Temporal changes of chromosomal polymorphism in natural populations of Drosophila subobscura

Genetica ◽  
1984 ◽  
Vol 63 (3) ◽  
pp. 181-187 ◽  
Author(s):  
R. De Frutos ◽  
A. Prevosti
Keyword(s):  
Natural Populations ◽  
Chromosomal Polymorphism ◽  
Temporal Changes ◽  
Drosophila Subobscura

scholarly journals Inversion polymorphism in some natural populations of Drosophila pseudoobscura from central Mexico

Genetika ◽  
2007 ◽  
Vol 39 (3) ◽  
pp. 343-354 ◽  
Author(s):  
Víctor Salceda ◽  
Judith Guzmán ◽  
Olga Olvera
Keyword(s):  
Relative Frequency ◽  
Polytene Chromosomes ◽  
Natural Populations ◽  
Chromosomal Polymorphism ◽  
Drosophila Pseudoobscura ◽  
Central Mexico ◽  
The Third ◽  
Grand Total ◽  
Different Populations ◽  
Single Larva

Samples of D. pseudoobscura were taken in seventeen localities in Central Mexico inside the parallels 18o - 20o N, with the purpose of determine the chromosomal polymorphism in the third of the different populations of this species. From each captured female a single larva of its offspring was taken, its salivary glands extracted and stained with a solution of aceto orcein to observe the polytene chromosomes. From these smears the corresponding karyotype of each larva was determined, keeping a record of them. With the information gathered the relative frequency of each one of the fourteen different inversions found was calculated. A grand total of 1894 third chromosomes were analyzed. The fourteen different inversions found are equivalent to a 34.1 % of the total chromosomal variation of the species. The most abundant inversions found were: TL 50.6 %, CU 27.2 5, SC 9.1 % and EP 5.5 %; the remaining ten inversions detected are in general grounds rare ones with variable relative frequencies depending on the locality. Analysis of the predominant inversions for each population was done. The presence of West-East gradients is reported, even if in cases not so well defined, since as one moves in a particular direction the ups and downs in relative frequency for the alternating pairs TL-CU; TL-SC in the western populations and TL-CU in the eastern ones were observed. The assignment of each population to a particular race was also done, and such a way we were able to recognize three different races coexisting in the area of study.

scholarly journals Micro-geographic variation of inversions in natural populations of Drosophila pseudoobscura

Genetika ◽  
2006 ◽  
Vol 38 (2) ◽  
pp. 97-105 ◽  
Author(s):  
Víctor Salceda ◽  
José Espinoza-Velazquez
Keyword(s):  
Geographic Variation ◽  
Population Sample ◽  
Polytene Chromosomes ◽  
Natural Populations ◽  
Chromosomal Polymorphism ◽  
Drosophila Pseudoobscura ◽  
Natural Habitats ◽  
San Luis ◽  
San Luis Potosi ◽  
San Luis Potosí

Chromosomal polymorphism for the third chromosome in Drosophila pseudoobscura has been widely studied for genetic variation in different environments or locations far apart. However, there is less information regarding sites geographically near one another. Targeting on possible micro-geographic variation in the species, a serial study was done on 12 Mexican populations grouped in four regions, including locations in Durango (DU), the border area of Guanajuato-San Luis Potosi states (GP), Chiapas (CH) and Saldilo (SA). Flies were trapped in their natural habitats using fermenting bananas as bait. They were individually cultivated in the laboratory for larvae production. In a given population sample several flies were cultivated together but only one larva per culture provided salivary tissue to observe polytene chromosomes. Gene arrangements or inversions were identified and frequencies were calculated. A total of 767 third chromosomes were studied and 11 different inversions detected. The type and relative frequencies of the arrangements varied among regions. From the 11 inversions observed, 10 were found in Durango, five in Guanajuato-San Luis Potosi and Chiapas, and eight in Saltillo. The inversion frequencies in the Durango locations varied in four cases, but only one in Chiapas, three cases in Guanajuato-San Luis Potosi, and five in Saltillo. It was also observed that there were geographical gradients for inversions within regions as follows: four arrangements in Saltillo and Durango, three in Guanajuato-San Luis Potos? and one in Chiapas. Moreover, all four regions studied showed evidences for micro-geographical variation. Nevertheless, more studies are needed to elucidate the relevance of the inversion frequencies changes in neighboring populations and also any seasonal-annual frequencies observed in the locations studied here.

scholarly journals Chromosomal polymorphism in Drosophila subobscura populations from Barcelona (Spain)

1964 ◽  
Vol 5 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Antonio Prevosti
Keyword(s):  
Chromosomal Polymorphism ◽  
Drosophila Subobscura ◽  
Marginal Populations ◽  
Seasonal Differences ◽  
Present Evidence ◽  
Two Populations

1. Chromosomal polymorphism in two populations of D. subobscura from Barcelona has been analysed and compared with the polymorphism which has been reported from other populations.2. In spite of microclimatic differences between the Barcelona sites, there is no evidence of differences in the frequency of inversion types nor of seasonal differences within one of these sites.3. Regularities in the array of frequencies of chromosomal types in Barcelona and other populations suggest that the polymorphism is mainly adaptive although there is also evidence of differences due to distance which are not obviously associated with differences in habitat.4. In general the index of free recombination gives higher values in the marginal populations of D. subobscura, but further data are needed to arrive at a definite conclusion on this point since the present evidence is rather ambiguous.

TRIPLOIDY IN NATURAL POPULATIONS OF THE BLACK FLY CNEPHIA MUTATA (MALLOCH)

1959 ◽  
Vol 37 (4) ◽  
pp. 571-589 ◽  
Author(s):  
V. R. Basrur ◽  
K. H. Rothfels
Keyword(s):  
Salivary Gland ◽  
Banding Pattern ◽  
Natural Populations ◽  
Chromosomal Polymorphism ◽  
Genetic Exchange ◽  
Black Flies ◽  
Female Progeny ◽  
Southern Ontario ◽  
Black Fly ◽  
Standard Sequence

Populations of Cnephia mutata in southern Ontario contain both diploid and triploid individuals. The diploid form is bisexual and lacks chromosomal polymorphism except for a rearrangement involved in its cytological sex determining mechanism. The triploids are parthenogenetic; they produce female progeny only and are highly heterozygous for inversions. The banding pattern of the salivary gland chromosomes of diploids and triploids is very similar; the identical standard sequence occurs in both. The complete lack of autosomal inversions in diploids contrasted with their abundance in triploids indicates that effective genetic exchange does not occur between the two forms; they are reproductively completely isolated, although opportunity for cross-mating would seem to exist. The origin of polyploid parthenogenetic forms in black flies is discussed and the view is favored that they are autopolyploid and automictic.

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