Mendelian and non-Mendelian inheritance of newly-arisen chromosome rearrangements

Seven centric shifts and three reciprocal interchanges, all newly-arisen in natural populations, have been tested for their inheritance in the dioecious flowering plant Rumex acetosa. In backcrosses between the heterozygote and standard plants transmissions ranged from 0.36 to 0.85 per gamete for the novel chromosome. The inheritance of only four rearrangements correspond to Mendelian expectations while others exhibited either drive or drag. Drive was observed both through the egg and through the pollen indicating heterogeneity of mechanisms in the generation of non-Mendelian patterns of inheritance. This suggests that accumulation may play a significant role in the establishment of chromosomal variants in natural populations.