Further genetic variation at the esterase loci of Drosophila virilis

1984 ◽  
Vol 22 (3-4) ◽  
pp. 323-337 ◽  
Author(s):  
Kendo Tsuno ◽  
N. T. Aotsuka ◽  
Shigeru Ohba
Keyword(s):  
Genetic Variation ◽  
Drosophila Virilis ◽  
Esterase Loci

Seasonal variation and clonal selection in cyclically parthenogenetic rose aphids (Macrosiphum rosae)

1985 ◽  
Vol 27 (2) ◽  
pp. 224-232 ◽  
Author(s):  
L. R. Rhomberg ◽  
S. Joseph ◽  
R. S. Singh
Keyword(s):  
Genetic Variation ◽  
Seasonal Variation ◽  
Clonal Selection ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Polymorphic Loci ◽  
Esterase Loci ◽  
Allozyme Loci ◽  
Macrosiphum Rosae ◽  
Asexual Cycle

Patterns of geographic and seasonal genetic variation were assessed in natural populations of cyclically parthenogenetic rose aphids Macrosiphum rosae (L.). Nine populations were studied for a red–green colour morph and 30 allozyme loci (20 coding for enzymes and 10 for abundant proteins). Genetic variation was found at 5 of 20 enzyme loci (20%); all 10 abundant proteins proved monomorphic. The average heterozygosity was 4.3%. At some polymorphic loci genotypic frequencies showed significant deviations from Hardy–Weinberg proportions. Six local populations from Hamilton, Ontario, were studied for seasonal variation at the colour locus and at two polymorphic esterase loci (Est-2 and Est-4). All three loci showed large changes in genotypic frequencies over the season during the asexual cycle, but only for Est-4 were changes consistent among populations. This locus undergoes a regular seasonal cycle, the directional changes during the asexual phase presumably being balanced by changes during the sexual phase. The frequencies of three-locus genotypes within each locality fluctuated dramatically over the course of a season, reflecting the domination of local infestations by a few particularly successful clones. We speculate that because of such clonal competition followed by extensive migration, much of the selectively neutral variation is purged from aphid populations. The remaining polymorphic loci, which are mostly di- or tri-allelic, are subject to balancing natural selection at the gene or at closely linked loci. The Est-4 in rose aphids is an example of such a selectively maintained polymorphism.Key words: aphids, allozyme variation, seasonal variation, parthenogenesis, clonal selection, population structure.

A comparative analysis of genetic polymorphism in wild and cultivated barley from Tibet using isozyme and ribosomal DNA markers

Genome ◽  
1994 ◽  
Vol 37 (4) ◽  
pp. 631-638 ◽  
Author(s):  
Qifa Zhang ◽  
G. P. Yang ◽  
Xiankai Dai ◽  
J. Z. Sun
Keyword(s):  
Genetic Variation ◽  
Ribosomal Dna ◽  
Wild Barley ◽  
Length Variation ◽  
Spacer Length ◽  
Origin And Evolution ◽  
Centre Of Diversity ◽  
Esterase Loci ◽  
Cultivated Barley ◽  
Comparison Of The Results

This study was conducted to address some of the issues concerning the possible significance of Tibet in the origin and evolution of cultivated barley. A total of 1757 barley accessions from Tibet, including 1496 entries of Hordeum vulgare ssp. vulgare (HV), 229 entries of the six-rowed wild barley H. vulgare ssp. agriocrithon (HA), and 32 entries of the two-rowed wild barley H. vulgare ssp. spontaneum (HS), were assayed for allozymes at four esterase loci. A subsample of 491 accessions was surveyed for spacer-length polymorphism at two ribosomal DNA loci. Genetic variation is extensive in these barley groups, and the amount of genetic diversity in cultivated barley of this region is comparable with that of cultivated barley worldwide. The level of genetic variation of HA is significantly lower than the other two barley groups, and there is also substantial heterogeneity in the level of polymorphism among different agrigeographical subregions. However, little genetic differentiation was detected among the three barley groups (HV, HA, and HS), as well as among different agrigeographical subregions. Comparison of the results from this and previous studies indicated a strong differentiation between Oriental and Occidental barley, thus favoring the hypothesis of a diphyletic origin of cultivated barley.Key words: Hordeum, allozyme, rDNA spacer-length variation, centre of diversity, phylogeny.

THE STUDY OF GENIC VARIATION BY ELECTROPHORETIC AND HEAT DENATURATION TECHNIQUES AT THE OCTANOL DEHYDROGENASE LOCUS IN MEMBERS OF THE DROSOPHILA VIRILIS GROUP

Genetics ◽  
1975 ◽  
Vol 80 (3) ◽  
pp. 637-650
Author(s):  
R S Singh ◽  
J L Hubby ◽  
L H Throckmorton
Keyword(s):  
Genetic Variation ◽  
Drosophila Virilis ◽  
Heat Denaturation ◽  
Virilis Group ◽  
Group A ◽  
Genic Variation ◽  
Drosophila Virilis Group ◽  
Octanol Dehydrogenase

ABSTRACT Heat denaturation studies of three different electrophoretic allozymes of octanol dehydrogenase were performed from 10 species of the Drosophila virilis group. A total of 18 alleles were discovered, and in 3 species in which electrophoretic studies indicated that the locus was monomorphic, heat denaturation showed that the locus was polymorphic. We show that electrophoretic studies underestimate the number of alleles at this locus by a factor of 2.6 in these species. The results are discussed in the light of the continuing controversy over selection and neutral theories of genetic variation.

scholarly journals ESTERASE GENE FREQUENCY DIFFERENCES AND LINKAGE EQUILIBRIUM IN DROSOPHILA VIRILIS POPULATIONS FROM DIFFERENT ECOLOGICAL HABITATS

Genetics ◽  
1975 ◽  
Vol 80 (3) ◽  
pp. 585-594
Author(s):  
Kendo Tsuno
Keyword(s):  
Gene Frequency ◽  
Natural Populations ◽  
Drosophila Virilis ◽  
Habitat Characteristics ◽  
Linkage Equilibrium ◽  
Esterase Loci ◽  
Esterase Gene ◽  
High Degree ◽  
Ecological Habitats ◽  
Null Strain

ABSTRACT In order to study the gene frequency and linkage equilibrium in natural populations, about 5740 chromosomes of Drosophila virilis flies from eight natural populations were analyzed by the null strain method for two linked esterase loci. The frequencies of these esterase genes appear to depend on habitat characteristics rather than on geographical distribution. The populations kept a high degree of linkage equilibrium among them (D =.005).

Sign in / Sign up

Export Citation Format

Share Document