Morph-dependent resource acquisition and fitness in a polymorphic bird

James Brazill-Boast*, Simon C. Griffith, Sarah R. Pryke

*Corresponding author for this work

Research output: Contribution to journalArticle

17 Citations (Scopus)


Understanding genetic colour polymorphism has proved a major challenge, both in terms of the underlying genetic mechanisms and the evolutionarily forces maintaining such genetic variation. In this context, genetic differences in aggression or competitive-related traits may covary with the expression of alternative phenotypes, and affect the evolutionary stability and maintenance of colour polymorphisms. Genetic red and black head-colour morphs of the Gouldian finch (Erythrura gouldiae) co-occur in temporally and geographically stable frequencies in sympatric populations. Gouldian finches are obligate cavity-nesters with highly specific preferences for nest-site morphometry that directly affect reproductive success. Because intra- and interspecific competition for high quality nest-sites is prevalent, and fitness is directly related to nest-site quality, we investigated the relative access (and consequences for reproductive success) of alternative morphs to this critical limiting resource in the wild. Red males defended higher quality nest-sites, and overcame greater levels of nest-site competition against conspecifics and superior heterospecific competitors than black males. Red-headed males also produced more fledglings (especially with red-headed females) than black-headed males, independent of nest-site quality. Finally, the independent (positive) effect of nest-site quality on reproductive success was confirmed. Such competitive asymmetries are important to relative selection among coexisting morphs, and are likely to contribute to the maintenance of alternative sympatric colour-morphs in wild populations.

Original languageEnglish
Pages (from-to)1189-1198
Number of pages10
JournalEvolutionary Ecology
Issue number6
Publication statusPublished - Nov 2013

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