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French Population (french + population)
Selected AbstractsPrediction of transition from cognitive impairment to senile dementia: a prospective, longitudinal studyACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2003S. Artero Objective: The purpose of this investigation was to replicate the statistical approach used in a previous investigation (Toronto study) within a French population to determine the best predictive model for Alzheimer's disease (AD). Method: Data from neuropsychological tests from two prospective studies were entered into a regression model. Results: Replication of the statistical approach in the Montpellier sample produced a three-test model with a specificity of 99% and sensitivity of 73%. This model consisted of a delayed auditory verbal recall test, a construction test, a category fluency test and provides probability estimates for the transition to dementia in individual cases. Conclusion: The models derived from these two longitudinal studies provide an empirical basis for the selection of tests for the definition of mild cognitive impairment of the Alzheimer type (MCI-A). The small set of tests derived are suitable for use in general practice. [source] Determination of ABCB1 polymorphisms and haplotypes frequencies in a French populationFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 4 2007Elise Jeannesson Abstract The ATP-binding cassette (ABC) transporter ABCB1, or P-glycoprotein, is a transmembrane efflux pump well known for its implication in drug transport and chemoresistance. ABCB1 substrates include either drugs, such as antiretrovirals and immunomodulators, or physiological molecules like phospholipids. Pharmacogenetic analysis of ABCB1 polymorphisms, in addition to other xenobiotic metabolizing enzymes, might help to personalize and optimize drug therapy. Indeed, some polymorphisms of ABCB1 have been implicated in susceptibility to diseases, changes in drug pharmacokinetics, and in variation of the biological response to drug treatment. In addition, variant and haplotype distributions differ depending on ethnicity. Thus, some ethnies may be at higher risk for adverse events, inefficacy of treatment or prevalence of pathologies. This study aimed to determine frequencies of ABCB1 polymorphisms and haplotypes in a sample of French healthy individuals. DNA was isolated from blood-EDTA. Polymerase chain reaction-restriction fragment length polymorphism and TaqMan single nucleotide polymorphism genotyping assays were used to genotype 227 individuals for T-129C, G-1A, A61G, G1199A, C1236T, T-76A, G2677T/A and C3435T polymorphisms. The observed frequencies of the variant allele for these eight polymorphisms are 0.04, 0.08, 0.09, 0.06, 0.42, 0.46, 0.45 and 0.46 respectively. These polymorphisms are in linkage disequilibrium and haplotype frequencies were determined, the most frequent haplotype being the one with variants at position 1236, 2677 and 3435 and wild-type alleles at the other positions. Finally, the frequencies of these eight ABCB1 polymorphisms in our French individuals supposed to be healthy population are quite similar to those described in other Caucasian populations except for the C3435T polymorphism. [source] Metabolic syndrome, insulin resistance, and periodontitis: a cross-sectional study in a middle-aged French populationJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 7 2010Catherine Benguigui Benguigui C, Bongard V, Ruidavets J-B, Chamontin B, Sixou M, Ferrières J, Amar J. Metabolic syndrome, insulin resistance and periodontitis: a cross-sectional study in a middle-aged French population. J Clin Periodontol 2010; 37: 601,608. doi: 10.1111/j.1600-051X.2010.01571.x. Abstract Aim: Metabolic syndrome consists of a cluster of clinical and biological abnormalities, influenced by insulin resistance and promoting cardiovascular diseases. We examined the relationships between metabolic syndrome, its various components, insulin resistance, and periodontitis. Materials and Methods: The study included 276 subjects (35,74 years) recruited within a cross-sectional survey on cardiovascular risk factors. Twenty-one were excluded because of infectious risk or total tooth loss. Clinical attachment loss (CAL), probing pocket depth (PD), gingival and plaque indexes were recorded. Periodontitis was classified into moderate and severe forms. Results: The mean age was 58, 41% of the subjects had moderate and 39% had severe periodontitis. In univariate comparisons, periodontitis was associated with metabolic syndrome (p=0.050), most of its components, and HOMA index (homoeostasis model assessment of insulin resistance). After adjustment for confounders, only HOMA index remained associated with severe periodontitis (odds ratio [OR]=3.97 [95% confidence interval: 1.22,12.9], OR=3.78 [1.14,12.5] for third and fourth versus the first quartile of the HOMA index, respectively). The HOMA index was also associated with the number of periodontal sites with CAL4 mm, CAL5 mm, or PD4 mm (greater number for higher HOMA-index values). This relationship disappeared in never-smokers. Conclusions: Our data support the relationships between metabolic disturbances and periodontitis, with a central role of