RECENT EVOLUTION OF UNIFORM TRICHROMACY IN A NEW-WORLD MONKEY

Until recently, New World primates were found to have a single MIL pho topigment gene on the X-chromosome. This arrangement limits males to d ichromatic, or monochromatic color vision. Only females who were heter ozygous for the M/L gene were trichromatic. Recently, an exception has been discovered. Male howler monkeys appear to have more than one M/L pigment gene, and both genders are uniformly trichromatic. We charact erized promoter regions corresponding to two M/L pigment genes in howl ers. Comparison of DNA sequences with those of humans and three specie s of New World primate suggest a recent and independent acquisition of a second M/L gene locus in the howler. (C) 1998 Elsevier Science Ltd. All rights reserved.