Hybrid Phenotypes in Male Figbirds Sphecotheres viridis in Queensland

Abstract

Two distinctive forms of Sphecotheres viridis hybridize in lower northeastern Queensland:the yellow-breasted flaviventris and grey-breasted vieilloti. Hybridization was quantitatively assessed in 1976-80 by collecting specimens and counting phenotypes of wild male buds. Two kinds of gradation in phenotype were discovered: a series in which the throat and breast varied from yellow through green to dark grey; and a series in which the throat and breast were white or various shades of grey. Most differences in coloration between flaviventris and vieilloti may be explained in terms of two gene loci, one locus controlling deposition of yellow carotenoid and the other controlling melanin in the feathers on the throat and breast; hybrids with white on the throat and breast apparently have a combination of recessive alleles. Hybrids predominate in the region of Townsville and the hybrid zone is very broad. Contact appears to be secondary and may have existed for 9,500 to 14,000 years. A subspecific relationship between flaviventris and vieilloti is confirmed.