GAMETIC DISEQUILIBRIUM BETWEEN ALLOZYME LOCI AND SEX-CHROMOSOMES IN THE GENUS RHAGOLETIS

Strong gametic disequilibrium between allozyme loci and sex chromosome s exists in natural populations of four Rhagoletis species, and weak d isequilibrium exists in two other species. The disequilibrium is possi ble because of (1) extensive homology of X and Y chromosomes and (2) r estricted crossing over in male Rhagoletis. One of the species display ing strong disequilibria, R. suavis, must be female heterogametic, alt hough direct cytogenetic evidence is not yet available. Forces respons ible for the evolution of the disequilibrium are discussed.