Data from: Evolutionary covariation in geometric morphometric data: analyzing integration, modularity, and allometry in a phylogenetic context

Quantifying integration and modularity of evolutionary changes in
morphometric traits is crucial for understanding how organismal shapes
evolve. For this purpose, comparative studies are necessary, which need to
take into account the phylogenetic structure of interspecific data. This
study applies several of the standard tools of geometric morphometrics,
which mostly have been used in intraspecific studies, in the new context
of analyzing integration and modularity based on comparative data.
Morphometric methods such as principal component analysis, multivariate
regression, partial least squares and modularity tests can be applied to
phylogenetically independent contrasts of shape data. We illustrate this
approach in an analysis of cranial evolution in 160 species from all
orders of birds. Mapping the shape information onto the phylogeny
indicates that there is a significant phylogenetic signal in skull shape.
Multivariate regression of independent contrasts of shape on independent
contrasts of size reveals clear evolutionary allometry. Regardless of
whether or not a correction for allometry is used, evolutionary
integration between the face and braincase is strong, and tests reject the
hypothesis that the face and braincase are separate evolutionary modules.
These analyses can easily be applied to other taxa and can be combined
with other morphometric tools to address a wide range of questions about
evolutionary patterns and processes.