Abstract:
Inter and intrachromosomal viability interactions
have been detected in a few experimental studies. Computer
simulations and analytical models have led to postulation
of nonadditivity of gene action. This study reports
evidence of strong nonadditive interactions between the
arms of the metacentric second chromosome of Drosophila
melanogaster. Mean viability for 40 homozygous lines of
the second chromosomes was 0.720+0.265 • Mean viability
for 40 half homozygous second chromosomes was 0.928!O.)10 •
Significant heterogeneity among and within lines was
found in both groups of chromosomes, as well as a highly
significant viability difference between the two groups.
Comparison of observed viabilities with the expected
values, according to the theories of additive and multi -
plicative gene action. was made for both groups. Highly
significant departures from the expected values were found
for over 90% of the lines in both groups of chromosomes,
for both additive and multiplicative models of gene action.
