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High Polymorphism (high + polymorphism)
Selected AbstractsSpatial pattern of MHC class II variation in the great snipe (Gallinago media)MOLECULAR ECOLOGY, Issue 7 2007ROBERT EKBLOM Abstract The genes of the major histocompatibility complex (MHC) code for proteins involved in antigen recognition and triggering of the adaptive immune response, and are therefore likely to be under selection from parasites. These selection regimes may vary in space and time. Here we report a strong geographical structure in MHC class II B genes of a migrating bird, the great snipe (Gallinago media). Genetic differentiation in the MHC between two ecologically distinct distributional regions (Scandinavian mountain populations vs. East European lowland populations) was still present after statistically controlling for the effect of selectively neutral variation (microsatellites) using partial Mantel tests. This suggests a role for selection in generating this spatial structure and that it represents local adaptation to different environments. Differentiation between populations within the two regions was negligible. Overall, we found a high number of MHC alleles (50, from 175 individuals). This, together with a tendency for a higher rate of nonsynonymous than synonymous substitutions in the peptide binding sites, and high Tajima's D in certain regions of the gene, suggests a history of balancing selection. MHC variation is often thought to be maintained by some form of balancing selection, but the nature of this selection remains unclear. Our results support the hypothesis that spatial variation in selection regimes contributes to the high polymorphism. [source] Comparative analysis of the within-population genetic structure in wild cherry (Prunus avium L.) at the self-incompatibility locus and nuclear microsatellitesMOLECULAR ECOLOGY, Issue 11 2006SILVIO SCHUELER Abstract Gametophytic self-incompatibility (SI) systems in plants exhibit high polymorphism at the SI controlling S -locus because individuals with rare alleles have a higher probability to successfully pollinate other plants than individuals with more frequent alleles. This process, referred to as frequency-dependent selection, is expected to shape number, frequency distribution, and spatial distribution of self-incompatibility alleles in natural populations. We investigated the genetic diversity and the spatial genetic structure within a Prunus avium population at two contrasting gene loci: nuclear microsatellites and the S -locus. The S -locus revealed a higher diversity (15 alleles) than the eight microsatellites (4,12 alleles). Although the frequency distribution of S -alleles differed significantly from the expected equal distribution, the S -locus showed a higher evenness than the microsatellites (Shannon's evenness index for the S -locus: E = 0.91; for the microsatellites: E = 0.48,0.83). Also, highly significant deviations from neutrality were found for the S -locus whereas only minor deviations were found for two of eight microsatellites. A comparison of the frequency distribution of S -alleles in three age-cohorts revealed no significant differences, suggesting that different levels of selection acting on the S -locus or on S- linked sites might also affect the distribution and dynamics of S -alleles. Autocorrelation analysis revealed a weak but significant spatial genetic structure for the multilocus average of the microsatellites and for the S -locus, but could not ascertain differences in the extent of spatial genetic structure between these locus types. An indirect estimate of gene dispersal, which was obtained to explain this spatial genetic pattern, indicated high levels of gene dispersal within our population (,g = 106 m). This high gene dispersal, which may be partly due to the self-incompatibility system itself, aids the effective gene flow of the microsatellites, thereby decreasing the contrast between the neutral microsatellites and the S -locus. [source] Isolation and characterization of polymorphic microsatellite markers in Amorphophallus paeoniifolius (Dennst.) Nicolson, AraceaeMOLECULAR ECOLOGY RESOURCES, Issue 5 2007E. SANTOSA Abstract Amorphophallus paeoniifolius is an herbaceous perennial tuber crop distributed widely in many Asian countries. We isolated 19 polymorphic loci from A. paeoniifolius using a dual-suppression-PCR technique. These loci provide microsatellite markers with high polymorphism