insulin resistance. [source] Genetic Repeat Polymorphism in the Regulating Region of CYP2E1: Frequency and Relationship With Enzymatic Activity in AlcoholicsALCOHOLISM, Issue 6 2001E. Plee-Gautier Background: Differences in the regulatory region of the CYP2E1 gene could be responsible for the interindividual variation in the cytochrome P-450 2E1 (CYP2E1) involved in ethanol oxidation. Recently, a polymorphic repeat sequence in the human gene was described between ,2178 and ,1945 base pairs. Its frequency seemed to vary among different ethnic populations, and it was suspected to be related to an increased inducibility to further ethanol intake. In the study reported here, the frequency of this polymorphism was investigated in a white French population. Its relationship with the previously described Pst I/Rsa I or Dra I CYP2E1 polymorphisms, alcoholism, alcoholic liver disease, and inducibility of CYP2E1 by ethanol was examined. Methods: The polymorphic region was characterized by polymerase chain reaction in 103 controls, 148 alcoholic subjects without liver diseases, and 98 others with liver cirrhosis. By using in vivo chlorzoxazone (CHZ) metabolism, CYP2E1 phenotype was assessed in 36 non,ethanol-induced subjects (17 controls and 19 withdrawn alcoholics) and in 14 ethanol-induced subjects (10 controls after ingestion of 0.8 g/kg ethanol and four alcoholics with 100 g of daily intake). This phenotype was expressed as the 6-hydroxy CHZ/CHZ ratio. Results: The rare allele frequency was found to be 1.58% in whites (n= 349). Neither significant association with alcoholism or alcoholic liver diseases, nor relationship with the Pst I/Rsa I polymorphism, was observed. But the Dra I polymorphism was more frequent among the heterozygous subjects when compared with wild-type homozygous ones (p < 0.05). The CYP2E1 phenotype was similar in wild-type homozygotes and in heterozygotes at the constitutive level, as well as after induction with ethanol. Conclusions: Our data suggest that CYP2E1 repeat polymorphism does not seem to constitute a major factor for interindividual differences in CYP2E1 expression and susceptibility to alcohol-related disorders in whites. [source] Type III hereditary angio-oedema: clinical and biological features in a French cohortALLERGY, Issue 10 2010V. Vitrat-Hincky To cite this article: Vitrat-Hincky V, Gompel A, Dumestre-Perard C, Boccon-Gibod I, Drouet C, Cesbron JY, Lunardi J, Massot C, Bouillet L. Type III hereditary angio-oedema: clinical and biological features in a French cohort. Allergy 2010; 65: 1331,1336. Abstract Background:, Hereditary angio-oedema (HAE) has been associated with C1inhibitor deficiency. The first cases of type III HAE were described in patients with normal C1Inh antigenic protein level and function and normal C4 levels in 2000. This finding has been reported mostly in women with a family history and may be influenced by exogenous oestrogen exposure. Objectives:, The purpose of this article is to describe the clinical, biological and genetic characteristics of a French population suffering from type III HAE. Patients and Methods:, We conducted a retrospective analysis of angio-oedema (AE) cases seen in the National Reference Centre of AE between 2000 and 2009. Results:, We found 26 patients (from 15 unrelated families) with type III HAE. All but four were women and presented with typical AE attacks, exacerbated by pregnancy or oral contraceptives containing oestrogens (OC). We also found that 54.5% of women were worsened with oestrogen and 23% were oestrogen dependent. All patients improved on long-term prophylactic tranexamic acid treatment; some acute attacks improved with C1Inh concentrate infusion. All of the patients had normal C1Inh and C4 levels. C1Inh function was also normal, except in women receiving OC or during a pregnancy: transient, moderately low levels (32,74% of the normal range) were found in 18 patients tested (67%). No SERPING1 gene mutation was found. Six patients from three unrelated families were heterozygous for an F12 gene variant. Conclusion:, Diagnosis of type III HAE should be based on clinical (typical attacks, often hormonally influenced), laboratory (normal C1Inh antigenic protein) and genetic (F12 gene mutation) evidence. [source] Eleven polymorphic microsatellite markers for Oedaleus decorus (Orthoptera, Acrididae), an endangered grasshopper in Central EuropeMOLECULAR ECOLOGY RESOURCES, Issue 6 2008K. BERTHIER Abstract We isolated and characterized 11 microsatellite loci in the grasshopper Oedaleus decorus (Orthoptera: Acrididae), an endangered species in Central Europe. Polymorphism was studied from two populations, one out of two populations known from Switzerland (n = 20 individuals) and one site from south of France (n = 20). The number of alleles and the expected heterozygosity ranged from five to 12 and from 0.559 to 0.898, respectively, in the Swiss population, and from 14 to 23 and from 0.895 to 0.974, respectively, in the French population. These microsatellite markers are suitable for further conservation genetic studies of O. decorus. [source] Drug related falls: a study in the French Pharmacovigilance database,,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 1 2005Emmanuelle Souchet Abstract