IN-SITU HYBRIDIZATION (FISH) MAPS CHROMOSOMAL HOMOLOGIES BETWEEN ALOUATTA BELZEBUL (PLATYRRHINI, CEBIDAE) AND OTHER PRIMATES AND REVEALS EXTENSIVE INTERCHROMOSOMAL REARRANGEMENTS BETWEEN HOWLER MONKEY GENOMES

We hybridized whole human chromosome specific probes to metaphases of the black-and-red howler monkey Alouatta belzebul in order to establis h chromosomal homology between humans and black-and-red howlers. The r esults show that the black-and-red howler monkey has a highly rearrang ed genome and that the human chromosome homologs are often fragmented and translocated. The number of hybridization signals we obtained per haploid set was 40. Nine human chromosome probes gave multiple signals on different howler chromosomes, showing that their synteny is distur bed in A. belzebul. Fourteen black-and-red howler autosomes were compl etely hybridized by one human autosomal paint, six had two signals, th ree had three signals, and one chromosome had four signals. Howler chr omosomes with multiple signals have produced 12 chromosomal syntenies or hybridization associations which differ from those found in humans: 1/2, 2/20, 3/21, 4/15, 4/16, 5/7, 5/11, 8/18, 9/12, 10/16, 14/15, and 15/22. The hybridization pattern was then compared with those found i n two red howler taxa and other mammals. The comparison shows that eve n within the genus Alouatta numerous interchromosomal rearrangements d ifferentiate each taxa: A. belzebul has six unique apomorphic associat ions, A. seniculus sara and A. seniculus arctoidea share seven derived associations, and additionally A. seniculus sara has four apomorphic associations and A. seniculus arctoidea seven apomorphic associations. A. belzebul appears to have a more conserved karyotype than the red h owlers. Both red and black-and-red howlers are characterized by Y-auto some translocations; the peculiar chromosomal sex system found in the red howler taxa could be considered a further transformation of the A. belzebul sex system. The finding that apparently morphologically simi lar or even identical taxa have such extreme genomic differences has i mportant implications for speciation theory and neotropical primate co nservation. (C) 1998 Wiley-Liss, Inc.