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Populations Only (population + only)
Selected AbstractsThe social parasite wasp Polistes atrimandibularis does not form host racesJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2005D. FANELLI Abstract Parasites that exploit the parental behaviour of several host species may be selected to form distinct host-specific genetic lineages. This process is well documented in bird brood parasites, but not in insect social parasites. Polistes atrimandibularis is the only paper-wasp social parasite known to exploit four host species. It does not form genetically distinct host races according to analyses based on microsatellite loci. Also, there were no size-matching between parasites and host species. Instead, P. atrimandibularis queens seemed to be successful as parasites in this population only when they originated from nests of P. dominulus, the largest species. The other host species are a sink for P. atrimandibularis since adult females emerging from those nests appear too small to usurp colonies themselves. Traits that may help P. atrimandibularis infiltrate multiple species may include its nonaggressive usurpation tactics and its ability to acquire host cuticular hydrocarbon recognition labels. [source] Screening for Prostate, Breast and Colorectal Cancer in Renal Transplant RecipientsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2003Bryce A. Kiberd American Society of Transplantation guidelines recommend screening renal transplant recipients for breast, colorectal and prostate cancer. However there is a lack of evidence to support this practice. Computer simulation modeling was used to estimate the years of life lost as a result of these cancers in 50-year-old renal transplant recipients and subjects in the general population. Renal transplant recipients lost fewer years of life to cancer than people in the general population largely because of reduced life expectancy. In nondiabetic transplant recipients, loss of life as a result of these cancers was comparable with that in the general population only under assumptions of increased cancer incidence and cancer-specific mortality risks. Even with two-fold higher cancer incidence and disease-specific mortality risks, diabetic transplant recipients lost considerably fewer life years to cancer than those in the general population. Recommended cancer screening for the general population may not yield the expected benefits in the average renal transplant recipient but the benefits will be considerably higher than for patients on dialysis. Transplanted patients at above-average cancer risk in good health may achieve the benefits of screening that are seen in the general population. [source] Construct validity and generalizability of the Carver,White behavioural inhibition system/behavioural activation system scalesEUROPEAN JOURNAL OF PERSONALITY, Issue 5 2001Luigi Leone The factorial structure and invariance of the BIS/BAS scales of Carver and White were assessed across three samples from the USA, UK, and Italy. Previous validation studies of the BIS/BAS scales relied on individual samples drawn from English-speaking populations only and failed to formally assess generalizability. The current study shows that the four-factor structure proposed by Carver and White,i.e. one BIS and three BAS facets,achieved satisfactory psychometric properties in all three samples and that measurement invariance was obtained across countries. Latent mean differences due to gender and country were also investigated. Theoretical issues concerning the validity of the BIS/BAS scales are addressed. Copyright © 2001 John Wiley & Sons, Ltd. [source] Linked vs. unlinked markers: multilocus microsatellite haplotype-sharing as a tool to estimate gene flow and introgressionMOLECULAR ECOLOGY, Issue 2 2007WIM J. M. KOOPMAN Abstract We have explored the use of multilocus microsatellite haplotypes to study introgression from cultivated (Malus domestica) into wild apple (Malus sylvestris), and to study gene flow among remnant populations of M. sylvestris. A haplotype consisted of alleles at microsatellite loci along one chromosome. As destruction of haplotypes through recombination occurs much faster than loss of alleles due to genetic drift, the lifespan of a multilocus haplotype is much shorter than that of the underlying alleles. When different populations share the same haplotype, this may indicate recent gene flow between populations. Similarly, haplotypes shared between two species would be a strong signal for introgression. As the expected lifespan of a haplotype depends on the strength of the linkage, the length [in centiMorgans (cM)] of the haplotype shared contains information on the number of generations passed. This application of shared haplotypes is distinct from using haplotype-sharing to detect association between markers and a certain trait. We inferred haplotypes for four to eight microsatellite loci on Linkage Group 10 of apple from genotype data using the program phase, and then identified those haplotypes shared between populations and species. Compared with a Bayesian analysis of unlinked microsatellite loci using the program structure, haplotype-sharing detected a partially different set of putative hybrids. Cultivated haplotypes present in M. sylvestris were short (< 1.5 cM), indicating that introgression had taken place many generations ago, except for two Belgian plants that contained a haplotype of 47.1 cM, indicating recent introgression. In the estimation of gene flow, FST based on unlinked loci indicated small (0.032,0.058) but statistically significant differentiation between some populations only. However, various M. sylvestris haplotypes were shared in nearly all pairwise comparisons of