CHROMOSOMAL POLYMORPHISM COMMON TO SEVERAL SPECIES OF JUNCO (AVES)

Abstract

Karyotypes were obtained from primary kidney cultures of nearly 250 individuals belonging to six nominate species of the avian genus Junco. Chromosome 2 was found to be dimorphic in four of the six species and chromosome 5 was dimorphic in five of the six species. The dimorphism appears to be due to the presence of a pericentric inversion in each of these autosomes. It is hypothesized that chromosomes 2 and 5 are ancestral and gave rise to chromosomes 2sm and 5m respectively. The sample of the slate-colored junco, Junco hyemalis, the largest studied, conforms to the Hardy-Weinberg equilibrium and suggests that a random sample was drawn from a randomly mating population.