Banded Karyotypes of the 44-Chromosome Gibbons

Abstract

A comparison of the 44-chromosome gibbons (27 animals from the taxa H. agilis, H. lar, H. klossii, H. muelleri, H. moloch and H. pileatus) shows that these species have a nearly identical, if not identical, G-banding pattern. Two chromosomes, No. 8 and the marker chromosome bearing the nucleolar organizing region, show intraspecific polymorphism. There are three forms of chromosome 8 (8a, 8b, 8c). Chromosome 8a can be derived from 8b by a single pericentric inversion while to derive chromosome 8c from 8b requires at least two pericentric inversions. Apparently, the 44-chromosome gibbons are chromosomally conservative or have only recently differentiated. The presence of a polymorphism of chromosome 8 in four of the six taxa studied in wild-caught animals makes it likely that this polymorphism occurs in natural populations and was the ancestral condition for all the taxa studied. However, the possible existence of natural karyomorphs has conservation implications because animals heterozygous for different forms of chromosome 8 may have lowered fertility due to the production of unbalanced gametes. The exact implications of these chromosomal polymorphisms could be further clarified by a population level study of animals of known provenance.