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Slide #1. Genetic Basis of Reproductive Isolation and of Species Differences Slide #2. 1) Biological Species Concept Slide #3. 2) Reproductive isolation usually evolves in allopatry Slide #4. So what’s the outstanding problem in the genetics of speciation now? Slide #5. Only three known “speciation genes” Slide #6. Questions Slide #7. Two projects Slide #8.     Between-locus incompatibilities Slide #9. The screen:  D. melanogaster-D. simulans hybridization Slide #10. Screen for hybrid lethals:  Slide #11. If only Df males dead…. Slide #12. Deficiency screen Slide #13. Results of Df screen Slide #14. 2L Slide #15. Two worries:A. Artifact of Df stock used?B. True hybrid lethal?Slide #16. 2) Remarkable functional divergence between mel and sim Slide #17. Identifying the genes: Slide #18. Slide 18 Slide #19.     	      Presgraves, Abmayr, Balagopalan and Orr 
<BR>			(2003 Nature 423: 715) Slide #20.   Nucleoporin98-96 Slide #21. Typically conservative, but Slide #22. Adaptive?  Polymorphism survey at Nup96 Slide #23. McDonald-Kreitman Test   Slide #24. Adaptive evolution was early in split of species Slide #25. Summary Slide #26. General conclusions: Slide #27. But what about hybrid sterility? Slide #28. 4-sim hybrid male sterility Slide #29. Little progress . . . Slide #30. New 4-sim chromosome