DEVELOPMENTS IN THE MEIOTIC ANALYSIS OF HYBRIDS .3. AMENDED MODELS FOR PENTAPLOIDS

Amended models of meiotic behaviour in pentaploid hybrids are presented, which better represent the theory and assumptions about chromosome pairing that such models necessarily incorporate. They correct problems concerning the distribution of chiasmata among and within chromosome configurations inherent in earlier models. In general these analyses give similar interpretations to earlier models but in some cases suggest differing conclusions. The extent of pairing possibilities at the pentaploid level can make it difficult to choose with confidence among the proposed models when the level of chromosome pairing is low.