The complex Robertsonian system  of Dichroplus pratensis (Melanoplinae,  Acrididae). I. Geographic distribution  of fusion polymorphisms

Bidau, CJ; Belinco, C.; Mirol, P.; Tosto, D.

doi:10.1051/gse:19910501

Cited by 11 publications

(21 citation statements)

References 25 publications

(45 reference statements)

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“…Indeed, in polymorphic populations of D. pratensis, a significant decrease in proximal chiasmata occurs in fusion heterozygotes and homozygotes but not in standards (Bidau, 1990, Tosto & Bidau, 1991 which suggests that the fusions per se exert this effect. This redistribution of crossover sites is of central importance for the maintenance of the polymorphisms.…”

Section: Discussionmentioning

confidence: 99%

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Proximal chiasmata induce non-disjunctional orientation of Robertsonian trivalents in a grasshopper

Mirol

Bidau

1992

Heredity

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The relationship between the symmetry of the meiotic configuration and the type of meiotic orientation (disjunctional and non-disjunctional) in Robertsonian trivalents of Dichroplus pratensis (Melanoplinae, Acrididae) was analysed. The results indicate, first, that neither chromosomal size nor the relation between the length of the chromosomes involved in each fusion are important factors for the determination of the orientation. Second, chiasmata localization, which in turn determines effective inter-centromeric distance, may be central. A high positive correlation between proximal chiasma frequency and non-disjunctional orientation at Prometaphase I and Metaphase I was found. These results are in agreement with the hypothesis that the shorter the inter-centromeric distance the greater is the probability that both centromeres migrate to the same pole. The importance of these results is also discussed in relation to the stability of the polymorphisms in this species.

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Section: Discussionmentioning

confidence: 99%

“…These measurements are shown in Table 2. (Bidau, 1986;Bidau et aL, 1991). Populations are unique regarding frequency, quantity and quality of fusions (usually polymorphic).…”

Section: Introductionmentioning

confidence: 99%

Proximal chiasmata induce non-disjunctional orientation of Robertsonian trivalents in a grasshopper

Mirol

Bidau

1992

Heredity

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“…In the central area (the Pampas) there is a maximum of chromosome variation, including a highly interesting hybrid zone with the formation of multivalents (see Bidau et al, 2003, for a review). The Robertsonian translocations of D. pratensis cause, as usual, a reduced recombination rate due to the proximal and interstitial chiasma frequency reduction in the chromosomes involved in the rearrangements; besides, the loss of independent segregation in anaphase I also impinges on overall genetic recombination (Bidau & Mirol, 1988;Bidau, 1990Bidau, , 1993Bidau et al, 1991). Chromosomal studies of many populations from Argentina (Bidau & Martí, 1995;Martí & Bidau, 1998) was performed on both sexes alike and no difference in chiasma patterns nor of geographic differentiation was noticed.…”

Section: Discussionmentioning

confidence: 99%

Against the central-marginal model: Three cases in chromosomally polymorphic grasshoppers (Orthoptera: Acrididae)

Colombo¹

2012

Eur. J. Entomol.

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Abstract. The central-marginal model is widely accepted in chromosomally polymorphic species of Drosophila. In fact, geographically and ecologically central populations of Drosophila show higher levels of polymorphism for paracentric inversions, whereas marginal populations tend to be monomorphic. This fact has been variously explained. Chromosomal polymorphisms in grasshoppers have also been attributed to show such geographical structuring, as in the case of the South-American grasshopper Dichroplus pratensis Bruner (Orthoptera: Acrididae). However, in three other cases involving Acrididae -Leptysma argentina Bruner, Trimerotropis pallidipennis (Burmeister) and Cornops aquaticum (Bruner), it is clear that chromosomal polymorphisms (sometimes with a wide extension over the Argentine area) do not conform to this pattern, and show instead clear correlations with environmental variables, especially minimum temperature, showing low or null frequencies of the rearrangements at one extreme of the environmental gradient and with high or fixed frequencies at the other. Furthermore, this correlation with temperature might also be true in the case of D. pratensis. These aforementioned examples emphasise the dangers of over-generalization when discussing chromosomal polymorphisms, and suggests that such polymorphisms should be considered very much in a case-specific manner in terms of the particular genetic system under study. 317* Affiliated to CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas).

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“…Its standard karyotype includes 18+X (ǩ)/18+XX (Ǩ) telocentric chromosomes upon which, a Robertsonian (Rb) system produces polytypisms and polymorphisms involving all six large standard autosomes (L1-L6); the other three pairs of autosomes (S7-S9) and the X chromosome are telocentric, and are never involved in Rb polymorphisms (BIDAU and MIROL 1988;BIDAU 1990BIDAU , 1993BIDAU et al 1991;BIDAU and MARTÍ 2002).…”

Section: Introductionmentioning

confidence: 99%

A heterozygous paracentric inversion only detectable through Electron Microscopy, in the grasshopper Dichroplus pratensis (Melanoplinae, Acrididae)

Martí

Bidau

2003

Caryologia

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The complex Robertsonian system of Dichroplus pratensis (Melanoplinae, Acrididae). I. Geographic distribution of fusion polymorphisms

Cited by 11 publications

References 25 publications

Proximal chiasmata induce non-disjunctional orientation of Robertsonian trivalents in a grasshopper

Proximal chiasmata induce non-disjunctional orientation of Robertsonian trivalents in a grasshopper

Against the central-marginal model: Three cases in chromosomally polymorphic grasshoppers (Orthoptera: Acrididae)

A heterozygous paracentric inversion only detectable through Electron Microscopy, in the grasshopper Dichroplus pratensis (Melanoplinae, Acrididae)

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