CYTOPLASMIC INCOMPATIBILITY AND MATING PREFERENCE IN COLOMBIAN DROSOPHILA-PSEUDOOBSCURA

MACRAE and ANDERSON observed a large frequency change of mitochondrial DNA (mtDNA) haplotypes in a population initiated with two allopatric strains of Drosophila psuedoobscura, BogER from Colombia and AH162 fro m California. They concluded that mtDNA haplotypes in D. pseudoobscura are not always selectively neutral. NIGRO and PROUT suggested, howeve r, that a maternally transmitted incompatibility system, similar to th e one they observed in two strains of D. simulans from Italy, could ac count for the observed mtDNA frequency changes. SINGH and HALE postula ted that a mating preference between the strains BogER and AH162 in MA CRAE and ANDERSON'S experiment, in the form of negative assortative ma ting, could also account for the mtDNA frequency changes. We report TW O experiments designed to test the hypotheses: that a maternally trans mitted cytoplasmic incompatibility system exists between D. pseudoobsc ura strains BogER and AH162; and, that BogER females mate preferential ly with AH162 males. Our results do not support either hypothesis.