Genetics of Natural Populations. Xxviii. The Magnitude of the Genetic Load in Populations of Drosophila Pseudoobscura

The Estimation of Relative Fitness of Drosophila Populations. II. Experimental Evaluation of Factors Affecting Fitness

“…Dobzhansky and Wallace (1953), and Lerner ( 1954) suggested that heterozygotes are more uniformly successful in a variety of environments than are homozygotes, while Lewontin (1957) generalized by suggesting that greater mean fitness over a number of environments will be generally associated with low variance in fitness. Negative correlations between mean viability (determined over a number of environments) and variability were found by Dobzhansky and Levene (1955), Bonnier andJonsson (1957), andSpassky, Spassky, Pavlovsky, Krimbas, Krimbas, andDobzhansky ( 1960).…”

The Genetic Structure of Natural Populations of Drosophila Melanogaster. I. Spontaneous Mutation Rate of Polygenes Controlling Viability

“…In the present experiment, we did not use the Cy-Pm method (WALLACE 1956), because classification would be too tedious and the error variances estimated by this method would be larger than those by the Cymethod ( SPASSKY, SPASSKY, PAVLOVSKY, KRIMBAS, KRIMBAS and DOBZHANSKY 1960). Although the viability of Cy/+, as the standard in the Cy-technique might vary to some extent from line to line owing to the independent occurrence of mutations, the amount of variation is negligible compared with that in the homozygote +i/+i.…”

FITNESS OF KARYOTYPES IN DROSOPHILA PSEUDOOBSCURA

“…Presumably well suited in various combinations with other third chromosomes for the natural conditions, these chromosomes were immediately tested in our system. Here they had somewhat lower egg-to-adult viabilities than other, similarly tested laboratory-stock chromosomes which hed had some opportunity to "acclimatize" (SPASSKY et al 1960;STRICKBERGER 1972). In our experiment; outbreeding produced homokaryotypes and heterokaryotypes both of which were highly significantly superior to the Inbred lines.…”