Investigating the Genetic Basis of Plumage Variation in the Australian Magpie, Cracticus tibicen

Abstract

Many species exhibit some form of colour variation between groups or individuals, and studies of such colour variation, its genetic basis and functional importance can contribute unique insights into the evolutionary, ecological, demographic and genetic processes affecting the diversity of life. Through the examination of the genetics underlying colour traits, the relative importance of different selective and demographic processes in the evolution and maintenance of a trait can be inferred, enabling scientists to gain a better understanding of what drives evolutionary change in different organisms and environments. Such studies also assist in bridging the gaps in our knowledge about the interactions between genetics and ecology that are involved in phenotypic variation. Understanding the pathways linking genetic and regulatory changes to phenotypic change and evolutionary change through time contributes to our knowledge about how species develop and evolve. The Australian magpie (Cracticus tibicen), is a group-living and territorial passerine bird with a characteristic pied appearance of strongly contrasting patches of black and white plumage. The species has several different plumage forms, delineated by the colour and/or pattern of back feathers; these plumage forms hybridise where their distributions overlap. Distributions of plumage forms are highly discordant with patterns of phylogeographic structure found in this species, making a scenario of allopatric divergence followed by secondary recontact at hybrid zones highly unlikely.