Data from: Behavioral plasticity and the origins of novelty: the evolution of the rattlesnake rattle

Environmentally induced behavior (behavioral plasticity) has long been
hypothesized to promote the origins of novel morphological traits, but
this idea remains controversial. One context in which this hypothesis can
be evaluated is animal communication, where behavior and morphology are
often linked. Here, we examined the evolution of one of nature’s most
spectacular communication signals: the rattlesnake rattle. We specifically
evaluated whether rattlesnake rattling behavior—and, hence, the
rattle—originated from a simple behavior: vibrating the tail when
threatened. By reconstructing the ancestral state of defensive tail
vibration, we show that this behavior is nearly ubiquitous in the
Viperidae (the family that includes rattlesnakes) and widespread in the
Colubridae (the largest snake family, nearly all of which are
nonvenomous), suggesting a shared origin for the behavior between these
families. After measuring tail vibration in 56 species of Viperidae and
Colubridae, we show that the more closely related a species was to
rattlesnakes, the more similar it was to rattlesnakes in duration and rate
of tail vibration. Thus, the rattlesnake rattle might have evolved via
elaboration of a simple behavior. These data thereby support the
long-standing hypothesis that behavioral plasticity often precedes—and
possibly instigates—the evolution of morphological novelty.