ranging from three to 24 alleles per locus. The observed and expected heterozygosities ranged from 0.521 to 0.854 and from 0.766 to 0.930, respectively. This high allelic diversity indicates that our markers are suitable for a population study in A. paeoniifolius. [source] Development of six microsatellite loci for black mangrove (Avicennia germinans)MOLECULAR ECOLOGY RESOURCES, Issue 3 2006IVANIA CERÓN-SOUZA Abstract We developed six new microsatellite loci for the black mangrove (Avicennia germinans), an important member of wetland communities worldwide. Loci showed moderate to high polymorphism and a survey of four locations [Puerto Rico (Jobos Bay and Luquillo), Mexico, French Guyana] revealed clear regional (and local) population structure. All populations were genetically distinct and the two continental populations showed much higher diversity than the two insular Puerto Rican locations. These loci complement those recently published by Nettel et al. (2005) and promise to be valuable for characterizing local and regional population dynamics in the black mangrove. [source] Isolation of simple and compound polymorphic tetranucleotide microsatellites for the neotropical leaflitter frog Eleutherodactylus ockendeni (Leptodactylidae)MOLECULAR ECOLOGY RESOURCES, Issue 3 2006KATHRYN R. ELMER Abstract Few studies of population structure and genetic diversity exist for frogs in the Amazon of South America, an area renowned for exceptionally high species richness. We isolated seven highly variable tetranucleotide microsatellite loci for the neotropical leaflitter frog, Eleutherodactylus ockendeni using an enrichment method. Three of the repeats are simple, three are compound and one is imperfect. We screened all loci with 175 individuals from one geographical area in the upper Napo of Ecuador and found high polymorphism in all loci (> 14 alleles/locus). These markers are suitable for population genetics studies of E. ockendeni and perhaps other leaflitter frogs of the same genus. [source] Postnatal transcription profile and polymorphism of the ADIPOR1 gene in five pig breedsANIMAL GENETICS, Issue 1 2010M. Stachowiak Summary As a result of its role in energy homeostasis regulation, the ADIPOR1 gene is a candidate for fat deposition, an important production trait, in the pig. The aim of the study was to conduct a comparative analysis of the ADIPOR1 postnatal transcript level, in order to establish its promoter and 5,UTR sequences and to search the gene for polymorphisms. The transcription level was examined in longissimus dorsi and semimembranosus muscles collected from 180 pigs at 60,210 days of age, representing five pig breeds: Duroc, Polish Large White, Polish Landrace, Pietrain and Pulawska. We calculated highly significant breed by age by muscle interaction (P < 0.0001) and breed by muscle interactions (P < 0.01). The 5,UTR and promoter region of the porcine ADIPOR1 gene were amplified for the first time and their sequences were deposited in the GenBank database. In total, 21 novel and two previously described polymorphisms were found in the ADIPOR1 promoter, coding, intronic, 5, and 3, untranslated regions. The only SNP detected in the coding region was a synonymous substitution. Two polymorphisms in 3,UTR (c.*129A>C and c.*536A>G) showed no significant effect on the transcript level. Our results showed a high polymorphism of the ADIPOR1 and a complexity in its transcription level in the studied muscles. This complexity indicates that conclusions based on such studies should be carefully gradated. [source] A New Subfamily of Aphids (Hemiptera, Aphidomorpha) from the Early Cretaceous Lebanese Amber with a Description of the Oldest Apterous MorphsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2010Piotr WEGIEREK Abstract: Aphids are marked by their high polymorphism, but species reported from the Early Cretaceous are known only from alate morphs. The discovery of an apterous adult morph in Lebanese amber and a larva of the same species are very important for the understanding of both the morphological and biological evolution of this insect group at the very early stage of development. Gondvanoaphis estephani new subfamily, new genus and species of the recent aphids family Thelaxidae is described. The characters of the new genus in respect to other genera placed in Thelaxidae are reviewed. The palaeoecological and palaeogeographical data concerning Gondvanoaphis new genus are also discussed. [source] | ||||||||||