Objective To investigate the risk of falls associated with drugs among the French population using data reported to the French spontaneous reporting system and recorded in the French Pharmacovigilance database. Methods All cases including a fall were searched in the French Pharmacovigilance database between 1995 and 1999. Drugs involved and characteristics of patients were investigated. In a second step, we estimated the risk associated with psychotropic and cardiovascular drugs in a case/non case comparison, where cases were reports including a fall and non cases all other reports. This risk was estimated by calculation of crude and age and gender adjusted reporting odds ratios (ROR). Results During this period, 328 reports including a fall were reported (0.4% of the database). Patients were female in 70%. Mean age was 76,±,18 years. Comparisons between cases and non cases showed that cases were more likely to be women (OR: 1.9; 95% confidence interval (CI) [1.5,2.4]) and older. After adjustment on age and gender, falls remained significantly associated with exposure to benzodiazepines (4.7,[3.7,5.9]), imipraminic antidepressants (3.6 [2.5,5.1]), serotonin reuptake inhibitor (SRI) antidepressants (2.2 [1.5,3.1]) or nitrates (1.9 [1.2,2.8]). Conclusion This study confirms that taking psychotropic drugs strongly increases the risk of falls. The role of cardiovascular drugs (except nitrates) remains not significant when confounding factors are taken into account. According to the very high prevalence of psychotropic drug use in the French elderly, further study are needed to investigate the relative effect of some drugs on falls, like for example SRIs or short acting benzodiazepines. Copyright © 2004 John Wiley & Sons, Ltd. [source] Prevalence of common mental disorders and their work consequences in France, according to occupational categoryAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2009Christine Cohidon MD Abstract Background The aims of the study are to estimate the prevalence of the common mental disorders according to occupational category and to describe the consequences of these disorders on their work, in the French population. Methods It took place in France from 1999 to 2003. The sample consisted of about 36,000 people aged 18 years and older. Data were collected face-to-face using the Mini International Neuropsychiatric Interview (MINI). Results Anxiety disorders were most common (17% in men and 26% in women), while prevalence estimates for mood disorders were 10% in men and 14% in women. Prevalence of troubles were consistently higher among those in the lowest occupational categories. Among those reporting mental disorders, about 50% said that their work was affected. The repercussions on job varied by occupational category and differently for men and women. Conclusion This study shows the social and occupational inequalities in the prevalence of mental disorders and their important work consequences in the French working population. Am. J. Ind. Med. 52:141,152, 2009. © 2008 Wiley-Liss, Inc. [source] A Genetic Study of the Ghrelin and Growth Hormone Secretagogue Receptor (GHSR) Genes and StatureANNALS OF HUMAN GENETICS, Issue 1 2009M. Gueorguiev Summary Growth and nutrition are interrelated and influenced by multiple genetic and environmental factors. We studied whether common variants in ghrelin and ghrelin receptor (GHSR) genes could play a role in stature variation in the general population and in families ascertained for obesity. Selected tagging SNPs in the ghrelin and GHSR genes were genotyped in 263 Caucasian families recruited for childhood obesity (1,275 subjects), and in 287 families from a general population (1,072 subjects). We performed familial testing for associations in the entire population and in a sub-set of the samples selected for a case-control study. In the case-control study for height (cases were selected from the obese cohort with mean ZH = 3.17 ± 0.15 confidence interval (CI) versus controls with mean ZH 0.14 ± 0.09), we found an association with a 2 base-pair intronic deletion in the GHSR gene (rs10618418) (p = 0.006, odds ratio (OR) 1.86, 95% CI [1.26;2.74] under additive model), although when adjusting for BMI, the association disappeared (p = 0.06). Individuals carrying no deletion or who were heterozygous were significantly more frequent among the tall obese population (52% vs. 36% in controls, p = 0.007, OR 1.97, 95%CI [1.22;3.18]). However, the association was not maintained after correcting for multiple testing. Familial association testing of the ghrelin and GHSR genes and their interaction testing failed to show that any combination of SNPs had any significant effect. Thus, our results suggest that common variants of the ghrelin and GHSR genes are not major contributors to height variation in a French population. [source] THE UNPAID LEADERS OF FRENCH VOLUNTARY ASSOCIATIONSANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 1 2010Lionel Prouteau ABSTRACT,:,This paper focuses on the voluntary workers who take on responsibilities in French voluntary associations. First, drawing on a national association survey, we contrast the characteristics of leadership volunteers, especially chairpersons, with those of the French