populations, and their length indicated recent gene flow. Hence, all Dutch populations should be considered as one conservation unit. The added value of using sharing of multilocus microsatellite haplotypes as a source of population genetic information is discussed. [source] Importance of secondary inoculum of Plasmopara viticola to epidemics of grapevine downy mildewPLANT PATHOLOGY, Issue 4 2005D. Gobbin To quantify the magnitude and the spatial spread of grapevine downy mildew secondary sporangia, 4685 Plasmopara viticola single lesion samples were collected from 18 plots spread across central Europe. Disease symptoms were collected on two to 22 sampling dates per plot between 2000 and 2002. Four multiallelic microsatellite markers were used for genotypic identification of pathogen samples. Genetic analysis showed more than 2300 site-specific P. viticola genotypes, indicating that populations are genetically rich demographic units. Approximately 70% of the genotypes were sampled once and 14% were sampled twice throughout the various epidemics. In the 18 populations only seven genotypes (0.3%) were identified more than 50 times. Three genotypes particularly successful in causing disease through secondary cycles showed mainly a clustered distribution. The distance of sporangial migration per secondary cycle was less than 20 m and their plot colonization rate was calculated at around 1,2 m2 day,1. Downy mildew epidemics of grapevine are therefore the result of the interaction of a multitude of genotypes, each causing limited (or a few) lesions, and of a dominant genotype able to spread stepwise at plot-scale. These findings contrast with current theories about grapevine downy mildew epidemiology, which postulate that there is massive vineyard colonization by one genotype and long-distance migration of sporangia. [source] Can fluctuating asymmetry be used to detect inbreeding and loss of genetic diversity in endangered populations?ANIMAL CONSERVATION, Issue 2 2000Dean M. Gilligan Fluctuating asymmetry (FA), a measure of developmental stability, has been proposed as a simple technique for identifying populations suffering from inbreeding and a loss of genetic diversity. However, there is controversy regarding the relationship between FA and both allozyme heterozygosity and pedigree inbreeding coefficients (F). FA of sternopleural bristle number in Drosophila melanogaster was measured in populations maintained at effective sizes of 25 (8 replicates), 50 (6), 100 (4), 250 (3) and 500 (2) for 50 generations (inbreeding coefficients of 0.05,0.71). FA was calculated from the same data set using three different indices (FA1, FA5 and FA6). There was no significant relationship of FA with pedigree inbreeding coefficients for any of the three indices. The relationship between FA and allozyme heterozygosity was non-significant for indices FA5 and FA6 (the more powerful indices) and only significant for FA1. A second comparison of highly inbred (F , 1) populations with their outbred base population showed significantly greater FA in the inbred populations only when analysed with FA6. Analysis of the same data using FA1 and FA5 showed non-significant relationships in the opposite direction. If a relationship between FA and genetic diversity does exist, it is weak and inconsistent. Consequently, our results do not support the use of FA as a monitoring tool to detect inbreeding or loss of genetic diversity. [source] Large-scale analysis of association between GDF5 and FRZB variants and osteoarthritis of the hip, knee, and handARTHRITIS & RHEUMATISM, Issue 6 2009Evangelos Evangelou Objective GDF5 and FRZB have been proposed as genetic loci conferring susceptibility to osteoarthritis (OA); however, the results of several studies investigating the association of OA with the rs143383 polymorphism of the GDF5 gene or the rs7775 and rs288326 polymorphisms of the FRZB gene have been conflicting or inconclusive. To examine these associations, we performed a large-scale meta-analysis of individual-level data. Methods Fourteen teams contributed data on polymorphisms and knee, hip, and hand OA. For rs143383, the total number of cases and controls, respectively, was 5,789 and 7,850 for hip OA, 5,085 and 8,135 for knee OA, and 4,040 and 4,792 for hand OA. For rs7775, the respective sample sizes were 4,352 and 10,843 for hip OA, 3,545 and 6,085 for knee OA, and 4,010 and 5,151 for hand OA, and for rs288326, they were 4,346 and 8,034 for hip OA, 3,595 and 6,106 for knee OA, and 3,982 and 5,152 for hand OA. For each individual study, sex-specific odds ratios (ORs) were calculated for each OA phenotype that had been investigated. The ORs for each phenotype were synthesized using both fixed-effects and random-effects models for allele-based effects, and also for haplotype effects for FRZB. Results A significant random-effects summary OR for knee OA was demonstrated for rs143383 (1.15 [95% confidence interval 1.09,1.22]) (P = 9.4 × 10,7), with no significant between-study heterogeneity. Estimates of effect sizes for hip and hand OA were similar, but a large between-study heterogeneity was observed, and statistical significance was borderline (for OA of the hip [P = 0.016]) or absent (for OA of the hand [P = 0.19]). Analyses for FRZB polymorphisms and haplotypes did not reveal any statistically significant signals, except for a borderline association of rs288326 with hip OA (P = 0.019). Conclusion Evidence of an association between the GDF5 rs143383 polymorphism and OA is substantially strong, but the genetic effects are consistent across different populations only for knee OA. Findings of this collaborative analysis do not support the notion that FRZB rs7775 or rs288326 has any sizable genetic effect on OA phenotypes. [source] | |||||||||||||