Behavioral Plasticity and the Origins of Novelty: The Evolution of the Rattlesnake Rattle

Abstract

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.

Does rattling deter? The case of domestic dogs

“…Williams () proposed that rattling, which evolved from defensive tail vibrations (Allf, Durst, & Pfennig, ; Greene, ), functions not to warn but to direct threatening attention away from the snake's head. However, the likelihood of an aposematic function of rattling is supported by a good deal of indirect evidence (Greene, ).…”

“…Based on the number of envenomations and the location of the bites, which suggest that dogs are moving toward the snake when bitten, it appears that dogs may approach rather than avoid rattlesnakes they encounter. Mulholland, Olivas, and Caine (2018) found that dogs showed no evidence of fear or avoidance in the presence of rattlesnake odors, nor did they avoid approaching and eating in front of realistic rattlesnake models (R. Muñoz, unpublished data).…”

Developmental bias in horned dung beetles and its contributions to innovation, adaptation, and resilience

“…As such it constitutes a mechanism whereby initially environmentally induced traits, including the products of phenotypic accommodation, may become genetically stabilized or canalized, for instance when plastic responses to environmental conditions make visible to selection cryptic genetic variation accumulated during previous generations (Paaby & Rockman, 2014). Similarly, earlier work posited that because behavioral traits often exhibit both extreme plasticity and evolutionary lability, behavior may be more likely to evolve by genetic accommodation than other organismal features such as morphology (Allf, Durst, & Pfennig, 2016;West-Eberhard, 1986. Collectively, this body of work demonstrates the feasibility and potential significance of genetic accommodation in evolution.…”

El uso de señales aposemáticas en serpientes: contra advertencia no hay engaño

“…Este complejo mecanismo de comunicación evolucionó bajo la presión de fuerzas selectivas como una señal de defensa (Greene, 1988;Meik y Pires-daSilva, 2009;Allf et al, 2016). Sin embargo, a pesar de que el uso del cascabel es en principio un método eficiente para disuadir a los depredadores, puede representar un costo muy alto al revelar la posición exacta de la serpiente (Clark, 2004), ya que a pesar de contar con un armamento venenoso este tipo de vipérido sigue siendo presa de una gran cantidad de depredadores (Klauber, 1956;Greene, 1988).…”