Data from: Building variation in visual displays through discrete modifications of motion

Interactions between conspecifics are often composed of one or more
discrete behavioural displays. Here we evaluate a behaviour used in
aggressive interactions between conspecific males of 10 species of leaf
warblers (Phylloscopus). Using high-speed videography and methods derived
from geometric morphometrics, we find that the form of a primary visual
display differs significantly among species, but with large intraspecific
variation and much overlap in shape space. Additional interspecific
differences include a species which does not move its wings at all, two
quantitatively different displays in the behavioural repertoire, and the
loss or gain of a pale patch on the wing. We conclude that display
evolution proceeds largely by adding or subtracting discrete components
from an established repertoire, accompanied by slight modifications of the
core display.  In these ways, more complex displays evolve on the
background of the ancestral signal, thereby enabling modifications to
appear without loss of ancestral efficacy.