population as a whole. We show that leaders are very different from the overall population even if these differences seem to diminish for organizations created more recently. Second, from a national household survey, we compare board members with other members of associations. Among other results, we find that the former are more rooted in their local environment and they participate more frequently in several associations. They are driven by more activist motives than are the other members. They give more time to their associations and they use more skills in their voluntary tasks than do the other volunteers. [source] Organization, Management and Delegation in the French Water IndustryANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 4 2001Jihad C. Elnaboulsi The water industry is largely a natural monopoly. Water distribution and sewerage services are characterized by networks and its natural monopoly derives from the established local networks of drinking water and sewers: they are capital intensive with sunk costs and increasing returns to scale. In France, local communities have a local requirement of providing public services under optimum conditions in terms of techniques and cost-effectiveness, and subject to respect different kind of standards in terms of water quality and level of services. They are responsible for producing and distributing drinking water, and collecting and treating wastewater. Furthermore, the French water utilities are required to be financially self-sufficient. Rate-setting varies across regions and local territories due to a variety of organizational features of services and availability of water resources. The management of these local public services can be public or private: local governments have the right, by the constitution, to delegate water service management to private companies which operate under the oversight of local municipal authorities. Today, nearly 80 per cent of the French population receive private distributed water. Different reasons are responsible for the poor performance and low productivity of most French public water utilities: technical and operational, commercial and financial, human and institutional, and environmental. Thus, many water public utilities have looked for alternative ways to provide water and sanitation services more efficiently, to improve both operational and investment efficiency, and to attract private finance. The purpose of this paper is to present the French organizational system of providing drinking water services, and collecting and treating wastewater services: legal aspects, contracts of delegation, and competition. [source] Association of a functional polymorphism in the IRF5 region with systemic sclerosis in a Japanese populationARTHRITIS & RHEUMATISM, Issue 6 2009Ikue Ito Objective Interferon regulatory factor 5, an established susceptibility factor for systemic lupus erythematosus (SLE), plays a role in type I interferon and proinflammatory cytokine induction. A recent study showed association of a functional single-nucleotide polymorphism (SNP) in intron 1 of IRF5, rs2004640, with systemic sclerosis (SSc) in a European French population. We undertook the present study to determine whether IRF5 polymorphisms are also associated with a predisposition to SSc in Japanese. Methods A case,control association study was performed for rs2004640 as well as for rs10954213 and rs2280714, all of which were previously reported to be associated with SLE, in 281 SSc patients and 477 healthy controls. Patients with SSc complicated by SLE or Sjögren's syndrome were excluded. Association of the rs2280714 genotype with messenger RNA (mRNA) levels of IRF5 and adjacently located transportin 3 (TNPO3) was examined using the GENEVAR database. Results All 3 SNPs were significantly associated with SSc, with the rs2280714 A allele having the strongest association (allele frequency P = 0.0012, odds ratio 1.42 [95% confidence interval 1.15,1.75]). Association was preferentially observed in subsets of patients with diffuse cutaneous SSc (dcSSc) and anti,topoisomerase I antibody positivity. Conditional analysis revealed that rs2280714 could account for most of the association of these SNPs, while an additional contribution of rs2004640 was also suggested for dcSSc. The genotype of rs2280714 was strongly associated with IRF5 mRNA expression, while only marginal association was detected with TNPO3 mRNA expression. Conclusion Association of IRF5 with SSc was replicated in a Japanese population. Whether the causal SNP is different among populations requires further investigation. [source] Significant paternal contribution to the risk of small for gestational ageBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 2 2005Delphine Jaquet Objective The aim of this study is to investigate both maternal and paternal contributions in the familial aggregation of small for gestational age. Design Nested case,control study. Setting Metropolitan area of Haguenau, France. Population Data were drawn from a French population-based maternity registry. After selection, 256 cases born either small for gestational age or average for gestational age were included. Methods Controlling for known pregnancy-related risk factors, logistic