Multigenerational pedigree analysis of wild individually marked black sparrowhawks suggests that dark plumage coloration is a dominant autosomal trait: Data
Nebel C, Sumasgutner P, Rodseth E, Ingle RA, Childs DZ, Curtis-Scott O, Amar A. Multigenerational pedigree analysis of wild individually marked black sparrowhawks suggests that dark plumage coloration is a dominant autosomal trait. Journal of Zoology (in press)
Abstract:
The black sparrowhawk (Accipiter melanoleucus) is a color-polymorphic sub-Saharan raptor, with adults occurring in two discrete color morphs: dark and light. It has previously been suggested that plumage colouration is determined by a one-locus two-allele system with the light allele being dominant over the dark allele. Here, we revisit the assumption with an extended dataset of 130 individuals and pedigree information from 75 individuals five generations. We test the observed offspring phenotypic ratio against the expected ratio under Hardy-Weinberg equilibrium and find significant deviations from the expected values. Contrary to the previous assumption, our data indicate that the dark allele is in fact dominant over the light allele. Similarily, the multigenerational pedigrees obtained are incompatible with a one-locus two-allele system where the light allele is dominant but are consistent with a scenario where the dark allele is dominant instead. However, without knowledge of the underlying molecular basis of plumage polymorphisms, uncertainty remains, and the intra-morph variation observed suggests that modifier genes or environmental factors may also be involved. Our study provides a foundation for future research on the adaptive function of colour polymorphism in the species but also highlights the need for caution when drawing conclusions about the mode of inheritance in wild animal populations in the absence of genetic data, especially when one variant is much rarer than the other.