Chromosomal evolution in serpentes; a comparison of G and C chromosome banding patterns of some colubrid and boid genera

G and C-chromosome banding techniques have been used to compare the structure of the karyotype in a variety of colubrid and boid snakes. The comparison of G-band patterns indicates that while some band sequences have been conserved, either as whole chromosomes or entire arms, there is also evidence of considerable rearrangement especially in the smaller chromosomes. In the colubrid Elaphe subocularis there is also evidence that there has been a relocation of the centromere on chromosome 2 without any accompanying inversion in the sequence of G-bands. Finally, G-banding has facilitated the demonstration of a simple pericentric inversion distinguishing the Z and W chromosomes in Acrantophis dumereli. This represents the first report of differentiated sex chromosomes in a boid snake. The combined banding data thus indicates that snake chromosomes are certainly not lacking in variability. The use of C-banding to detect constitutive heterochromatin has confirmed that in some boids and colubrids macrochromosomes have been derived from microchromosomes by the additions of heterochromatin.