EVIDENCE FOR EXTENSIVE GENETIC DIFFERENTIATION BETWEEN THE SEX-RATIO AND THE STANDARD ARRANGEMENT OF DROSOPHILA PSEUDOOBSCURA AND D. PERSIMILIS AND IDENTIFICATION OF HYBRID STERILITY FACTORS

Chung-I Wu ¹ and Andrew T. Beckenbach ²

¹ Institute of Animal Resource Ecology, The University of British Columbia, Vancouver, British Columbia, Canada
² Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada

This study deals with sex-ratio genes tightly linked within the Sex-Ratio inversion. By taking advantage of the fact that the Sex-Ratio chromosome of Drosophila persimilis [SR(B)] is homosequential to the Standard chromosome of D. pseudoobscura [ST(A)], we carried out two reciprocal introgression experiments. Individual segments of SR(B) or ST(A) were introgressed into the genome of D. pseudoobscura or D. persimilis, respectively. Males possessing a hybrid SR(B)-ST(A) X chromosome and a genetic background derived from either of the two species were tested for fertility and sex-ratio expression.—It was found that, in terms of the meiotic drive genes, the Sex-Ratio chromosome differs extensively from the Standard chromosome. Because recombinations of these genes result in a complete loss of sex-ratio expression, this finding lends strong support to the hypothesis of gene coadaptation. Coadaptation, in this context, is the advantage of being transmitted preferentially. In light of this finding, the evolution of the sex-ratio system in these two sibling species is discussed.—Introgression experiments also yielded information about hybrid sterility. With reciprocal introgression, sterility interactions were found to be "asymmetric." The asymmetry is fully expected from the viewpoint of evolution of postmating reproductive isolation.

This article has been cited by other articles:

				J. M. Good, M. D. Dean, and M. W. Nachman A Complex Genetic Basis to X-Linked Hybrid Male Sterility Between Two Species of House Mice Genetics, August 1, 2008; 179(4): 2213 - 2228. [Abstract] [Full Text] [PDF]

				B. A. Payseur and M. Place Searching the Genomes of Inbred Mouse Strains for Incompatibilities That Reproductively Isolate Their Wild Relatives J. Hered., March 1, 2007; 98(2): 115 - 122. [Abstract] [Full Text] [PDF]

				C. Montchamp-Moreau, D. Ogereau, N. Chaminade, A. Colard, and S. Aulard Organization of the sex-ratio Meiotic Drive Region in Drosophila simulans Genetics, November 1, 2006; 174(3): 1365 - 1371. [Abstract] [Full Text] [PDF]

				B. A. Payseur and H. E. Hoekstra Signatures of Reproductive Isolation in Patterns of Single Nucleotide Diversity Across Inbred Strains of Mice Genetics, December 1, 2005; 171(4): 1905 - 1916. [Abstract] [Full Text] [PDF]

				H. A. Orr and S. Irving Segregation Distortion in Hybrids Between the Bogota and USA Subspecies of Drosophila pseudoobscura Genetics, February 1, 2005; 169(2): 671 - 682. [Abstract] [Full Text] [PDF]

				S. Richards, Y. Liu, B. R. Bettencourt, P. Hradecky, S. Letovsky, R. Nielsen, K. Thornton, M. J. Hubisz, R. Chen, R. P. Meisel, et al. Comparative genome sequencing of Drosophila pseudoobscura: Chromosomal, gene, and cis-element evolution Genome Res., January 1, 2005; 15(1): 1 - 18. [Abstract] [Full Text] [PDF]

				M. Slotman, A. della Torre, and J. R. Powell The Genetics of Inviability and Male Sterility in Hybrids Between Anopheles gambiae and An. arabiensis Genetics, May 1, 2004; 167(1): 275 - 287. [Abstract] [Full Text] [PDF]

				C. Montchamp-Moreau and M. Cazemajor Sex-Ratio Drive in Drosophila simulans: Variation in Segregation Ratio of X Chromosomes From a Natural Population Genetics, November 1, 2002; 162(3): 1221 - 1231. [Abstract] [Full Text] [PDF]

				M. Kovacevic and S. W. Schaeffer Molecular Population Genetics of X-Linked Genes in Drosophila pseudoobscura Genetics, September 1, 2000; 156(1): 155 - 172. [Abstract] [Full Text]

				T. Takano-Shimizu Genetic Screens for Factors Involved in the Notum Bristle Loss of Interspecific Hybrids Between Drosophila melanogaster and D. simulans Genetics, September 1, 2000; 156(1): 269 - 282. [Abstract] [Full Text]

				M. Turelli and H. A. Orr Dominance, Epistasis and the Genetics of Postzygotic Isolation Genetics, April 1, 2000; 154(4): 1663 - 1679. [Abstract] [Full Text]

				M. Cazemajor, D. Joly, and C. Montchamp-Moreau Sex-ratio Meiotic Drive in Drosophila simulans Is Related to Equational Nondisjunction of the Y Chromosome Genetics, January 1, 2000; 154(1): 229 - 236. [Abstract] [Full Text]