Search results for "population genetics."
showing 10 items of 248 documents
The Stock Genetic Structure of Two Sparidae Species, Diplodus vulgaris and Lithognathus mormyrus, in the Mediterranean Sea.
2003
Abstract Polyacrilamide gel electrophoresis (PAGE) of allozymes was used to investigate the intraspecies genetic variation and the genetic stock structure of Diplodus vulgaris and Lithognathus mormyrus captured from eight localities in the Mediterranean Sea. Twenty-two and 20 putative enzyme-coding loci were examined, respectively, in D. vulgaris and L. mormyrus . Polymorphic loci at the 95% level were used to assess the allozyme variability in D. vulgaris ( AAT-2 ∗ , EST-1 ∗ , GLDH ∗ , PEPB-2 ∗ , PGI-2 ∗ , PGM ∗ , SDH ∗ ) and L. mormyrus ( AAT-2 ∗ , EST-1 ∗ , GLDH ∗ , MDH-2 ∗ , PGI-2 ∗ , PGM ∗ ). The proportion of polymorphic loci in both species ranged from 0.31 ( D. vulgaris ) to 0.30 ( …
Isolation of seven polymorphic microsatellites in Ophioblennius atlanticus atlanticus (Perciformes, Blenniidae)
2005
We isolated and characterized seven polymorphic microsatellite loci of Ophioblennius atlanticus atlanticus (Valenciennes, 1836) using an optimized protocol to construct and screen a microsatellite-enriched genomic library. The analysis of variability was performed in 16 specimens from Faial Island (Azores, Portugal). The mean number of alleles was 8.71 ± ± ± 2.43 and the level of expected heterozygosity ranged from 0.764 to 0.903. The total exclusionary probabilities using these loci for the first and the second parent were 0.985 and 0.998, respectively, suggesting that these microsatellites are a useful tool for large-scale parentage analysis.
Investigations on the genetics and population genetics of the ?2 polymorphism
1970
The results of studies on 49 families with 107 children and various populations of Caucasoid, Negroid and Mongoloid origin concerning the genetics and population genetics of the β2-glycoprotein I polymorphism are reported. In general the genetical model proposed by Cleve (1968) is confirmed: two autosomal alleles BgN and BgD controlling the phenotypes Bg N-N, Bg N-D and Bg D-D. However, divergences from this model were found in two families. They indicate the assumption of non-genetic factors influencing the phenotype expression rather than more complicated genetical control mechanisms. Within Caucasoid populations phenotype and gene frequencies show almost a homogeneous distribution. This …
RAPD variation within and among natural populations of outcrossing willow-leaved foxglove (Digitalis obscura L.)
1999
Random amplified polymorphic DNA (RAPD) markers were used to assess levels and patterns of genetic diversity in Digitalis obscura L. (Scrophulariaceae), an outcrossing cardenolide-producing medicinal plant species. A total of 50 plants from six natural populations on the Iberian Peninsula were analysed by six arbitrarily chosen decamer primers resulting in 96 highly reproducible RAPD bands. To avoid bias in parameter estimation, analyses of population genetic structure were restricted to bands (35 of 96) whose observed frequencies were less than 1–3/n in each population. The analysis of molecular variance (AMOVA) with distances among individuals corrected for the dominant nature of RAPDs (g…
Genome-wide analysis identifies potentially causative genes explaining the phenotypic variability in Pinzirita sheep
2019
Genome-wide analysis identifies potentially causative genes explaining the phenotypic variability in Pinzirita sheep
Unmasking frequency-dependent selection in tri-cultures of Drosophila melanogaster.
1989
Larval-to-adult viability was measured for three strains of Drosophila melanogaster: a wild strain and two eye colour mutant strains (cardinal and sepia) starting from seventy different genotypic compositions. Analyses of a sub-set of the data (not considering all genotypic frequencies) demonstrate frequency-dependence in the three strains. These results suggest that in this experiment, frequency-dependent selection may be masked by other selective forces, only being apparent when specific analyses are carried out.
Intra- and intergenotypic competition in Drosophila melanogaster: effects of density on larval survival and rate of development
1986
We have examined the effects of density and frequency in the larval competition of Drosophila melanogaster by measuring three fitness components: viability (V), mean development time (MDT) and a combination of these two (E). We have detected (contrary to most published results) non-linear effects of density in single-genotype cultures; in addition, different functions are required to describe the density effects below and above the optimal density. Frequency has also non-linear effects in the two-genotype cultures. Only one polymorphic equilibrium frequency, which is stable, occurs with respect to V; but two polymorphic equilibria, one stable and one unstable, exist with respect to E. The r…
The STR252-IVS10nt546-VNTR7 phenylalanine hydroxylase minihaplotype in five Mediterranean samples.
1997
IVS10nt546 (IVS10nt-11g→a) is the most common molecular defect of the phenylalanine hydroxylase gene causing phenylketonuria in Mediterranean populations. Previous studies have proposed various and alternative hypotheses concerning the geographical origin and pattern of diffusion of this mutation in this area. In this study, this issue was re-examined on a large sample (149) of “Mediterranean” IVS10nt546 mutant alleles analysed with multiallelic intragenic polymorphisms. The analysis of intragenic microsatellite (STR) and minisatellite (VNTR) polymorphisms shows allelic heterogeneity of the IVS10nt546 mutation. Eight STR and three VNTR alleles were found in association with the splicing def…
Molecular markers for systematic identification and population genetics of the invasive Ponto-Caspian freshwater gammarid Dikerogammarus villosus (Cr…
2006
The Ponto-Caspian amphipod, Dikerogammarus villosus, is an invasive species of many European rivers. First, we show that size difference of nrDNA ITS1 allows discriminating D. villosus from Dikerogammarus bispinosus, a closely related but morphologically hardly distinguishable species. Second, we present two types of polymorphic markers for D. villosus, three microsatellites and two single nucleotide polymorphisms (SNPs) of mtDNA COI gene, which were scored by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP). These markers will be very useful in studying population genetics of D. villosus.
Mitochondrial Dna Sequence Variation among Geographic Strains of Diamondback Moth (Lepidoptera: Plutellidae)
1997
We examined genetic variation among 6 geographic strains of diamondback moth, Plutella xylostella (L.), using 365 base pairs of the mitochondrial gene encoding cytochrome oxidase I (COI). No sequence variation was detected within 5 of the 6 strains; 1 strain contained 2 haplotypes that differed by a single base substitution (0.27%). Sequence differences between strains of diamondback moth from Hawaii, the Philippines, and Pennsylvania ranged from 0 to 0.82%. With one exception, base pair substitutions among strains resulted in synonymous codons and did not alter amino acid sequence. Genetic divergence between strains of diamondback moth was not correlated with geographic distances between t…