• Population genetics ofDrosophila nasuta nasuta, Drosophila nasuta albomicana and their hybrids II. Coassociation of parental chromosomes in the hybrid populations

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    • Keywords


      Coadaptation; heterokaryo types; speciation

    • Abstract


      D. n. nasuta (2n=8) andD. n. albomicana (2n=6), the chromosomal races of thenasuta subgroup have mutual open genetic systems. Hybrid populations are completely fertile. By utilising fixed inversion differences in second and third chromosomes, the extent of coassociation of parental chromosomes in the gene pool of the hybrids have been estimated. There is a significant decline in the Inversion polymorphism of the second chromosome, while in the third chromosome both the parental and the hybrid associations are equally frequent. The reduction in the frequency of heterokaryotypes in the second chromosome is due to the establishment of different coadapted systems in the parental chromosomes which has been favoured by selection. This does not occur in the third chromosome. This dochotomy of differential coadaptation within the elements of the same genotype is the first of its kind and the implications of these findings are discussed.

    • Author Affiliations


      M R Rajasekarasetty1 N B Krishnamurthy1 H A Ranganath1

      1. Department of Post-Graduate Studies and Research in Zoology, University of Mysore, Manasa Gangotri, Mysore - 570 006
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