Experiments using the strengths of the natural biological design provided by parthenogenetic Drosophila will be conducted to 1) identify the level of genetic organization which acts as the unit of genetic selection independent of influences by other such units and 2) determine the role and types of allele interactions between loci which may enter into the organization of such units. A quantitative study of the selective forces operating at the genomic levels, inter-chromosomal level, and intra-chromosomal level will be conducted. Measures of the interactions among marker loci and between these loci and various genetic background will be estimated and tested using statistical methodology developed by this laboratory. The experiments outlined utilize one of the few bilogical systems available in which quantitative studies can be done to describe the genetic unit of selection.