Genome size and constitutive heterochromatin in Hilobates muelleri and Symphalangus syndactylus and in their viable hybrid

Genome size was measured as the amount of Feulgen-stained DN A in six species of the family Hylobatidae and in a hybrid of the gibbon t Hylobates muelleri) and siamang (Symphalangus syndactylus). The family, on the w hole, exhibits a w ider range of genome sizes than pongids: In particular, the siamang has about 15% more DNA than the 44-chromosome Hylobates spe cies of the “lar” group. Quantitative analysis of C-heterochromatin in hybrid metaphases showed that the difference in genome size of the parental species correlates with the amount of C-band-positive material. Hylobatids are the only group of primates in which karyotype diversification has taken place with a massive quantitative change in constitutive heterochromatin.