SPONTANEOUS CROSSING OVER IN THE MALES OF <i>DROSOPHILA</i> <i>ANANASSAE</i>: TWO-WAY SELECTION FOR RECOMBINATION VALUES

Abstract

Wide individual variation in the frequency of female crossing over in D. melanogaster was observed in some early experiments (Gowen 1919). In order to study the factors responsible for this variation, experiments were performed to select strains with high and low crossover values.Ineffective two-way selection led Gowen (1919) to conclude that modifying genes are not responsible for the individual variations.On the other hand, Detelfsen and Roberts (1921) could reduce recombination frequency in females of D. melanogaster significantly by selection and proposed that crossing over is controlled by multiple incompletely dominant factors. Levine and Levine (1955) reported that variable crossing over arises in different strains of D. pseudoobscu ra and thus provided evidence in favour of genotypic control of crossing over.Recent attempts to obtain further evidence by using artificial selection were unsuccessful.In females of D. melanogaster, Parsons (1958) selected for increased recombination for nine generations. Although there was a rise in amount of recombination in the region adjacent to the centromere, little alteration was noted over the whole selected segment. Acton (1961) was unsuccessful in reducing recombination frequency even after selecting for 23 generations in the females of the same species. In D. ananassae, Mukherjee (1961) selected spontaneous male recombination values in the third chromosomes and appeared successful in getting a low line within a short period of eight generations, perhaps by picking up an inversion. Ray-Chaudhuri and Kale (1967a, b) studied spontaneous male crossing over in the second chromosomes of D. ananassae.Great individual variation in crossover values of individual males was observed. This is the basis of the two-way selection experiments reported in this paper. MATERIAL AND METHODThe wild stock, as, was collected from Calcutta (India) and was inbred in the laboratory for nearly 300 generations.The marked stock was a second chromosome recessive stock.The markers and their position as descried by Ray-Chaudhuri et al. (1959) are, cu (curled wings), b (black body) and se (sepia eyes). According to the female recombination data, the distance between cu and b is approximately 10 map units and between b and se, 46 map units.The experiments were performed at 74° ±4° F. A random sample of 40 wild males was collected within four hours after eclosion to

SPONTANEOUS CROSSING-OVER IN THE MALE OF <i>DROSOPHILA ANANASSAE</i>

“…Levine and Levine (1955) Kale (1968) reported some responses to selection in male crossing-over of D. ananassae. In our laboratory, selection experiments have not been done.…”

“…Another case of spontaneous crossing-over in the male was reported in the same species from India (Mukherjee 1961; Ray-Chaudhuri and Kale 1966;Kale 1968Kale , 1969.…”

ON THE ETHOLOGICAL DIFFERENTIATION OFDROSOPHILA ANANASSAEANDDROSOPHILA PALLIDOSAIN SAMOA

“…Backcross hybrids were obtained from crosses involving F1 hybrid males only since it would be possible to know the X chromosome genotype precisely and to expect that little, if any, crossingover between homologs would have occurred in the heterozygous Fl. One cannot be ab-solutely certain about the non-existence of recombinant chromosomes in D. ananassae sperm since some strains of this species have been found in which genetic crossingover occurs in the spermatocytes (Kikkawa, 1937;Moriwaki, 1937;Mukherjee, 1961;Kale, 1968;Hinton, 1970). Meiotic crossingover in males is unknown in any other species of Drosophila.…”

Enhancer and suppressor system of male recombination in Drosophila ananassae.

“…In addition, modifiers of male recombination located on the X chromosome as well as cytoplasmic elements were noted by Hinton (1974). It has also been inferred that a polygenic system can account for the recombination in the male (Mukherjee 1961;Kale 1968;Moriwaki et al 1970) . Recently, an effect of the Y chromosome on male recombination was demonstrated by Moriwaki et al (1979).…”