regression models were used to determine the risk of the child being small for gestational age, given that the mother, father or both were small for gestational age, and to examine interactions between maternal small for gestational age and pregnancy risk factors. Main outcome measures Specifically, we investigate to what extent having either or both parents born small for gestational age increases the risk of small for gestational age in their offspring, after controlling for the established risk factors of small for gestational age and maternal and paternal characteristics. We also explore the extent to which the intergenerational predictors of small for gestational age may modify the effect of current pregnancy-related risk factors. Results The risk of a small for gestational age offspring was 4.7 times greater for mothers and 3.5 times greater for fathers who were small for gestational age, compared with average for gestational age counterparts. Furthermore, the risk of a small for gestational age offspring was 16.3 times greater when both parents were small for gestational age. No significant interactions between maternal small for gestational age and maternal smoking, hypertension or parity were observed. Conclusion These results indicate that small for gestational age in both mother and father significantly influences the risk of their offspring being small for gestational age. While previous research has indicated that the birth outcome of the mother is an important determinant of the birth outcome of her offspring, these data indicate that the birth outcome of the father plays an equally critical role in determining fetal growth, strongly suggesting a genetic component in the familial aggregation of small for gestational age. [source] HIV-1 genetic diversity in Western Brittany, FranceFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2002Sophie Vallet Abstract We describe human immunodeficiency virus type 1 (HIV-1) diversity in Western Brittany, France, and trace the dissemination of HIV-1 non-B subtype infection. The strategy for HIV-1 subtyping used involved subtype specific enzyme immunoassays, heteroduplex mobility assays and phylogenetic analysis of the sequences of env encoding the V3 loop region. Samples were obtained from 567 patients: 465 (82%) were of subtype B and 66 (11.6%) were not (20 were subtype A, 11 subtype C, four subtype D, seven subtype F, five subtype G and 19 others with circulating recombinant forms: 4CRF01_AE, 11CRF02_AG, 1H, 3CRF11_cpx). These findings are consistent with other studies of French populations. There is an epidemiological correlation between subtype B and homosexual or heterosexual contamination in France and between non-B subtype and heterosexual contamination in Africa. [source] Frequency of cytochrome P450 2C9 allelic variants in the Chinese and French populationsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2003Jue Quin Yang Abstract Cytochrome P450 2C9 (CYP2C9) is a polymorphic enzyme responsible for the metabolism of different drugs with low therapeutic index such as oral anticoagulants. CYP2C9*2 and CYP2C9*3 are two single nucleotide polymorphic allelic variants. The frequency of these alleles in different ethnic populations is extremely variable. In this study, we compared the frequencies of CYP2C9 allelic variants among 394 Chinese living in Shanghai to 151 French Caucasians living in Paris. The allelic frequencies of CYP2C9 variants of the Chinese and the French subjects were 0.963, 0.001, 0.036 and 0.77, 0.15, 0.08 for CYP2C9*1, CYP2C9*2, CYP2C9*3, respectively. Chinese CYP2C9*3 allelic frequency was twice as lower as the French subjects, but three times higher than Korean (0.036 vs. 0.011). The CYP2C9*2 allele could be detected in only one Chinese subject, whereas it represented the major allelic variant in French Caucasians. The low frequency of the CYP2C9*2 and CYP2C9*3 allelic variants in Chinese subjects does not justify their detection in clinical practice, unlike French Caucasians. [source] Microsatellite variation in autochthonous and introduced populations of the Alpine marmot (Marmota marmota) along a European west,east transectJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 1 2004L. Kruckenhauser Abstract Microsatellite variation was studied in 11 populations of the Alpine marmot along a west,east transect through the present distribution range. The samples represent five autochthonous and six introduced populations. Eleven loci were analysed in nine populations and six loci in the two populations from France. In the populations from the Western Alps, there is no indication for reduced variability as has been assumed in previous studies. However, a decrease of variation in the autochthonous populations was observed from the west to the east. The introduced populations showed a heterogeneous pattern reflecting the geographic origin of the released individuals. The population from the Spanish Pyrenees harbours a high level of variation and is genetically closest to the French populations. In Austria, three of the introduced populations have low variation and are closely related to the autochthonous populations from the western part of Austria. In contrast, two introduced populations from the central