DOI: 10.5061/dryad.42s0c
title: Data from: Feeding ecology is the primary driver of beak shape diversification in waterfowl

description: The diversity of beak shapes among birds is often assumed to be largely
 the result of adaptations to different feeding behaviors and diets.
 However, this assumption has only been tested for a small subset of avian
 diversity, primarily within the order Passeriformes. Moreover, given the
 role of the beak in behaviors other than feeding and given that most
 previously identified beak-feeding associations concern beak size rather
 than shape, it remains unclear how much of beak shape diversity is
 explained by feeding ecology and what functional explanations account for
 these differences in shape. I quantified the association between beak
 shape and feeding ecology for 42 species in the bird order Anseriformes
 (waterfowl) using 3D curvature of the upper beak collected from museum
 specimens and continuous dietary data compiled from the literature. I also
 tested whether leverage or stress resistance of the beak explains the
 association between beak shape and feeding ecology. Diet is strongly and
 significantly correlated with beak shape in waterfowl. An ancestral beak
 shape reconstruction and the reconstructed diet of the anseriform fossil
 Presbyornis both support filter-feeding as ancestral for most waterfowl,
 followed by multiple, significantly convergent transitions from a
 duck-like beak toward a more goose-like beak. The evolution of a more
 goose-like beak is associated with increased consumption of leaves,
 decreased consumption of invertebrates, and an increase in mechanical
 advantage of the beak. Moreover, no association was identified between
 size (measured as either beak size or body mass) and feeding ecology nor
 between size and beak shape. These results demonstrate that feeding
 ecology has acted as the primary selective force in the diversification of
 waterfowl beak shapes, including the convergent originations of geese.
 Thus, rapid and convergent adaptation of the beak to feeding is not
 limited to passerines nor is it limited to size-correlated shape changes.
 The positive evolutionary correlation between mechanical advantage and
 herbivory shows that lever mechanics can explain the functional evolution
 of the kinetic upper beak in birds. These results also suggest that
 functions of the beak other than feeding may play a minor role in
 explaining overall beak shape diversity.
description: Beak shape by
 speciesA folder containing the
 species-averaged beak semilandmark coordinates, with each species in a
 separate file.Beak shape by
 specimenA folder containing beak
 semilandmark coordinates by specimen, with each specimen in a separate
 file.Beak shape specimen
 listA
 table of accession numbers and the collection source for all specimens
 used in this study.Burleigh, Kimball,
 Braun, 2015 ML Tree, prunedThe tree used in this
 study. This is a tree from Burleigh, Kimball and Braun 2015, pruned to
 only include the species in this study.Diet composition
 fullA
 spreadsheet of diet composition for each species, including the
 composition from each separate study and the average (in bold) across
 studies for each species.Diet
 compositionA table of mean body
 mass and diet composition for each species.