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The bill of evolution : trophic adaptations in anseriform birds
Abstract/OtherAbstract :
Adaptive radiation involves the rapid divergence of a single ancestral species into a group of species each occupying a different ecological niche. Differences between species are the result of trade-offs in the ability to exploit different environments to avoid competitive interactions. The many species of wildfowl and their diversity in feeding methods are believed to represent an example of adaptive radiation. Frequently used feeding methods are filtering small food items from water and terrestrial grazing. However, few if any anseriform species apply both feeding methods. I have shown that duck-species have a higher performance for filter-feeding than for grazing. Geese and swans, on the other hand, have a higher performance for grazing than for filter-feeding. Structures of the tongue and roof of the upper bill are clearly related with feeding method and the corresponding mechanisms to transport food items through the bill to the oesophagus. These adaptations for either grazing or filter-feeding are incompatible and prevent maximal performance of both feeding methods at the same time. A study on the shape of the skull revealed several adaptations to feeding method. The size of the jaw muscles is exclusively related to size of the bill and only indirectly to feeding method.
Authors :
Kurk, Carolina Deborah
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Publisher :  Evolutionary Morphology, Institute of Biology, Faculty of Science, Leiden University     Type :  Doctoral thesis     Format :  application/pdf, application/pdf    
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Subject :
Adaptive radiation, Bill morphology, Filter-feeding, Foraging trade-off, Geese, Grazing, Jaw muscles, Skull morphometrics, Swans, Wildfowl
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Languages :  en    
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