part of Austria are highly variable and resemble the populations from France. At least for one of these populations an early introduction of founder individuals from the Western Alps has been documented. Zusammenfassung Die Mikrosatellitenvariation wurde in 11 Populationen des Alpenmurmeltieres entlang eines west-ost Gradienten durch das gegenwärtige Verbreitungsgebiet untersucht. Die Stichproben repräsentieren fünf autochthone und sechs eingebürgerte Populationen. Elf Loci wurden in neun Populationen analysiert und sechs Loci in den beiden Populationen aus Frankreich. In den Populationen aus den Westalpen ergab sich im Gegensatz zu früheren Untersuchungen kein Hinweis auf eine Reduktion der Variabilität. Innerhalb der autochthonen Populationen ist jedoch eine Abnahme der Variation von Westen nach Osten festzustellen. Die eingebürgerten Populationen zeigten ein uneinheitliches Muster, welches den geografischen Ursprung der ausgesetzten Individuen widerspiegelt. Die Population aus den spanischen Pyrenäen besitzt eine hohe Variation und ist genetisch den französischen Populationen am ähnlichsten. In Österreich zeigen drei der eingebürgerten Populationen niedrige Variation und sind den autochthonen Populationen aus Westösterreich am nächsten verwandt. Hingegen sind die beiden eingebürgerten Populationen aus Zentralösterreich hoch variabel und den Populationen aus Frankreich ähnlich. Zumindest für eine dieser beiden Populationen ist eine frühe Einbürgerung von Gründerindividuen aus den Westalpen dokumentiert. [source] The invasive red swamp crayfish as a predictor of Eurasian bittern density in the Camargue, FranceJOURNAL OF ZOOLOGY, Issue 1 2007B. Poulin Abstract Few data exist on the relationships between food levels and breeding density of the Eurasian bittern Botaurus stellaris, a vulnerable species of high-priority concern in Europe. Concurrent data were obtained on male bittern density and relative food abundance over a 3-year period in two wetlands totalling 2500 ha of Mediterranean reed marsh enclosing 25% of the French bittern population. Food abundance was estimated by sampling up to 25 hydrological units using a beach seine in early June of 2002, 2003 and 2004. The density of booming males in each hydrological unit was obtained by point counts and acoustic triangulation in May of the same years. The impact of food abundance on male bittern density was assessed by general regression models using a forward stepwise procedure with mosquitofish Gambusia affinis, carp Cyprinus carpio, other fish species, amphibians, red swamp crayfish Procambarus clarkii and other invertebrates as prey groups. Of these, only to crayfish abundance was bittern density related, contributing to 45% of the variance observed. When the impact of water level was taken into account, the relative abundance of crayfish explained 56% of the inter-annual differences in bittern density. Because crayfish are rich in calcium and well adapted to fluctuating hydroperiods alternating with drought intervals, they provide a good food source for the bitterns throughout the breeding season at the study sites. The loss of diversity and degradation reported from macrophyte-dominated marshes following crayfish invasion does not seem to apply to reed-dominated wetlands. It is further suggested that the recent increase in bittern numbers in the Camargue, while other French populations were decreasing, could in part be related to red swamp crayfish abundance. [source] Genetic structure and gene flow in French populations of two Ostrinia taxa: host races or sibling species?MOLECULAR ECOLOGY, Issue 20 2007T. MALAUSA Abstract Most models of ecological speciation concern phytophagous insects in which speciation is thought to be driven by host shifts and subsequent adaptations of populations. Despite the ever-increasing number of studies, the current evolutionary status of most models remains incompletely resolved, as estimates of gene flow between taxa remain extremely rare. We studied the population genetics of two taxa of the Ostrinia genus , one feeding mainly on maize and the other on mugwort and hop , occurring in sympatry throughout France. The actual level of divergence of these taxa was unknown because the genetic structure of populations had been investigated over a limited geographical area and the magnitude of gene flow between populations had not been estimated. We used 11 microsatellite markers to investigate the genetic structure of populations throughout France and the extent of gene flow between the two Ostrinia taxa at several sites at which they are sympatric. We observed clear genetic differentiation between most populations collected on the typical respective hosts of each taxon. However, populations displaying intermediate allelic frequencies were found on hop plants in southern France. Individual assignments revealed that this result could be accounted for by the presence of both taxa on the same host. Gene flow, estimated by determining the proportion of hybrids detected, was low: probably < 1% per generation, regardless of site. This indicates that the two Ostrinia taxa have reached a high level of genetic divergence and should be considered sibling species rather than host races. [source] | |||||||||||||