CHROMOSOMAL UNIFORMITY IN THE AVIAN SUBCLASS CARINATAE.

Abstract

1. A method for making two-dimensional measurements of colchicinized metaphase chromosomes was applied to six avian species and one interfamilial hybrid of the subclass Carinatae: the canary (Serinus canarius, 2n=80±), the parakeet (Melopsittacus undulatus, 2n=58±), the pigeon (Columba livia domestica, 2n= 80±), the turkey-pheasant hybrid (♂ Meleagris gallopavo × ♀ Phasianus colchicus, 2n=80±), the Japanese quail (Coturnix coturnix japonica, 2n=78 ±), the jungle fowl of Java (Gallus gallus bankivo, 2n=78 ±), and the duck (Anas platyrhyncha domestica, 2n=80 ±). 2. In these species representing five different orders of diverse geographic origin, the total chromosome area varied only from 62.42 μ2 in the turkey-pheasant hybrid to 67.95 μ2 in the parakeet. 3. The absolute size of the Z-chromosome was equally uniform, ranging only from 2.3 μ2 in the pigeon and duck to 3.0 μ2 in the canary. A W-chromosome two-thirds as large as the Z was noted in the female canary and pigeon; thus the sex chromosome constitution of the heterogametic sex in all avian species is probably ZW, not ZO. 4. Class Aves, subclass Carinatae, constitutes an independently uniform class with regard to the total chromosome area and the absolute size of the Z-chromosome.