title: Chromosome banding pattern conservatism in birds and nonhomology of chromosome banding patterns between birds, turtles, snakes and amphibians.
abstract: The G-banded karyotypes of 4 species of birds representing the orders Galliformes, Columbiformes and Musophagiformes were compared. Banding pattern homology between orders was limited t 5o 5 major chromosome arms and the Z chromosome. Even in these major chromosome arms pericentric and paracentric inversions produced alteration of the banding pattern sequences. Addition of constitutive heterochromatin was responsible for changes in banding patterns in the Z chromosome. The chromosome banding patterns of an emydid turtle, Terrepene carolina, 5 species of boid snakes of the genera Liasis, Acrantophis, and Sanzinia and the African clawed-frog. Xenopus muelleri, were also compared to the bird chromosome banding patterns. No homology was observed between any of these major groups: bird, snake, turtle, amphibian. However, intergroup homology was apparent. - The data obtained do not support reports of broad interordinal direct homology of the macrochromosomes of birds and refutes the idea of a primitive bird karyotype with 3 pairs of "Agroup' chromosomes and 3 pairs of "B group' chromosomes. - The major mechanisms responsible for chromosome evolution in birds appear to be centric and tandem fusions, paracentric and pericentric inversions, and addition or deletion of heterochromatin.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds; D002645:Chickens; D002875:Chromosomes / Q000032:analysis*; D007621:Karyotyping; D010802:Phylogeny; D012911:Snakes; D013194:Staining and Labeling; D014357:Trypsin; D014426:Turtles; D014981:Xenopus
chemical_list: D014357:Trypsin