Related Experiment Video
Updated: Jul 21, 2026

Probing the Limits of Egg Recognition Using Egg Rejection Experiments Along Phenotypic Gradients
Published on: August 22, 2018
Extreme reversed sexual dichromatism in a bird without sex role reversal
Robert Heinsohn1, Sarah Legge, John A Endler
1Centre for Resource and Environmental Studies, Australian National University, Canberra, ACT 0200 Australia. Robert.Heinsohn@anu.edu.au
Abstract:
Brilliant plumage is typical of male birds, reflecting differential enhancement of male traits when females are the limiting sex. Brighter females are thought to evolve exclusively in response to sex role reversal. The striking reversed plumage dichromatism of Eclectus roratus parrots does not fit this pattern. We quantify plumage color in this species and show that very different selection pressures are acting on males and females. Male plumage reflects a compromise between the conflicting requirements for camouflage from predators while foraging and conspicuousness during display. Females are liberated from the need for camouflage but compete for rare nest hollows.
Related Concept Videos
Mate Choice
Types of Selection
X-linked Traits
Position-effect Variegation
The Ratio of X Chromosome to Autosomes
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Complementation Tests
Organisms heterozygous for different mutations are crossed pairwise in all combinations. If present on different genes, the mutations can complement each other by providing the missing...

