriction fragment length polymorphism (RFLP) of loci on the chromosome (ribosomal gene spacer) and symbiosis plasmid (nodD region). Broad bean strongly favoured a particular symbiotic genotype that formed a distinct phylogenetic subgroup of Rlv nodulation genotypes but was associated with a range of chromosomal backgrounds. Host range tests of 80 isolates demonstrated that only 34% of isolates were able to nodulate V. faba. By contrast, 89% were able to nodulate all the local wild hosts tested, so high genetic diversity of the rhizobial population cannot be ascribed directly to the diversity of host species at the site. Overall the picture is of a population of symbionts that is diversified by plasmid transfer and shared fairly indiscriminately by local wild legume hosts. The crop species are less promiscuous in their interaction with symbionts than the wild legumes.
Rivers influence the population genetic structure of bonobos (Pan paniscus)
Authors: ERIKSSON J. , HOHMANN G. , BOESCH C. , VIGILANT L.
Published: December 2004

Bonobos are large, highly mobile primates living in the relatively undisturbed, contiguous forest south of the Congo River. Accordingly, gene flow among populations is assumed to be extensive, but may be impeded by large, impassable rivers. We examined mitochondrial DNA control region sequence variation in individuals from five distinct localities separated by rivers in order to estimate relative levels of genetic diversity and assess the extent and pattern of population genetic structure in the bonobo. Diversity estimates for the bonobo exceed those for humans, but are less than those found for the chimpanzee. All regions sampled are significantly differentiated from one another, according to genetic distances estimated as pairwise FSTs, with the greatest differentiation existing between region East and each of the two Northern populations (N and NE) and the least differentiation between regions Central and South. The distribution of nucleotide diversity shows a clear signal of population structure, with some 30% of the variance occurring among geographical regions. However, a geographical patterning of the population structure is not obvious. Namely, mitochondrial haplotypes were shared among all regions excepting the most eastern locality and the phylogenetic analysis revealed a tree in which haplotypes were intermixed with little regard to geographical origin, with the notable exception of the close relationships among the haplotypes found in the east. Nonetheless, genetic distances correlated with geographical distances when the intervening distances were measured around rivers presenting effective current–day barriers, but not when straight‐line distances were used, suggesting that rivers are indeed a hindrance to gene flow in this species.
Chloroplast DNA variation and postglacial recolonization of common ash (Fraxinus excelsior L.) in Europe
Authors: HEUERTZ M. , FINESCHI S. , ANZIDEI M. , PASTORELLI R. , SALVINI D. , PAULE L. , FRASCARIA‐LACOSTE N. , HARDY O. J. , VEKEMANS X. , VENDRAMIN G. G.
Published: December 2004

We used chloroplast polymerase chain reaction‐restriction‐fragment length polymorphism (PCR‐RFLP) and chloroplast microsatellites to assess the structure of genetic variation and postglacial history across the entire natural range of the common ash (Fraxinus excelsior L.), a broad‐leaved wind‐pollinated and wind‐dispersed European forest tree. A low level of polymorphism was observed, with only 12 haplotypes at four polymorphic microsatellites in 201 populations, and two PCR‐RFLP haplotypes in a subset of 62 populations. The clear geographical pattern displayed by the five most common haplotypes was in agreement with glacial refugia for ash being located in Iberia, Italy, the eastern Alps and the Balkan Peninsula, as had been suggested from fossil pollen data. A low chloroplast DNA mutation rate, a low effective population size in glacial refugia related to ash's life history traits, as well as features of postglacial expansion were put forward to explain the low level of polymorphism. Differentiation among populations was high (GST = 0.89), reflecting poor mixing among recolonizing lineages. Therefore, the responsible factor for the highly homogeneous genetic pattern previously identified at nuclear microsatellites throughout western and central Europe (Heuertz et al. 2004) must have been efficient postglacial pollen flow. Further comparison of variation patterns at both marker systems revealed that nuclear microsatellites identified complex differentiation patterns in south‐eastern Europe which remained undetected with chloroplast microsatellites. The results suggest that data from different markers should be combined in order to capture the most important genetic patterns in a species.