Constraints upon the organisation and evolution of chromosomes in Allium

摘要: In terms of chromosome morphology, karyotype organisation, taxonomy and genetic relationship as judged from pairing in the Fl hybrid, A. cepa A.fistulosum are two closely related species. But large variation nuclear DNA amounts has occurred during evolution A comparison molecular composition species confirmed that excess acquired was predominantly repetitive sequences (sequences which do not encode information). However, its distribution within complements equal all chromosomes irrespective differences size. The even suggests strong constraints underlying evolutionary changes genome organisation. nature is discussed, it shown such can influence direction speciation.