Competition Among Genotypes in Tribolium castaneum at Varying Densities and Gene Frequencies (The Sooty Locus)

Abstract

Adult survivorship and dry weight were studied in cultures started from eggs in Hardy-Weinberg proportions of .25, .5, and .75 sooty. At 100/g., overall survivorship was markedly lower than at the lower 3 densities (5/g., 20/g., 50/g.). The survivorship performance of the heterozygote improved as the frequency of sooty increased. Weights of adults were highest at 20/g. In mixed cultures, the weights were ranked as follows sooty [image] wild type > heterozygote. Gene frequency of sooty had a marked effect on weights of wild type and heterozygote adults and some effect on mutant homozygotes. An approximation to a linear function is obtained when weights were plotted as a function of the proportion of heterozygotes and homozygous mutants combined. Heterozygotes are intolerant to crowding, especially with their own genotype. Weight relations among genotypes depend on whether the beetles were reared in pure or mixed cultures. Thus, the performance of genotypes when interacting with other genotypes cannot be entra-polated from their performance in pure culture. The facilitation and interaction among genotypes is discussed from the general point of view of considering quality as well as frequencies of genotypes as comprising part of the milieu of any individual.