Abstract

The DNA content of 58 species of primates out of the approximately 180 described (Chiarelli, 1972), belonging to 29 out of the 54 existing genera is reported. The amount of nuclear DNA was measured microdensitometrically on lymphocytes of peripheral blood submitted to the Feulgen reaction. Genome size was found to range from 4.7 to 10.9 pg (respectively 65% and 150% the value observed in man, considered to be 7.3 pg). Generally speaking, in the group of species studied, no correlation was found between Feulgen-DNA content and chromosome number. At any rate, three different situations were revealed: (1) the lemurs of Madagascar, with a fairly low and constant DNA content and a highly variable chromosome number; (2) the genus Cercopithecus, showing a quite variable DNA content, occasionally related to the chromosome number; (3) the subfamily Papiinae, in which both the chromosome number and the DNA content appear exceptionally constant. The hypothesis of a different influence of selective pressure on the two parameters, in relation to different environments, is also discussed. According to this hypothesis, these differences would have led to the development of cytologic conditions which are the reflection of different evolutionary pathways.