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Analysed Population (analysed + population)
Selected AbstractsGenetic differentiation and reproductive isolation of a naturally occurring floral homeotic mutant within a wild-type population of Capsella bursa-pastoris (Brassicaceae)MOLECULAR ECOLOGY, Issue 12 2009STEFFEN HAMEISTER Abstract Apart from the common floral architecture in Brassicaceae, variation in flower morphology occurs in several genera within the family and is considered to affect speciation processes. We analysed genetic differentiation and flowering time variation of two floral variants of Capsella bursa-pastoris, the Spe variant and the wild-type, which occur sympatrically in a vineyard in southwest Germany. The Spe variant is characterized by an additional whorl of stamens instead of petals and was formerly classified as an independent taxon ,Capsella apetala' Opiz. Amplified fragment length polymorphism and allozyme analysis revealed a substantial genetic differentiation of the two floral variants and a higher genetic variation within the wild-type subpopulation compared with the Spe subpopulation. The low genetic variation in the mutant provided evidence of a recent local origin or recent introduction. Flowering time analysis indicated that, within the analysed population, the Spe variant flowers significantly later than the wild-type (P < 0.001). We conclude that the evolution and persistence of Spe within a wild-type population is facilitated by high selfing rates and been enhanced by a shift in flowering phenology. Hence, our data provide substantial evidence that the Spe phenotype has established itself as an isolated entity within a wild-type population and may thus serve as a model for the analysis of the evolutionary significance of homeotic mutants in wild populations. [source] Natural course of sensitization to cow's milk and hen's egg in childhood atopic dermatitis: ETACTM Study GroupCLINICAL & EXPERIMENTAL ALLERGY, Issue 1 2002A. Wolkerstorfer Background Sensitization to food allergens has been implicated in the pathogenesis of atopic diseases, in particular atopic dermatitis (AD). The aim of the present paper is to investigate the natural course of sensitization to egg and to cow's milk and its relationship with the severity of AD. Methods The placebo intention-to-treat population of the ETACTM (Early Treatment of the Atopic Child) study consisted of 397 children with AD aged 12,24 months (mean±,SD: 17.2 ± 4.1 months) who were followed for 18 months. All children were examined for objective SCORing Atopic Dermatitis (SCORAD) and specific IgE amongst other, to egg and to cow's milk at inclusion and after 3, 12 and 18 months. Fifteen patients were excluded from this analysis due to major protocol violations thus leaving 382 patients in the analysed population. Results Sensitization to egg and to cow's milk was more common in atopic children with severe AD at all time-points. At inclusion, children sensitized to both egg and to cow's milk had the most severe AD (Kruskall-Wallis test P = 0.007). The degree of sensitization expressed in RAST classes was significantly related to the severity of AD. Furthermore, children sensitized to egg or to cow's milk at inclusion had a higher risk of persistence of AD (84% and 67%, respectively, vs. 57% in those not sensitized) and a higher objective SCORAD after 18 months follow-up. Conclusion We found an association between severity of AD and sensitization to egg or to cow's milk. Moreover, sensitization to egg, and to a lesser extent cow's milk, indicates a worse outcome of AD in terms of persistence and severity of the disease. [source] Eastern Beringian biogeography: historical and spatial genetic structure of singing voles in AlaskaJOURNAL OF BIOGEOGRAPHY, Issue 8 2010Marcelo Weksler Abstract Aim Pleistocene climatic cycles have left marked signatures in the spatial and historical genetic structure of high-latitude organisms. We examine the mitochondrial (cytochrome b) genetic structure of the singing vole, Microtus miurus (Rodentia: Cricetidae: Arvicolinae), a member of the Pleistocene Beringian fauna, and of the insular vole, Microtus abbreviatus, its putative sister species found only on the St Matthew Archipelago. We reconstruct the phylogenetic and phylogeographical structure of these taxa, characterize their geographical partitioning and date coalescent and cladogenetic events in these species. Finally, we compare the recovered results with the phylogenetic, coalescent and spatial genetic patterns of other eastern Beringian mammals and high-latitude arvicoline rodents. Location Continental Alaska (alpine and arctic tundra) and the St Matthew Archipelago (Bering Sea). Methods We generated and analysed cytochrome b sequences of 97 singing and insular voles (M. miurus and M. abbreviatus) from Alaska. Deep evolutionary structure was inferred by phylogenetic analysis using parsimony, maximum likelihood and Bayesian approaches; the geographical structure of genetic diversity was assessed using analysis of molecular variance and network analysis; ages of cladogenetic and coalescent events were estimated using a relaxed molecular clock model with Bayesian approximation. Results Regional nucleotide diversity in singing voles is higher than in other high-latitude arvicoline species, but intra-population diversity is within the observed range of values for arvicolines. Microtus abbreviatus specimens are phylogenetically nested within M. miurus. Molecular divergence date estimates indicate that current genetic diversity was formed in the last glacial (Wisconsinan) and previous interglacial (Sangamonian) periods, with the exception of a Middle Pleistocene split found between samples collected in the Wrangell Mountains region and all other singing vole samples. Main conclusions High levels of phylogenetic and spatial structure are observed among analysed populations. This pattern is consistent with that expected for a taxon with a long history in Beringia. The spatial genetic structure of continental singing voles differs in its northern and southern ranges, possibly reflecting differences in habitat distribution between arctic and alpine tundra. Our phylogenetic results support the taxonomic inclusion of M. miurus in its senior synonym, M. abbreviatus. [source] Genetic variation and relationships among Turkish water buffalo populationsANIMAL GENETICS, Issue 1 2010M. Gargani Summary The genetic variation and relationships among six Turkish water buffalo populations, typical of different regions, were assessed using a set of 26 heterologous (bovine) microsatellite markers. Between seven and 17 different alleles were identified per microsatellite in a total of 254 alleles. The average number of alleles across all loci in all the analysed populations was found to be 12.57. The expected mean heterozygosity (He) per population ranged between 0.5 and 0.58. Significant departures from Hardy,Weinberg equilibrium were observed for 44 locus,population combinations. Population differentiation was analysed by estimation of the Fst index (values ranging from 0.053 to 0.123) among populations. A principal component analysis of variation revealed the Merzifon population to show the highest differentiation compared with the others. In addition, some individuals of the Danamandira population appeared clearly separated, while the Afyon, Coskun, Pazar and Thural populations represented a single cluster. The assignment of individuals to their source populations, performed using the Bayesian clustering approach implemented in the structure 2.2 software, supports a high differentiation of Merzifon and Danamandira populations. The results of this study are useful for the development of conservation strategies for the Turkish buffalo. [source] | ||||||||||