1. 1. Birky, C. W. Jr Science 222, 468–475 (1983). 2. Werren, J. H., Skinner, S. W. & Charnov, E. L. Nature 293, 467–468 (1981). 3. Werren, J. H. & van den Assem, J. Genetics 114, 217–233 (1986). 4. Wylie, H. G. Can. Ent. 98, 645–653 (1966). 5. Werren, J. H. Evolution 37, 116–124 (1983). 6. Charnov, E. L. The Theory of Sex Allocation (Princeton University Press, 1982). 7. Werren, J. H. Science 208, 1157–1160 (1980). 8. Skinner, S. W. Science 215, 1133–1134 (1982). 9. Skinner, S. W. Genetics 109, 745–754 (1985). 10. Werren, J. H., Skinner, S. W. & Huger, A. M. Science 231, 990–993 (1986). 11. Skinner, S. W. thesis, Univ. Utah (1983). 12. Sears, B. B. Stadler Symp. 15, 119–138 (1983). 13. Ryan, S. L. & Saul II, G. B. Molec. gen. Genet. 103, 24–36 (1968). 14. Saul, G.– B., Whiting, P. W., Saul, S. W. & Heidner, C. A. Genetics 52, 1317–1327 (1965). 15. Nur, U. R. Ent. Soc. Lond. Symp. 10, 97–117 (1980). 16. Bull, J. J. The Evolution of Sex Determining Mechanisms (Benjamin, Menlo Park, California, 1983). 17. Mulcahy, D. & Pascho, R. J. Science 225, 333–335 (1984). 18. Dawkins, R. The Selfish Gene (Oxford University Press, 1976). 19. Doolittle, W. F. & Sapienza, C. Nature 284, 601–603 (1980). 20. Orgel, L. E. & Crick, F. H. C. Nature 284, 604–607 (1980).