CORRELATIONS BETWEEN CHROMOSOME SEGMENTS AND FITNESS IN DROSOPHILA MELANOGASTER III. DIFFERENTIAL GENETIC RESPONSES TO ZINC SULFATE AND SELENOCYSTINE

Abstract

Genetic × environmental interactions are examined at an intrachromosomal level in Drosophila melanogaster. With respect to two fitness components, egg production and egg-to-adult viability, evidence is provided that different segments of the X chromosome are affected differently by each of the chemical substances, zinc sulfate and selenocystine. The extent of a segment's effect on a trait is not always parallelled by the extent of its association with that trait's sensitivity to chemical treatment. Both attributes are functions of the genetical background. The degree of dominance of each segment is not always greater in the chemical environments, a finding inconsistent with Parson's concept of "extreme-environment heterosis."