WIDESPREAD OCCURRENCE OF B-CHROMOSOMES

Results are presented of a survey of the occurrence of B-chromosomes in plants and animal species. In plants, B-chromosomes have been found in over 1000 angiosperms, as well as in some gymnosperms and mosses. They occur just as frequently in polyploids as in diploids. In the animal kingdom they are known in more than 260 species, mostly belonging to the Insecta. They are also found in nineteen mammals. The distribution of B's among the different taxonomic groupings appears to be quite random.