The Evolution and Ecology of Permanent Translocation Heterozygotes

Permanent translocation heterozygotes are known from at least 57 species of flowering plants. They often share certain features of chromosome morphology, though none are universal or required. Many have apparently originated through hybridization of ancestors with different chromosome end arrangements. The population structure of organisms with this genetic system is similar to that of parthenogenetic organisms, i.e., there is relatively little variation within populations and greater amounts of differentiation between populations. Genetic heterozygosity is not necessarily associated with chromosomal heterozygosity. Heterosis may not be necessary to explain the apparent success of permanent translocation heterozygotes in the groups in which it occurs. Permanent translocation heterozygotes are not necessarily weeds, as is often supposed. Their unique genetic system makes them potentially valuable as experimental organisms for the study of ecological genetics.