New evidence of heterosis in naturally occurring inversion heterozygotes in Drosophila pseudoobscura

Levene, Howard; Dobzhansky, Theodosius

doi:10.1038/hdy.1958.3

Cited by 30 publications

(16 citation statements)

References 32 publications

(9 reference statements)

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“…Also, heterosis is not an intrinsic property of inversion heterozygotes and some inversions failed to display heterosis in experimental populations of D. pseudoobscura (LEVENE and DOBZHANSKY 1958). It is clear from our results that inversions in D. melanogaster show relatively weak heterosis in laboratory conditions.…”

Section: Discussioncontrasting

confidence: 41%

Changes of inversion polymorphism in laboratory populations of Drosophila melanogaster

Singh

Das

1992

Journal of Zoological Systematics and Evolutionary Research

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Thirty eight laboratory populations (20 mass cultures and 18 isofemale lines) of Drosophila melanogaster were established from population samples of 20 geographic localities (12 north and 8 south) in India. Each population was kept for 20 generations in the laboratory by transferring 50 flies to fresh culture bottles in every generation after which chromosomal analysis of 100 or more larvae was made. In mass cultures, a decline in the frequency of all the polymorphic inversions detected in natural populations, associated with decreasing heterozygosity, was observed irrespective of their geographic origin or initial frequency. Some inversions were also found to be lost completely in some mass cultures. In order to quantify the degree of genetic divergence between initial and final populations, genetic distance was estimated which was found to be higher in south Indian populations than in those from north which is likely to be due to high frequency of inversions in initial populations from south. However, in isofemale lines, 17inver-sions were found to persist and were maintained at a considerable frequency. Significant deviation from Hardy-Weinberg expectation occurred for 4 inversions and eight Inversion pairs (linked as well as unlinked) showed strong non-random association. These results have been discussed in the term of "drift" and "founder principle" causing changes of inversion polymorphism in laboratory populations of D. melanogaster.

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Section: Discussioncontrasting

confidence: 41%

Changes of inversion polymorphism in laboratory populations of Drosophila melanogaster

Singh

Das

1992

Journal of Zoological Systematics and Evolutionary Research

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“…The second-order selection which would favor certain third chromosomes because of their effects on recombination in other chromosomes would be altogether too weak to account for the rapidity of the changes actually observed. For other data which contradict the conjecture of Epling et al see Levene and Dobzhansky (1958). magnitude of the territory in which the populations have become altered in composition.…”

Section: Discussioncontrasting

confidence: 46%

GENETICS OF NATURAL POPULATIONS. XXVII.: THE GENETIC CHANGES IN POPULATIONS OFDROSOPHILA PSEUDOOBSCURAIN THE AMERICAN SOUTHWEST

Dobzhansky

1958

Evolution

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“…Leven and Dobzhansky (1957) established 27 isofemale lines of D. pseudoobscura and D. persimilis, and maintained them for more than 130 generations. Twenty-six lines initially contained two gene arrangements each, and one line contained three kinds of arrangements for the third chromosome.…”

Section: Discussionmentioning

confidence: 99%

CHROMOSOMAL POLYMORPHISM IN ISOFEMALE LINES AND CAGE POPULATIONS OFDROSOPHILA MELANOGASTER

Inoue

Watanabe

1992

Evolution

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Abstract. -Drosophila melanogaster populations in nature usually carry inversion polymorphisms. When they were transferred to and maintained in the laboratory as large cage populations, frequencies of polymorphic inversions were drastically decreased and finally eliminated. This "cage effect" was observed irrespective of the geographical origin ofthe population or the initial frequency of each inversion. The decrease and elimination of inversions in the cage was not overcome by changing conditions such as medium, temperature, or the number of isofemale lines (40-600) introduced. On the other hand, in the sets of isofemale lines derived from the same geographical origins as the cage populations, each of which was maintained as a small vial population, the inversion frequencies, though decreased from the initial frequencies, were kept at significantly high levels. The cage populations initiated with one or two isofemale lines also maintained the inversion polymorphisms that were as high as vial populations. Natural populations of many Drosophila species are known to be chromosomally polymorphic, the paracentric inversions being the most common (Roberts, 1976). Once the natural populations carrying such polymorphic inversions are transferred to the laboratory and maintained in cages with several thousand flies, they show significant changes in the frequency of inversion chromosomes. Dobzhansky and Pavlovsky (1953) reported gradual changes of inversion frequencies and eventual equilibrium of each inversion in D. pseudoobscura populations. Similarly, using D. ananassae, Tobari and Kojima (1967) and Kojima and Tobari (1969) showed that inversion frequencies eventually reached an equilibrium. On the other hand, Inoue (1979) using D. melanogaster found that all kinds of polymorphic inversions were rapidly eliminated from cage populations.In the present report, we first confirmed the previous observation that inversion polymorphisms were eliminated from cage populations, and then examined various parameters so as to maintain inversion frequencies in laboratory conditions. It was found that inversion polymorphisms were maintained if the populations were kept as the sets of isofemale lines. Moreover, individual isofemale lines in most cases maintained inversion polymorphisms in small vials or even in large population cages. Possible mechanisms for the maintenance of chromosome polymorphisms in natural populations are discussed. MATERIALS AND METHODSD. melanogaster wild flies were collected by sweeping nets or banana traps in various localities (see Tables 1, 2, 5, and 6). Females inseminated in nature were individually kept in glass vials (3 em diameter x 10 em height) to establish isofemale lines. These lines were maintained by mass transfer of about 20-60 flies every 15 days at 25°C. In some experiments flies that were made homozygous for the second chromosomes were employed. These chromosomes were extracted from the natural population by using balanced lethal chromosome stocks with dominant markers, SM] (Cy)/Pm.The cage...

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New evidence of heterosis in naturally occurring inversion heterozygotes in Drosophila pseudoobscura

Cited by 30 publications

References 32 publications

Changes of inversion polymorphism in laboratory populations of Drosophila melanogaster

Changes of inversion polymorphism in laboratory populations of Drosophila melanogaster

GENETICS OF NATURAL POPULATIONS. XXVII.: THE GENETIC CHANGES IN POPULATIONS OFDROSOPHILA PSEUDOOBSCURAIN THE AMERICAN SOUTHWEST

CHROMOSOMAL POLYMORPHISM IN ISOFEMALE LINES AND CAGE POPULATIONS OFDROSOPHILA MELANOGASTER

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