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The extraordinary bill dimorphism of the Huia ( Heteraclocha acutirostris ): sexual selection or intersexual competition?

TitleThe extraordinary bill dimorphism of the Huia ( Heteraclocha acutirostris ): sexual selection or intersexual competition?
Publication TypeJournal Article
Year of Publication1996
JournalNotornis
Volume43
Issue1
Pagination19-34
Type of Articlepaper
KeywordsCallaeidae, competition, Huia, sexual dimorphism
Abstract

Morphological comparison of the extinct Huia (Heteralocha acutirostris) with its closest known relatives suggests that the pronounced sexual bill dimorphism of the former evolved through selection on female, rather than male bill form. Because sexual selection acts predominantly on males, it cannot readily explain such dimorphism in a non-polyandrous species. Greater female divergence in foraging-related anatomy in a species in which males are the larger (and therefore presumably socially dominant) sex is, however, consistent with the hypothesis that sexual dimorphism can be an adaptation to reduce intersexual competition for food. Determining which sex changed most is a more rigorous means of establishing the evolutionary significance of sexually dimorphic traits than interpretation of current function.

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