1 March 2009 Postzygotic Genetic Incompatibility between Sympatric Color Morphs
Sarah R. Pryke, Simon C. Griffith
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Alternative genetically determined color morphs within a population or species are believed to successfully interbreed within a population. However, the occurrence of prezygotic or ecological selection in a number of polymorphic systems may lead to nonrandom mating and prevent genetic morphs from fully interbreeding. Here we show that postzygotic incompatibility significantly limits gene flow between the sympatric red and black color morphs of the Gouldian finch (Erythrura gouldiae). Using a balanced within-female experimental design, in which individuals were forced to breed in pure and mixed morph crosses, we found large inviability effects (>30%) in offspring resulting from genetically mixed genotypes. The consistent mortality effects across different stages of development (e.g., prehatching, juvenile, adulthood), unconfounded by environmentally derived parental effects or social environments, reveal an underlying genetic incompatibility between different genotypes. Furthermore, mortality in mixed morph genotypes was particularly severe (43.6%) for the heterogametic sex (daughters), which is consistent with Haldane's rule predicted for postzygotic incompatibilities between hybridizing species. This significant, but incomplete, postzygotic isolation suggests that the sympatric morphs may represent transient stages in the speciation-hybridization process.

© 2009 The Society for the Study of Evolution.
Sarah R. Pryke and Simon C. Griffith "Postzygotic Genetic Incompatibility between Sympatric Color Morphs," Evolution 63(3), 793-798, (1 March 2009). https://doi.org/10.1111/j.1558-5646.2008.00584.x
Received: 12 June 2008; Accepted: 1 November 2008; Published: 1 March 2009

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assortative mating
color polymorphism
Gouldian Finch
postzygotic incompatibility
reproductive isolation
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