It is clear that the homokaryotype 2st/2st consistently decreased both DT and TL when compared to the 2st/2j* and 2j*/2j* pooled karyotypes.
Thus, the additive effect of, for instance, 2st/2st versus 2j/2j homokaryotypes could be tested as the difference between the two means, and the dominance effect as the difference between the mean value of the 2st/2j heterokaryotype versus the average of the corresponding values for the two homokaryotypes.
- Perhaps the most widely cited example of the SB process is the evolution of new chromosome arrangements, particularly the fixation of those for which the heterokaryotype is less fit than either homokaryotype. This underdominance can result from either improper segregation (as with translocations or centric fusions) or the production of aneuploid gametes through crossing-over (as with pericentric inversions).
Finally, even if drift does fix new arrangements that form deleterious heterozygotes, this will produce increased adaptation only when the new homokaryotype is fitter than its ancestor.
The karyotypes of at least seven [F.sub.1] larvae from each of the wild adults crossed to stock homokaryotypes were determined to infer the karyotypes of the wild adults.
However, heterokaryotypes involving arrangement 2L-1, that is, 2L-1/2L-2 and 2L-1/2L-3, were associated with decreased egg-to-adult development times when compared with 2L/2L homokaryotypes and heterokaryotypes involving 2L, including 2L/2L-1, in populations from the Smoky Mountains.
However, in the British population the acceptance rates varied with karyotype, the [Alpha][Alpha] homokaryotypes
having the highest rates of acceptance, the [Beta][Beta]'s the lowest, and the [Alpha][Beta] heterokaryotypes intermediate.