Interaction between Complexes as Evidence for Segmental Interchange in Oenothera

Abstract

It is possible to predict the arrangement of chromosomes during dia-kinesis in certain complex-combinations on the theory of segmental interchange, using a combination of cytological and genetical data. The cytological data consist of the facts already known regarding chromosome arrangements in species and hybrids of the genus, the genetical data include facts in regard to differences in linkage relations in different hybrids. Definite predictions have been made as to chromosome arrangement in the case of 5 hybrid combinations, and less definite predictions have been made in 3 other cases. Of the 5 in which definite predictions have been made, 3 were already known cytologically when the predictions were worked out, and the predictions agreed with the facts; one has since been ascertained to be in line with the prediction, and one still remains to be determined. The possibility of successfully predicting the chromosome configurations in various complex-combinations on the basis of segmental interchange leads to the conclusion that the phenomenon of segmental interchange is probably at the basis of circle formation in Oenothera.